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3370 lines
118 KiB
3370 lines
118 KiB
# engine/base.py
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# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: https://www.opensource.org/licenses/mit-license.php
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from __future__ import with_statement
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import contextlib
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import sys
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from .interfaces import Connectable
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from .interfaces import ExceptionContext
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from .util import _distill_params
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from .util import _distill_params_20
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from .util import TransactionalContext
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from .. import exc
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from .. import inspection
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from .. import log
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from .. import util
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from ..sql import compiler
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from ..sql import util as sql_util
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"""Defines :class:`_engine.Connection` and :class:`_engine.Engine`.
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"""
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_EMPTY_EXECUTION_OPTS = util.immutabledict()
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class Connection(Connectable):
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"""Provides high-level functionality for a wrapped DB-API connection.
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**This is the SQLAlchemy 1.x.x version** of the :class:`_engine.Connection`
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class. For the :term:`2.0 style` version, which features some API
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differences, see :class:`_future.Connection`.
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The :class:`_engine.Connection` object is procured by calling
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the :meth:`_engine.Engine.connect` method of the :class:`_engine.Engine`
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object, and provides services for execution of SQL statements as well
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as transaction control.
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The Connection object is **not** thread-safe. While a Connection can be
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shared among threads using properly synchronized access, it is still
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possible that the underlying DBAPI connection may not support shared
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access between threads. Check the DBAPI documentation for details.
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The Connection object represents a single DBAPI connection checked out
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from the connection pool. In this state, the connection pool has no affect
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upon the connection, including its expiration or timeout state. For the
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connection pool to properly manage connections, connections should be
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returned to the connection pool (i.e. ``connection.close()``) whenever the
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connection is not in use.
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.. index::
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single: thread safety; Connection
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"""
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_is_future = False
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_sqla_logger_namespace = "sqlalchemy.engine.Connection"
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# used by sqlalchemy.engine.util.TransactionalContext
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_trans_context_manager = None
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def __init__(
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self,
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engine,
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connection=None,
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close_with_result=False,
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_branch_from=None,
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_execution_options=None,
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_dispatch=None,
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_has_events=None,
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_allow_revalidate=True,
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):
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"""Construct a new Connection."""
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self.engine = engine
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self.dialect = engine.dialect
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self.__branch_from = _branch_from
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if _branch_from:
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# branching is always "from" the root connection
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assert _branch_from.__branch_from is None
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self._dbapi_connection = connection
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self._execution_options = _execution_options
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self._echo = _branch_from._echo
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self.should_close_with_result = False
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self.dispatch = _dispatch
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self._has_events = _branch_from._has_events
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else:
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self._dbapi_connection = (
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connection
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if connection is not None
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else engine.raw_connection()
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)
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self._transaction = self._nested_transaction = None
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self.__savepoint_seq = 0
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self.__in_begin = False
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self.should_close_with_result = close_with_result
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self.__can_reconnect = _allow_revalidate
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self._echo = self.engine._should_log_info()
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if _has_events is None:
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# if _has_events is sent explicitly as False,
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# then don't join the dispatch of the engine; we don't
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# want to handle any of the engine's events in that case.
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self.dispatch = self.dispatch._join(engine.dispatch)
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self._has_events = _has_events or (
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_has_events is None and engine._has_events
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)
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assert not _execution_options
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self._execution_options = engine._execution_options
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if self._has_events or self.engine._has_events:
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self.dispatch.engine_connect(self, _branch_from is not None)
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@util.memoized_property
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def _message_formatter(self):
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if "logging_token" in self._execution_options:
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token = self._execution_options["logging_token"]
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return lambda msg: "[%s] %s" % (token, msg)
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else:
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return None
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def _log_info(self, message, *arg, **kw):
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fmt = self._message_formatter
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if fmt:
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message = fmt(message)
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if util.py38:
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kw["stacklevel"] = 2
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self.engine.logger.info(message, *arg, **kw)
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def _log_debug(self, message, *arg, **kw):
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fmt = self._message_formatter
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if fmt:
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message = fmt(message)
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if util.py38:
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kw["stacklevel"] = 2
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self.engine.logger.debug(message, *arg, **kw)
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@property
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def _schema_translate_map(self):
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return self._execution_options.get("schema_translate_map", None)
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def schema_for_object(self, obj):
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"""Return the schema name for the given schema item taking into
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account current schema translate map.
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"""
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name = obj.schema
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schema_translate_map = self._execution_options.get(
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"schema_translate_map", None
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)
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if (
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schema_translate_map
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and name in schema_translate_map
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and obj._use_schema_map
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):
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return schema_translate_map[name]
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else:
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return name
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def _branch(self):
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"""Return a new Connection which references this Connection's
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engine and connection; but does not have close_with_result enabled,
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and also whose close() method does nothing.
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.. deprecated:: 1.4 the "branching" concept will be removed in
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SQLAlchemy 2.0 as well as the "Connection.connect()" method which
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is the only consumer for this.
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The Core uses this very sparingly, only in the case of
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custom SQL default functions that are to be INSERTed as the
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primary key of a row where we need to get the value back, so we have
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to invoke it distinctly - this is a very uncommon case.
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Userland code accesses _branch() when the connect()
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method is called. The branched connection
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acts as much as possible like the parent, except that it stays
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connected when a close() event occurs.
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"""
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return self.engine._connection_cls(
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self.engine,
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self._dbapi_connection,
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_branch_from=self.__branch_from if self.__branch_from else self,
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_execution_options=self._execution_options,
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_has_events=self._has_events,
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_dispatch=self.dispatch,
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)
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def _generate_for_options(self):
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"""define connection method chaining behavior for execution_options"""
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if self._is_future:
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return self
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else:
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c = self.__class__.__new__(self.__class__)
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c.__dict__ = self.__dict__.copy()
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return c
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def __enter__(self):
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return self
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def __exit__(self, type_, value, traceback):
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self.close()
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def execution_options(self, **opt):
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r""" Set non-SQL options for the connection which take effect
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during execution.
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For a "future" style connection, this method returns this same
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:class:`_future.Connection` object with the new options added.
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For a legacy connection, this method returns a copy of this
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:class:`_engine.Connection` which references the same underlying DBAPI
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connection, but also defines the given execution options which will
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take effect for a call to
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:meth:`execute`. As the new :class:`_engine.Connection` references the
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same underlying resource, it's usually a good idea to ensure that
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the copies will be discarded immediately, which is implicit if used
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as in::
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result = connection.execution_options(stream_results=True).\
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execute(stmt)
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Note that any key/value can be passed to
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:meth:`_engine.Connection.execution_options`,
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and it will be stored in the
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``_execution_options`` dictionary of the :class:`_engine.Connection`.
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It
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is suitable for usage by end-user schemes to communicate with
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event listeners, for example.
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The keywords that are currently recognized by SQLAlchemy itself
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include all those listed under :meth:`.Executable.execution_options`,
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as well as others that are specific to :class:`_engine.Connection`.
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:param autocommit: Available on: Connection, statement.
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When True, a COMMIT will be invoked after execution
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when executed in 'autocommit' mode, i.e. when an explicit
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transaction is not begun on the connection. Note that this
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is **library level, not DBAPI level autocommit**. The DBAPI
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connection will remain in a real transaction unless the
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"AUTOCOMMIT" isolation level is used.
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.. deprecated:: 1.4 The "autocommit" execution option is deprecated
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and will be removed in SQLAlchemy 2.0. See
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:ref:`migration_20_autocommit` for discussion.
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:param compiled_cache: Available on: Connection.
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A dictionary where :class:`.Compiled` objects
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will be cached when the :class:`_engine.Connection`
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compiles a clause
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expression into a :class:`.Compiled` object. This dictionary will
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supersede the statement cache that may be configured on the
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:class:`_engine.Engine` itself. If set to None, caching
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is disabled, even if the engine has a configured cache size.
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Note that the ORM makes use of its own "compiled" caches for
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some operations, including flush operations. The caching
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used by the ORM internally supersedes a cache dictionary
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specified here.
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:param logging_token: Available on: :class:`_engine.Connection`,
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:class:`_engine.Engine`.
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Adds the specified string token surrounded by brackets in log
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messages logged by the connection, i.e. the logging that's enabled
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either via the :paramref:`_sa.create_engine.echo` flag or via the
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``logging.getLogger("sqlalchemy.engine")`` logger. This allows a
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per-connection or per-sub-engine token to be available which is
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useful for debugging concurrent connection scenarios.
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.. versionadded:: 1.4.0b2
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.. seealso::
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:ref:`dbengine_logging_tokens` - usage example
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:paramref:`_sa.create_engine.logging_name` - adds a name to the
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name used by the Python logger object itself.
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:param isolation_level: Available on: :class:`_engine.Connection`.
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Set the transaction isolation level for the lifespan of this
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:class:`_engine.Connection` object.
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Valid values include those string
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values accepted by the :paramref:`_sa.create_engine.isolation_level`
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parameter passed to :func:`_sa.create_engine`. These levels are
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semi-database specific; see individual dialect documentation for
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valid levels.
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The isolation level option applies the isolation level by emitting
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statements on the DBAPI connection, and **necessarily affects the
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original Connection object overall**, not just the copy that is
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returned by the call to :meth:`_engine.Connection.execution_options`
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method. The isolation level will remain at the given setting until
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the DBAPI connection itself is returned to the connection pool, i.e.
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the :meth:`_engine.Connection.close` method on the original
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:class:`_engine.Connection` is called,
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where an event handler will emit
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additional statements on the DBAPI connection in order to revert the
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isolation level change.
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.. warning:: The ``isolation_level`` execution option should
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**not** be used when a transaction is already established, that
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is, the :meth:`_engine.Connection.begin`
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method or similar has been
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called. A database cannot change the isolation level on a
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transaction in progress, and different DBAPIs and/or
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SQLAlchemy dialects may implicitly roll back or commit
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the transaction, or not affect the connection at all.
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.. note:: The ``isolation_level`` execution option is implicitly
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reset if the :class:`_engine.Connection` is invalidated, e.g. via
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the :meth:`_engine.Connection.invalidate` method, or if a
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disconnection error occurs. The new connection produced after
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the invalidation will not have the isolation level re-applied
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to it automatically.
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.. seealso::
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:paramref:`_sa.create_engine.isolation_level`
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- set per :class:`_engine.Engine` isolation level
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:meth:`_engine.Connection.get_isolation_level`
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- view current level
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:ref:`SQLite Transaction Isolation <sqlite_isolation_level>`
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:ref:`PostgreSQL Transaction Isolation <postgresql_isolation_level>`
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:ref:`MySQL Transaction Isolation <mysql_isolation_level>`
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:ref:`SQL Server Transaction Isolation <mssql_isolation_level>`
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:ref:`session_transaction_isolation` - for the ORM
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:param no_parameters: When ``True``, if the final parameter
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list or dictionary is totally empty, will invoke the
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statement on the cursor as ``cursor.execute(statement)``,
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not passing the parameter collection at all.
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Some DBAPIs such as psycopg2 and mysql-python consider
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percent signs as significant only when parameters are
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present; this option allows code to generate SQL
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containing percent signs (and possibly other characters)
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that is neutral regarding whether it's executed by the DBAPI
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or piped into a script that's later invoked by
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command line tools.
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:param stream_results: Available on: Connection, statement.
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Indicate to the dialect that results should be
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"streamed" and not pre-buffered, if possible. This is a limitation
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of many DBAPIs. The flag is currently understood within a subset
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of dialects within the PostgreSQL and MySQL categories, and
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may be supported by other third party dialects as well.
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.. seealso::
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:ref:`engine_stream_results`
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:param schema_translate_map: Available on: Connection, Engine.
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A dictionary mapping schema names to schema names, that will be
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applied to the :paramref:`_schema.Table.schema` element of each
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:class:`_schema.Table`
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encountered when SQL or DDL expression elements
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are compiled into strings; the resulting schema name will be
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converted based on presence in the map of the original name.
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.. versionadded:: 1.1
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.. seealso::
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:ref:`schema_translating`
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.. seealso::
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:meth:`_engine.Engine.execution_options`
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:meth:`.Executable.execution_options`
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:meth:`_engine.Connection.get_execution_options`
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""" # noqa
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c = self._generate_for_options()
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c._execution_options = c._execution_options.union(opt)
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if self._has_events or self.engine._has_events:
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self.dispatch.set_connection_execution_options(c, opt)
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self.dialect.set_connection_execution_options(c, opt)
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return c
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def get_execution_options(self):
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"""Get the non-SQL options which will take effect during execution.
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.. versionadded:: 1.3
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.. seealso::
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:meth:`_engine.Connection.execution_options`
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"""
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return self._execution_options
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@property
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def closed(self):
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"""Return True if this connection is closed."""
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# note this is independent for a "branched" connection vs.
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# the base
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return self._dbapi_connection is None and not self.__can_reconnect
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@property
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def invalidated(self):
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"""Return True if this connection was invalidated."""
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# prior to 1.4, "invalid" was stored as a state independent of
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# "closed", meaning an invalidated connection could be "closed",
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# the _dbapi_connection would be None and closed=True, yet the
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# "invalid" flag would stay True. This meant that there were
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# three separate states (open/valid, closed/valid, closed/invalid)
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# when there is really no reason for that; a connection that's
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# "closed" does not need to be "invalid". So the state is now
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# represented by the two facts alone.
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if self.__branch_from:
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return self.__branch_from.invalidated
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return self._dbapi_connection is None and not self.closed
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|
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@property
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def connection(self):
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"""The underlying DB-API connection managed by this Connection.
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This is a SQLAlchemy connection-pool proxied connection
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which then has the attribute
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:attr:`_pool._ConnectionFairy.dbapi_connection` that refers to the
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actual driver connection.
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|
.. seealso::
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|
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:ref:`dbapi_connections`
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"""
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|
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if self._dbapi_connection is None:
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try:
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return self._revalidate_connection()
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except (exc.PendingRollbackError, exc.ResourceClosedError):
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raise
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except BaseException as e:
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self._handle_dbapi_exception(e, None, None, None, None)
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else:
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return self._dbapi_connection
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|
|
def get_isolation_level(self):
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"""Return the current isolation level assigned to this
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:class:`_engine.Connection`.
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This will typically be the default isolation level as determined
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by the dialect, unless if the
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:paramref:`.Connection.execution_options.isolation_level`
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feature has been used to alter the isolation level on a
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per-:class:`_engine.Connection` basis.
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This attribute will typically perform a live SQL operation in order
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to procure the current isolation level, so the value returned is the
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actual level on the underlying DBAPI connection regardless of how
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this state was set. Compare to the
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:attr:`_engine.Connection.default_isolation_level` accessor
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which returns the dialect-level setting without performing a SQL
|
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query.
|
|
|
|
.. versionadded:: 0.9.9
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|
.. seealso::
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|
:attr:`_engine.Connection.default_isolation_level`
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- view default level
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:paramref:`_sa.create_engine.isolation_level`
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- set per :class:`_engine.Engine` isolation level
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:paramref:`.Connection.execution_options.isolation_level`
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- set per :class:`_engine.Connection` isolation level
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"""
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try:
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return self.dialect.get_isolation_level(self.connection)
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except BaseException as e:
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self._handle_dbapi_exception(e, None, None, None, None)
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|
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@property
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def default_isolation_level(self):
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"""The default isolation level assigned to this
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:class:`_engine.Connection`.
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This is the isolation level setting that the
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:class:`_engine.Connection`
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has when first procured via the :meth:`_engine.Engine.connect` method.
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This level stays in place until the
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:paramref:`.Connection.execution_options.isolation_level` is used
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to change the setting on a per-:class:`_engine.Connection` basis.
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|
Unlike :meth:`_engine.Connection.get_isolation_level`,
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this attribute is set
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ahead of time from the first connection procured by the dialect,
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so SQL query is not invoked when this accessor is called.
|
|
|
|
.. versionadded:: 0.9.9
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|
|
.. seealso::
|
|
|
|
:meth:`_engine.Connection.get_isolation_level`
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|
- view current level
|
|
|
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:paramref:`_sa.create_engine.isolation_level`
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|
- set per :class:`_engine.Engine` isolation level
|
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|
|
:paramref:`.Connection.execution_options.isolation_level`
|
|
- set per :class:`_engine.Connection` isolation level
|
|
|
|
"""
|
|
return self.dialect.default_isolation_level
|
|
|
|
def _invalid_transaction(self):
|
|
if self.invalidated:
|
|
raise exc.PendingRollbackError(
|
|
"Can't reconnect until invalid %stransaction is rolled "
|
|
"back."
|
|
% (
|
|
"savepoint "
|
|
if self._nested_transaction is not None
|
|
else ""
|
|
),
|
|
code="8s2b",
|
|
)
|
|
else:
|
|
assert not self._is_future
|
|
raise exc.PendingRollbackError(
|
|
"This connection is on an inactive %stransaction. "
|
|
"Please rollback() fully before proceeding."
|
|
% (
|
|
"savepoint "
|
|
if self._nested_transaction is not None
|
|
else ""
|
|
),
|
|
code="8s2a",
|
|
)
|
|
|
|
def _revalidate_connection(self):
|
|
if self.__branch_from:
|
|
return self.__branch_from._revalidate_connection()
|
|
if self.__can_reconnect and self.invalidated:
|
|
if self._transaction is not None:
|
|
self._invalid_transaction()
|
|
self._dbapi_connection = self.engine.raw_connection(
|
|
_connection=self
|
|
)
|
|
return self._dbapi_connection
|
|
raise exc.ResourceClosedError("This Connection is closed")
|
|
|
|
@property
|
|
def _still_open_and_dbapi_connection_is_valid(self):
|
|
return self._dbapi_connection is not None and getattr(
|
|
self._dbapi_connection, "is_valid", False
|
|
)
|
|
|
|
@property
|
|
def info(self):
|
|
"""Info dictionary associated with the underlying DBAPI connection
|
|
referred to by this :class:`_engine.Connection`, allowing user-defined
|
|
data to be associated with the connection.
|
|
|
|
The data here will follow along with the DBAPI connection including
|
|
after it is returned to the connection pool and used again
|
|
in subsequent instances of :class:`_engine.Connection`.
|
|
|
|
"""
|
|
|
|
return self.connection.info
|
|
|
|
@util.deprecated_20(":meth:`.Connection.connect`")
|
|
def connect(self, close_with_result=False):
|
|
"""Returns a branched version of this :class:`_engine.Connection`.
|
|
|
|
The :meth:`_engine.Connection.close` method on the returned
|
|
:class:`_engine.Connection` can be called and this
|
|
:class:`_engine.Connection` will remain open.
|
|
|
|
This method provides usage symmetry with
|
|
:meth:`_engine.Engine.connect`, including for usage
|
|
with context managers.
|
|
|
|
"""
|
|
|
|
return self._branch()
|
|
|
|
def invalidate(self, exception=None):
|
|
"""Invalidate the underlying DBAPI connection associated with
|
|
this :class:`_engine.Connection`.
|
|
|
|
An attempt will be made to close the underlying DBAPI connection
|
|
immediately; however if this operation fails, the error is logged
|
|
but not raised. The connection is then discarded whether or not
|
|
close() succeeded.
|
|
|
|
Upon the next use (where "use" typically means using the
|
|
:meth:`_engine.Connection.execute` method or similar),
|
|
this :class:`_engine.Connection` will attempt to
|
|
procure a new DBAPI connection using the services of the
|
|
:class:`_pool.Pool` as a source of connectivity (e.g.
|
|
a "reconnection").
|
|
|
|
If a transaction was in progress (e.g. the
|
|
:meth:`_engine.Connection.begin` method has been called) when
|
|
:meth:`_engine.Connection.invalidate` method is called, at the DBAPI
|
|
level all state associated with this transaction is lost, as
|
|
the DBAPI connection is closed. The :class:`_engine.Connection`
|
|
will not allow a reconnection to proceed until the
|
|
:class:`.Transaction` object is ended, by calling the
|
|
:meth:`.Transaction.rollback` method; until that point, any attempt at
|
|
continuing to use the :class:`_engine.Connection` will raise an
|
|
:class:`~sqlalchemy.exc.InvalidRequestError`.
|
|
This is to prevent applications from accidentally
|
|
continuing an ongoing transactional operations despite the
|
|
fact that the transaction has been lost due to an
|
|
invalidation.
|
|
|
|
The :meth:`_engine.Connection.invalidate` method,
|
|
just like auto-invalidation,
|
|
will at the connection pool level invoke the
|
|
:meth:`_events.PoolEvents.invalidate` event.
|
|
|
|
:param exception: an optional ``Exception`` instance that's the
|
|
reason for the invalidation. is passed along to event handlers
|
|
and logging functions.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`pool_connection_invalidation`
|
|
|
|
"""
|
|
|
|
if self.__branch_from:
|
|
return self.__branch_from.invalidate(exception=exception)
|
|
|
|
if self.invalidated:
|
|
return
|
|
|
|
if self.closed:
|
|
raise exc.ResourceClosedError("This Connection is closed")
|
|
|
|
if self._still_open_and_dbapi_connection_is_valid:
|
|
self._dbapi_connection.invalidate(exception)
|
|
self._dbapi_connection = None
|
|
|
|
def detach(self):
|
|
"""Detach the underlying DB-API connection from its connection pool.
|
|
|
|
E.g.::
|
|
|
|
with engine.connect() as conn:
|
|
conn.detach()
|
|
conn.execute(text("SET search_path TO schema1, schema2"))
|
|
|
|
# work with connection
|
|
|
|
# connection is fully closed (since we used "with:", can
|
|
# also call .close())
|
|
|
|
This :class:`_engine.Connection` instance will remain usable.
|
|
When closed
|
|
(or exited from a context manager context as above),
|
|
the DB-API connection will be literally closed and not
|
|
returned to its originating pool.
|
|
|
|
This method can be used to insulate the rest of an application
|
|
from a modified state on a connection (such as a transaction
|
|
isolation level or similar).
|
|
|
|
"""
|
|
|
|
self._dbapi_connection.detach()
|
|
|
|
def _autobegin(self):
|
|
self.begin()
|
|
|
|
def begin(self):
|
|
"""Begin a transaction and return a transaction handle.
|
|
|
|
The returned object is an instance of :class:`.Transaction`.
|
|
This object represents the "scope" of the transaction,
|
|
which completes when either the :meth:`.Transaction.rollback`
|
|
or :meth:`.Transaction.commit` method is called.
|
|
|
|
.. tip::
|
|
|
|
The :meth:`_engine.Connection.begin` method is invoked when using
|
|
the :meth:`_engine.Engine.begin` context manager method as well.
|
|
All documentation that refers to behaviors specific to the
|
|
:meth:`_engine.Connection.begin` method also apply to use of the
|
|
:meth:`_engine.Engine.begin` method.
|
|
|
|
Legacy use: nested calls to :meth:`.begin` on the same
|
|
:class:`_engine.Connection` will return new :class:`.Transaction`
|
|
objects that represent an emulated transaction within the scope of the
|
|
enclosing transaction, that is::
|
|
|
|
trans = conn.begin() # outermost transaction
|
|
trans2 = conn.begin() # "nested"
|
|
trans2.commit() # does nothing
|
|
trans.commit() # actually commits
|
|
|
|
Calls to :meth:`.Transaction.commit` only have an effect
|
|
when invoked via the outermost :class:`.Transaction` object, though the
|
|
:meth:`.Transaction.rollback` method of any of the
|
|
:class:`.Transaction` objects will roll back the
|
|
transaction.
|
|
|
|
.. tip::
|
|
|
|
The above "nesting" behavior is a legacy behavior specific to
|
|
:term:`1.x style` use and will be removed in SQLAlchemy 2.0. For
|
|
notes on :term:`2.0 style` use, see
|
|
:meth:`_future.Connection.begin`.
|
|
|
|
|
|
.. seealso::
|
|
|
|
:meth:`_engine.Connection.begin_nested` - use a SAVEPOINT
|
|
|
|
:meth:`_engine.Connection.begin_twophase` -
|
|
use a two phase /XID transaction
|
|
|
|
:meth:`_engine.Engine.begin` - context manager available from
|
|
:class:`_engine.Engine`
|
|
|
|
"""
|
|
if self._is_future:
|
|
assert not self.__branch_from
|
|
elif self.__branch_from:
|
|
return self.__branch_from.begin()
|
|
|
|
if self.__in_begin:
|
|
# for dialects that emit SQL within the process of
|
|
# dialect.do_begin() or dialect.do_begin_twophase(), this
|
|
# flag prevents "autobegin" from being emitted within that
|
|
# process, while allowing self._transaction to remain at None
|
|
# until it's complete.
|
|
return
|
|
elif self._transaction is None:
|
|
self._transaction = RootTransaction(self)
|
|
return self._transaction
|
|
else:
|
|
if self._is_future:
|
|
raise exc.InvalidRequestError(
|
|
"This connection has already initialized a SQLAlchemy "
|
|
"Transaction() object via begin() or autobegin; can't "
|
|
"call begin() here unless rollback() or commit() "
|
|
"is called first."
|
|
)
|
|
else:
|
|
return MarkerTransaction(self)
|
|
|
|
def begin_nested(self):
|
|
"""Begin a nested transaction (i.e. SAVEPOINT) and return a
|
|
transaction handle, assuming an outer transaction is already
|
|
established.
|
|
|
|
Nested transactions require SAVEPOINT support in the
|
|
underlying database. Any transaction in the hierarchy may
|
|
``commit`` and ``rollback``, however the outermost transaction
|
|
still controls the overall ``commit`` or ``rollback`` of the
|
|
transaction of a whole.
|
|
|
|
The legacy form of :meth:`_engine.Connection.begin_nested` method has
|
|
alternate behaviors based on whether or not the
|
|
:meth:`_engine.Connection.begin` method was called previously. If
|
|
:meth:`_engine.Connection.begin` was not called, then this method will
|
|
behave the same as the :meth:`_engine.Connection.begin` method and
|
|
return a :class:`.RootTransaction` object that begins and commits a
|
|
real transaction - **no savepoint is invoked**. If
|
|
:meth:`_engine.Connection.begin` **has** been called, and a
|
|
:class:`.RootTransaction` is already established, then this method
|
|
returns an instance of :class:`.NestedTransaction` which will invoke
|
|
and manage the scope of a SAVEPOINT.
|
|
|
|
.. tip::
|
|
|
|
The above mentioned behavior of
|
|
:meth:`_engine.Connection.begin_nested` is a legacy behavior
|
|
specific to :term:`1.x style` use. In :term:`2.0 style` use, the
|
|
:meth:`_future.Connection.begin_nested` method instead autobegins
|
|
the outer transaction that can be committed using
|
|
"commit-as-you-go" style; see
|
|
:meth:`_future.Connection.begin_nested` for migration details.
|
|
|
|
.. versionchanged:: 1.4.13 The behavior of
|
|
:meth:`_engine.Connection.begin_nested`
|
|
as returning a :class:`.RootTransaction` if
|
|
:meth:`_engine.Connection.begin` were not called has been restored
|
|
as was the case in 1.3.x versions; in previous 1.4.x versions, an
|
|
outer transaction would be "autobegun" but would not be committed.
|
|
|
|
|
|
.. seealso::
|
|
|
|
:meth:`_engine.Connection.begin`
|
|
|
|
:meth:`_engine.Connection.begin_twophase`
|
|
|
|
"""
|
|
if self._is_future:
|
|
assert not self.__branch_from
|
|
elif self.__branch_from:
|
|
return self.__branch_from.begin_nested()
|
|
|
|
if self._transaction is None:
|
|
if not self._is_future:
|
|
util.warn_deprecated_20(
|
|
"Calling Connection.begin_nested() in 2.0 style use will "
|
|
"return a NestedTransaction (SAVEPOINT) in all cases, "
|
|
"that will not commit the outer transaction. For code "
|
|
"that is cross-compatible between 1.x and 2.0 style use, "
|
|
"ensure Connection.begin() is called before calling "
|
|
"Connection.begin_nested()."
|
|
)
|
|
return self.begin()
|
|
else:
|
|
self._autobegin()
|
|
|
|
return NestedTransaction(self)
|
|
|
|
def begin_twophase(self, xid=None):
|
|
"""Begin a two-phase or XA transaction and return a transaction
|
|
handle.
|
|
|
|
The returned object is an instance of :class:`.TwoPhaseTransaction`,
|
|
which in addition to the methods provided by
|
|
:class:`.Transaction`, also provides a
|
|
:meth:`~.TwoPhaseTransaction.prepare` method.
|
|
|
|
:param xid: the two phase transaction id. If not supplied, a
|
|
random id will be generated.
|
|
|
|
.. seealso::
|
|
|
|
:meth:`_engine.Connection.begin`
|
|
|
|
:meth:`_engine.Connection.begin_twophase`
|
|
|
|
"""
|
|
|
|
if self.__branch_from:
|
|
return self.__branch_from.begin_twophase(xid=xid)
|
|
|
|
if self._transaction is not None:
|
|
raise exc.InvalidRequestError(
|
|
"Cannot start a two phase transaction when a transaction "
|
|
"is already in progress."
|
|
)
|
|
if xid is None:
|
|
xid = self.engine.dialect.create_xid()
|
|
return TwoPhaseTransaction(self, xid)
|
|
|
|
def recover_twophase(self):
|
|
return self.engine.dialect.do_recover_twophase(self)
|
|
|
|
def rollback_prepared(self, xid, recover=False):
|
|
self.engine.dialect.do_rollback_twophase(self, xid, recover=recover)
|
|
|
|
def commit_prepared(self, xid, recover=False):
|
|
self.engine.dialect.do_commit_twophase(self, xid, recover=recover)
|
|
|
|
def in_transaction(self):
|
|
"""Return True if a transaction is in progress."""
|
|
if self.__branch_from is not None:
|
|
return self.__branch_from.in_transaction()
|
|
|
|
return self._transaction is not None and self._transaction.is_active
|
|
|
|
def in_nested_transaction(self):
|
|
"""Return True if a transaction is in progress."""
|
|
if self.__branch_from is not None:
|
|
return self.__branch_from.in_nested_transaction()
|
|
|
|
return (
|
|
self._nested_transaction is not None
|
|
and self._nested_transaction.is_active
|
|
)
|
|
|
|
def _is_autocommit_isolation(self):
|
|
opt_iso = self._execution_options.get("isolation_level", None)
|
|
return bool(
|
|
opt_iso == "AUTOCOMMIT"
|
|
or (
|
|
opt_iso is None
|
|
and getattr(self.engine.dialect, "isolation_level", None)
|
|
== "AUTOCOMMIT"
|
|
)
|
|
)
|
|
|
|
def get_transaction(self):
|
|
"""Return the current root transaction in progress, if any.
|
|
|
|
.. versionadded:: 1.4
|
|
|
|
"""
|
|
|
|
if self.__branch_from is not None:
|
|
return self.__branch_from.get_transaction()
|
|
|
|
return self._transaction
|
|
|
|
def get_nested_transaction(self):
|
|
"""Return the current nested transaction in progress, if any.
|
|
|
|
.. versionadded:: 1.4
|
|
|
|
"""
|
|
if self.__branch_from is not None:
|
|
|
|
return self.__branch_from.get_nested_transaction()
|
|
|
|
return self._nested_transaction
|
|
|
|
def _begin_impl(self, transaction):
|
|
assert not self.__branch_from
|
|
|
|
if self._echo:
|
|
if self._is_autocommit_isolation():
|
|
self._log_info(
|
|
"BEGIN (implicit; DBAPI should not BEGIN due to "
|
|
"autocommit mode)"
|
|
)
|
|
else:
|
|
self._log_info("BEGIN (implicit)")
|
|
|
|
self.__in_begin = True
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.begin(self)
|
|
|
|
try:
|
|
self.engine.dialect.do_begin(self.connection)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(e, None, None, None, None)
|
|
finally:
|
|
self.__in_begin = False
|
|
|
|
def _rollback_impl(self):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.rollback(self)
|
|
|
|
if self._still_open_and_dbapi_connection_is_valid:
|
|
if self._echo:
|
|
if self._is_autocommit_isolation():
|
|
self._log_info(
|
|
"ROLLBACK using DBAPI connection.rollback(), "
|
|
"DBAPI should ignore due to autocommit mode"
|
|
)
|
|
else:
|
|
self._log_info("ROLLBACK")
|
|
try:
|
|
self.engine.dialect.do_rollback(self.connection)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(e, None, None, None, None)
|
|
|
|
def _commit_impl(self, autocommit=False):
|
|
assert not self.__branch_from
|
|
|
|
# AUTOCOMMIT isolation-level is a dialect-specific concept, however
|
|
# if a connection has this set as the isolation level, we can skip
|
|
# the "autocommit" warning as the operation will do "autocommit"
|
|
# in any case
|
|
if autocommit and not self._is_autocommit_isolation():
|
|
util.warn_deprecated_20(
|
|
"The current statement is being autocommitted using "
|
|
"implicit autocommit, which will be removed in "
|
|
"SQLAlchemy 2.0. "
|
|
"Use the .begin() method of Engine or Connection in order to "
|
|
"use an explicit transaction for DML and DDL statements."
|
|
)
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.commit(self)
|
|
|
|
if self._echo:
|
|
if self._is_autocommit_isolation():
|
|
self._log_info(
|
|
"COMMIT using DBAPI connection.commit(), "
|
|
"DBAPI should ignore due to autocommit mode"
|
|
)
|
|
else:
|
|
self._log_info("COMMIT")
|
|
try:
|
|
self.engine.dialect.do_commit(self.connection)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(e, None, None, None, None)
|
|
|
|
def _savepoint_impl(self, name=None):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.savepoint(self, name)
|
|
|
|
if name is None:
|
|
self.__savepoint_seq += 1
|
|
name = "sa_savepoint_%s" % self.__savepoint_seq
|
|
if self._still_open_and_dbapi_connection_is_valid:
|
|
self.engine.dialect.do_savepoint(self, name)
|
|
return name
|
|
|
|
def _rollback_to_savepoint_impl(self, name):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.rollback_savepoint(self, name, None)
|
|
|
|
if self._still_open_and_dbapi_connection_is_valid:
|
|
self.engine.dialect.do_rollback_to_savepoint(self, name)
|
|
|
|
def _release_savepoint_impl(self, name):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.release_savepoint(self, name, None)
|
|
|
|
if self._still_open_and_dbapi_connection_is_valid:
|
|
self.engine.dialect.do_release_savepoint(self, name)
|
|
|
|
def _begin_twophase_impl(self, transaction):
|
|
assert not self.__branch_from
|
|
|
|
if self._echo:
|
|
self._log_info("BEGIN TWOPHASE (implicit)")
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.begin_twophase(self, transaction.xid)
|
|
|
|
if self._still_open_and_dbapi_connection_is_valid:
|
|
self.__in_begin = True
|
|
try:
|
|
self.engine.dialect.do_begin_twophase(self, transaction.xid)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(e, None, None, None, None)
|
|
finally:
|
|
self.__in_begin = False
|
|
|
|
def _prepare_twophase_impl(self, xid):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.prepare_twophase(self, xid)
|
|
|
|
if self._still_open_and_dbapi_connection_is_valid:
|
|
assert isinstance(self._transaction, TwoPhaseTransaction)
|
|
try:
|
|
self.engine.dialect.do_prepare_twophase(self, xid)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(e, None, None, None, None)
|
|
|
|
def _rollback_twophase_impl(self, xid, is_prepared):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.rollback_twophase(self, xid, is_prepared)
|
|
|
|
if self._still_open_and_dbapi_connection_is_valid:
|
|
assert isinstance(self._transaction, TwoPhaseTransaction)
|
|
try:
|
|
self.engine.dialect.do_rollback_twophase(
|
|
self, xid, is_prepared
|
|
)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(e, None, None, None, None)
|
|
|
|
def _commit_twophase_impl(self, xid, is_prepared):
|
|
assert not self.__branch_from
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.commit_twophase(self, xid, is_prepared)
|
|
|
|
if self._still_open_and_dbapi_connection_is_valid:
|
|
assert isinstance(self._transaction, TwoPhaseTransaction)
|
|
try:
|
|
self.engine.dialect.do_commit_twophase(self, xid, is_prepared)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(e, None, None, None, None)
|
|
|
|
def _autorollback(self):
|
|
if self.__branch_from:
|
|
self.__branch_from._autorollback()
|
|
|
|
if not self.in_transaction():
|
|
self._rollback_impl()
|
|
|
|
def _warn_for_legacy_exec_format(self):
|
|
util.warn_deprecated_20(
|
|
"The connection.execute() method in "
|
|
"SQLAlchemy 2.0 will accept parameters as a single "
|
|
"dictionary or a "
|
|
"single sequence of dictionaries only. "
|
|
"Parameters passed as keyword arguments, tuples or positionally "
|
|
"oriented dictionaries and/or tuples "
|
|
"will no longer be accepted."
|
|
)
|
|
|
|
def close(self):
|
|
"""Close this :class:`_engine.Connection`.
|
|
|
|
This results in a release of the underlying database
|
|
resources, that is, the DBAPI connection referenced
|
|
internally. The DBAPI connection is typically restored
|
|
back to the connection-holding :class:`_pool.Pool` referenced
|
|
by the :class:`_engine.Engine` that produced this
|
|
:class:`_engine.Connection`. Any transactional state present on
|
|
the DBAPI connection is also unconditionally released via
|
|
the DBAPI connection's ``rollback()`` method, regardless
|
|
of any :class:`.Transaction` object that may be
|
|
outstanding with regards to this :class:`_engine.Connection`.
|
|
|
|
After :meth:`_engine.Connection.close` is called, the
|
|
:class:`_engine.Connection` is permanently in a closed state,
|
|
and will allow no further operations.
|
|
|
|
"""
|
|
|
|
if self.__branch_from:
|
|
assert not self._is_future
|
|
util.warn_deprecated_20(
|
|
"The .close() method on a so-called 'branched' connection is "
|
|
"deprecated as of 1.4, as are 'branched' connections overall, "
|
|
"and will be removed in a future release. If this is a "
|
|
"default-handling function, don't close the connection."
|
|
)
|
|
self._dbapi_connection = None
|
|
self.__can_reconnect = False
|
|
return
|
|
|
|
if self._transaction:
|
|
self._transaction.close()
|
|
skip_reset = True
|
|
else:
|
|
skip_reset = False
|
|
|
|
if self._dbapi_connection is not None:
|
|
conn = self._dbapi_connection
|
|
|
|
# as we just closed the transaction, close the connection
|
|
# pool connection without doing an additional reset
|
|
if skip_reset:
|
|
conn._close_no_reset()
|
|
else:
|
|
conn.close()
|
|
|
|
# There is a slight chance that conn.close() may have
|
|
# triggered an invalidation here in which case
|
|
# _dbapi_connection would already be None, however usually
|
|
# it will be non-None here and in a "closed" state.
|
|
self._dbapi_connection = None
|
|
self.__can_reconnect = False
|
|
|
|
def scalar(self, object_, *multiparams, **params):
|
|
"""Executes and returns the first column of the first row.
|
|
|
|
The underlying result/cursor is closed after execution.
|
|
|
|
"""
|
|
|
|
return self.execute(object_, *multiparams, **params).scalar()
|
|
|
|
def scalars(self, object_, *multiparams, **params):
|
|
"""Executes and returns a scalar result set, which yields scalar values
|
|
from the first column of each row.
|
|
|
|
This method is equivalent to calling :meth:`_engine.Connection.execute`
|
|
to receive a :class:`_result.Result` object, then invoking the
|
|
:meth:`_result.Result.scalars` method to produce a
|
|
:class:`_result.ScalarResult` instance.
|
|
|
|
:return: a :class:`_result.ScalarResult`
|
|
|
|
.. versionadded:: 1.4.24
|
|
|
|
"""
|
|
|
|
return self.execute(object_, *multiparams, **params).scalars()
|
|
|
|
def execute(self, statement, *multiparams, **params):
|
|
r"""Executes a SQL statement construct and returns a
|
|
:class:`_engine.CursorResult`.
|
|
|
|
:param statement: The statement to be executed. May be
|
|
one of:
|
|
|
|
* a plain string (deprecated)
|
|
* any :class:`_expression.ClauseElement` construct that is also
|
|
a subclass of :class:`.Executable`, such as a
|
|
:func:`_expression.select` construct
|
|
* a :class:`.FunctionElement`, such as that generated
|
|
by :data:`.func`, will be automatically wrapped in
|
|
a SELECT statement, which is then executed.
|
|
* a :class:`.DDLElement` object
|
|
* a :class:`.DefaultGenerator` object
|
|
* a :class:`.Compiled` object
|
|
|
|
.. deprecated:: 2.0 passing a string to
|
|
:meth:`_engine.Connection.execute` is
|
|
deprecated and will be removed in version 2.0. Use the
|
|
:func:`_expression.text` construct with
|
|
:meth:`_engine.Connection.execute`, or the
|
|
:meth:`_engine.Connection.exec_driver_sql`
|
|
method to invoke a driver-level
|
|
SQL string.
|
|
|
|
:param \*multiparams/\**params: represent bound parameter
|
|
values to be used in the execution. Typically,
|
|
the format is either a collection of one or more
|
|
dictionaries passed to \*multiparams::
|
|
|
|
conn.execute(
|
|
table.insert(),
|
|
{"id":1, "value":"v1"},
|
|
{"id":2, "value":"v2"}
|
|
)
|
|
|
|
...or individual key/values interpreted by \**params::
|
|
|
|
conn.execute(
|
|
table.insert(), id=1, value="v1"
|
|
)
|
|
|
|
In the case that a plain SQL string is passed, and the underlying
|
|
DBAPI accepts positional bind parameters, a collection of tuples
|
|
or individual values in \*multiparams may be passed::
|
|
|
|
conn.execute(
|
|
"INSERT INTO table (id, value) VALUES (?, ?)",
|
|
(1, "v1"), (2, "v2")
|
|
)
|
|
|
|
conn.execute(
|
|
"INSERT INTO table (id, value) VALUES (?, ?)",
|
|
1, "v1"
|
|
)
|
|
|
|
Note above, the usage of a question mark "?" or other
|
|
symbol is contingent upon the "paramstyle" accepted by the DBAPI
|
|
in use, which may be any of "qmark", "named", "pyformat", "format",
|
|
"numeric". See `pep-249
|
|
<https://www.python.org/dev/peps/pep-0249/>`_ for details on
|
|
paramstyle.
|
|
|
|
To execute a textual SQL statement which uses bound parameters in a
|
|
DBAPI-agnostic way, use the :func:`_expression.text` construct.
|
|
|
|
.. deprecated:: 2.0 use of tuple or scalar positional parameters
|
|
is deprecated. All params should be dicts or sequences of dicts.
|
|
Use :meth:`.exec_driver_sql` to execute a plain string with
|
|
tuple or scalar positional parameters.
|
|
|
|
"""
|
|
|
|
if isinstance(statement, util.string_types):
|
|
util.warn_deprecated_20(
|
|
"Passing a string to Connection.execute() is "
|
|
"deprecated and will be removed in version 2.0. Use the "
|
|
"text() construct, "
|
|
"or the Connection.exec_driver_sql() method to invoke a "
|
|
"driver-level SQL string."
|
|
)
|
|
|
|
return self._exec_driver_sql(
|
|
statement,
|
|
multiparams,
|
|
params,
|
|
_EMPTY_EXECUTION_OPTS,
|
|
future=False,
|
|
)
|
|
|
|
try:
|
|
meth = statement._execute_on_connection
|
|
except AttributeError as err:
|
|
util.raise_(
|
|
exc.ObjectNotExecutableError(statement), replace_context=err
|
|
)
|
|
else:
|
|
return meth(self, multiparams, params, _EMPTY_EXECUTION_OPTS)
|
|
|
|
def _execute_function(self, func, multiparams, params, execution_options):
|
|
"""Execute a sql.FunctionElement object."""
|
|
|
|
return self._execute_clauseelement(
|
|
func.select(), multiparams, params, execution_options
|
|
)
|
|
|
|
def _execute_default(
|
|
self,
|
|
default,
|
|
multiparams,
|
|
params,
|
|
# migrate is calling this directly :(
|
|
execution_options=_EMPTY_EXECUTION_OPTS,
|
|
):
|
|
"""Execute a schema.ColumnDefault object."""
|
|
|
|
execution_options = self._execution_options.merge_with(
|
|
execution_options
|
|
)
|
|
|
|
distilled_parameters = _distill_params(self, multiparams, params)
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
(
|
|
default,
|
|
distilled_params,
|
|
event_multiparams,
|
|
event_params,
|
|
) = self._invoke_before_exec_event(
|
|
default, distilled_parameters, execution_options
|
|
)
|
|
|
|
try:
|
|
conn = self._dbapi_connection
|
|
if conn is None:
|
|
conn = self._revalidate_connection()
|
|
|
|
dialect = self.dialect
|
|
ctx = dialect.execution_ctx_cls._init_default(
|
|
dialect, self, conn, execution_options
|
|
)
|
|
except (exc.PendingRollbackError, exc.ResourceClosedError):
|
|
raise
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(e, None, None, None, None)
|
|
|
|
ret = ctx._exec_default(None, default, None)
|
|
if self.should_close_with_result:
|
|
self.close()
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.after_execute(
|
|
self,
|
|
default,
|
|
event_multiparams,
|
|
event_params,
|
|
execution_options,
|
|
ret,
|
|
)
|
|
|
|
return ret
|
|
|
|
def _execute_ddl(self, ddl, multiparams, params, execution_options):
|
|
"""Execute a schema.DDL object."""
|
|
|
|
execution_options = ddl._execution_options.merge_with(
|
|
self._execution_options, execution_options
|
|
)
|
|
|
|
distilled_parameters = _distill_params(self, multiparams, params)
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
(
|
|
ddl,
|
|
distilled_params,
|
|
event_multiparams,
|
|
event_params,
|
|
) = self._invoke_before_exec_event(
|
|
ddl, distilled_parameters, execution_options
|
|
)
|
|
|
|
exec_opts = self._execution_options.merge_with(execution_options)
|
|
schema_translate_map = exec_opts.get("schema_translate_map", None)
|
|
|
|
dialect = self.dialect
|
|
|
|
compiled = ddl.compile(
|
|
dialect=dialect, schema_translate_map=schema_translate_map
|
|
)
|
|
ret = self._execute_context(
|
|
dialect,
|
|
dialect.execution_ctx_cls._init_ddl,
|
|
compiled,
|
|
None,
|
|
execution_options,
|
|
compiled,
|
|
)
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.after_execute(
|
|
self,
|
|
ddl,
|
|
event_multiparams,
|
|
event_params,
|
|
execution_options,
|
|
ret,
|
|
)
|
|
return ret
|
|
|
|
def _invoke_before_exec_event(
|
|
self, elem, distilled_params, execution_options
|
|
):
|
|
|
|
if len(distilled_params) == 1:
|
|
event_multiparams, event_params = [], distilled_params[0]
|
|
else:
|
|
event_multiparams, event_params = distilled_params, {}
|
|
|
|
for fn in self.dispatch.before_execute:
|
|
elem, event_multiparams, event_params = fn(
|
|
self,
|
|
elem,
|
|
event_multiparams,
|
|
event_params,
|
|
execution_options,
|
|
)
|
|
|
|
if event_multiparams:
|
|
distilled_params = list(event_multiparams)
|
|
if event_params:
|
|
raise exc.InvalidRequestError(
|
|
"Event handler can't return non-empty multiparams "
|
|
"and params at the same time"
|
|
)
|
|
elif event_params:
|
|
distilled_params = [event_params]
|
|
else:
|
|
distilled_params = []
|
|
|
|
return elem, distilled_params, event_multiparams, event_params
|
|
|
|
def _execute_clauseelement(
|
|
self, elem, multiparams, params, execution_options
|
|
):
|
|
"""Execute a sql.ClauseElement object."""
|
|
|
|
execution_options = elem._execution_options.merge_with(
|
|
self._execution_options, execution_options
|
|
)
|
|
|
|
distilled_params = _distill_params(self, multiparams, params)
|
|
|
|
has_events = self._has_events or self.engine._has_events
|
|
if has_events:
|
|
(
|
|
elem,
|
|
distilled_params,
|
|
event_multiparams,
|
|
event_params,
|
|
) = self._invoke_before_exec_event(
|
|
elem, distilled_params, execution_options
|
|
)
|
|
|
|
if distilled_params:
|
|
# ensure we don't retain a link to the view object for keys()
|
|
# which links to the values, which we don't want to cache
|
|
keys = sorted(distilled_params[0])
|
|
for_executemany = len(distilled_params) > 1
|
|
else:
|
|
keys = []
|
|
for_executemany = False
|
|
|
|
dialect = self.dialect
|
|
|
|
schema_translate_map = execution_options.get(
|
|
"schema_translate_map", None
|
|
)
|
|
|
|
compiled_cache = execution_options.get(
|
|
"compiled_cache", self.engine._compiled_cache
|
|
)
|
|
|
|
compiled_sql, extracted_params, cache_hit = elem._compile_w_cache(
|
|
dialect=dialect,
|
|
compiled_cache=compiled_cache,
|
|
column_keys=keys,
|
|
for_executemany=for_executemany,
|
|
schema_translate_map=schema_translate_map,
|
|
linting=self.dialect.compiler_linting | compiler.WARN_LINTING,
|
|
)
|
|
ret = self._execute_context(
|
|
dialect,
|
|
dialect.execution_ctx_cls._init_compiled,
|
|
compiled_sql,
|
|
distilled_params,
|
|
execution_options,
|
|
compiled_sql,
|
|
distilled_params,
|
|
elem,
|
|
extracted_params,
|
|
cache_hit=cache_hit,
|
|
)
|
|
if has_events:
|
|
self.dispatch.after_execute(
|
|
self,
|
|
elem,
|
|
event_multiparams,
|
|
event_params,
|
|
execution_options,
|
|
ret,
|
|
)
|
|
return ret
|
|
|
|
def _execute_compiled(
|
|
self,
|
|
compiled,
|
|
multiparams,
|
|
params,
|
|
execution_options=_EMPTY_EXECUTION_OPTS,
|
|
):
|
|
"""Execute a sql.Compiled object.
|
|
|
|
TODO: why do we have this? likely deprecate or remove
|
|
|
|
"""
|
|
|
|
execution_options = compiled.execution_options.merge_with(
|
|
self._execution_options, execution_options
|
|
)
|
|
distilled_parameters = _distill_params(self, multiparams, params)
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
(
|
|
compiled,
|
|
distilled_params,
|
|
event_multiparams,
|
|
event_params,
|
|
) = self._invoke_before_exec_event(
|
|
compiled, distilled_parameters, execution_options
|
|
)
|
|
|
|
dialect = self.dialect
|
|
|
|
ret = self._execute_context(
|
|
dialect,
|
|
dialect.execution_ctx_cls._init_compiled,
|
|
compiled,
|
|
distilled_parameters,
|
|
execution_options,
|
|
compiled,
|
|
distilled_parameters,
|
|
None,
|
|
None,
|
|
)
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.after_execute(
|
|
self,
|
|
compiled,
|
|
event_multiparams,
|
|
event_params,
|
|
execution_options,
|
|
ret,
|
|
)
|
|
return ret
|
|
|
|
def _exec_driver_sql(
|
|
self, statement, multiparams, params, execution_options, future
|
|
):
|
|
|
|
execution_options = self._execution_options.merge_with(
|
|
execution_options
|
|
)
|
|
|
|
distilled_parameters = _distill_params(self, multiparams, params)
|
|
|
|
if not future:
|
|
if self._has_events or self.engine._has_events:
|
|
(
|
|
statement,
|
|
distilled_params,
|
|
event_multiparams,
|
|
event_params,
|
|
) = self._invoke_before_exec_event(
|
|
statement, distilled_parameters, execution_options
|
|
)
|
|
|
|
dialect = self.dialect
|
|
ret = self._execute_context(
|
|
dialect,
|
|
dialect.execution_ctx_cls._init_statement,
|
|
statement,
|
|
distilled_parameters,
|
|
execution_options,
|
|
statement,
|
|
distilled_parameters,
|
|
)
|
|
|
|
if not future:
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.after_execute(
|
|
self,
|
|
statement,
|
|
event_multiparams,
|
|
event_params,
|
|
execution_options,
|
|
ret,
|
|
)
|
|
return ret
|
|
|
|
def _execute_20(
|
|
self,
|
|
statement,
|
|
parameters=None,
|
|
execution_options=_EMPTY_EXECUTION_OPTS,
|
|
):
|
|
args_10style, kwargs_10style = _distill_params_20(parameters)
|
|
try:
|
|
meth = statement._execute_on_connection
|
|
except AttributeError as err:
|
|
util.raise_(
|
|
exc.ObjectNotExecutableError(statement), replace_context=err
|
|
)
|
|
else:
|
|
return meth(self, args_10style, kwargs_10style, execution_options)
|
|
|
|
def exec_driver_sql(
|
|
self, statement, parameters=None, execution_options=None
|
|
):
|
|
r"""Executes a SQL statement construct and returns a
|
|
:class:`_engine.CursorResult`.
|
|
|
|
:param statement: The statement str to be executed. Bound parameters
|
|
must use the underlying DBAPI's paramstyle, such as "qmark",
|
|
"pyformat", "format", etc.
|
|
|
|
:param parameters: represent bound parameter values to be used in the
|
|
execution. The format is one of: a dictionary of named parameters,
|
|
a tuple of positional parameters, or a list containing either
|
|
dictionaries or tuples for multiple-execute support.
|
|
|
|
E.g. multiple dictionaries::
|
|
|
|
|
|
conn.exec_driver_sql(
|
|
"INSERT INTO table (id, value) VALUES (%(id)s, %(value)s)",
|
|
[{"id":1, "value":"v1"}, {"id":2, "value":"v2"}]
|
|
)
|
|
|
|
Single dictionary::
|
|
|
|
conn.exec_driver_sql(
|
|
"INSERT INTO table (id, value) VALUES (%(id)s, %(value)s)",
|
|
dict(id=1, value="v1")
|
|
)
|
|
|
|
Single tuple::
|
|
|
|
conn.exec_driver_sql(
|
|
"INSERT INTO table (id, value) VALUES (?, ?)",
|
|
(1, 'v1')
|
|
)
|
|
|
|
.. note:: The :meth:`_engine.Connection.exec_driver_sql` method does
|
|
not participate in the
|
|
:meth:`_events.ConnectionEvents.before_execute` and
|
|
:meth:`_events.ConnectionEvents.after_execute` events. To
|
|
intercept calls to :meth:`_engine.Connection.exec_driver_sql`, use
|
|
:meth:`_events.ConnectionEvents.before_cursor_execute` and
|
|
:meth:`_events.ConnectionEvents.after_cursor_execute`.
|
|
|
|
.. seealso::
|
|
|
|
:pep:`249`
|
|
|
|
"""
|
|
|
|
args_10style, kwargs_10style = _distill_params_20(parameters)
|
|
|
|
return self._exec_driver_sql(
|
|
statement,
|
|
args_10style,
|
|
kwargs_10style,
|
|
execution_options,
|
|
future=True,
|
|
)
|
|
|
|
def _execute_context(
|
|
self,
|
|
dialect,
|
|
constructor,
|
|
statement,
|
|
parameters,
|
|
execution_options,
|
|
*args,
|
|
**kw
|
|
):
|
|
"""Create an :class:`.ExecutionContext` and execute, returning
|
|
a :class:`_engine.CursorResult`."""
|
|
|
|
branched = self
|
|
if self.__branch_from:
|
|
# if this is a "branched" connection, do everything in terms
|
|
# of the "root" connection, *except* for .close(), which is
|
|
# the only feature that branching provides
|
|
self = self.__branch_from
|
|
|
|
try:
|
|
conn = self._dbapi_connection
|
|
if conn is None:
|
|
conn = self._revalidate_connection()
|
|
|
|
context = constructor(
|
|
dialect, self, conn, execution_options, *args, **kw
|
|
)
|
|
except (exc.PendingRollbackError, exc.ResourceClosedError):
|
|
raise
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(
|
|
e, util.text_type(statement), parameters, None, None
|
|
)
|
|
|
|
if (
|
|
self._transaction
|
|
and not self._transaction.is_active
|
|
or (
|
|
self._nested_transaction
|
|
and not self._nested_transaction.is_active
|
|
)
|
|
):
|
|
self._invalid_transaction()
|
|
|
|
elif self._trans_context_manager:
|
|
TransactionalContext._trans_ctx_check(self)
|
|
|
|
if self._is_future and self._transaction is None:
|
|
self._autobegin()
|
|
|
|
context.pre_exec()
|
|
|
|
if dialect.use_setinputsizes:
|
|
context._set_input_sizes()
|
|
|
|
cursor, statement, parameters = (
|
|
context.cursor,
|
|
context.statement,
|
|
context.parameters,
|
|
)
|
|
|
|
if not context.executemany:
|
|
parameters = parameters[0]
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
for fn in self.dispatch.before_cursor_execute:
|
|
statement, parameters = fn(
|
|
self,
|
|
cursor,
|
|
statement,
|
|
parameters,
|
|
context,
|
|
context.executemany,
|
|
)
|
|
|
|
if self._echo:
|
|
|
|
self._log_info(statement)
|
|
|
|
stats = context._get_cache_stats()
|
|
|
|
if not self.engine.hide_parameters:
|
|
self._log_info(
|
|
"[%s] %r",
|
|
stats,
|
|
sql_util._repr_params(
|
|
parameters, batches=10, ismulti=context.executemany
|
|
),
|
|
)
|
|
else:
|
|
self._log_info(
|
|
"[%s] [SQL parameters hidden due to hide_parameters=True]"
|
|
% (stats,)
|
|
)
|
|
|
|
evt_handled = False
|
|
try:
|
|
if context.executemany:
|
|
if self.dialect._has_events:
|
|
for fn in self.dialect.dispatch.do_executemany:
|
|
if fn(cursor, statement, parameters, context):
|
|
evt_handled = True
|
|
break
|
|
if not evt_handled:
|
|
self.dialect.do_executemany(
|
|
cursor, statement, parameters, context
|
|
)
|
|
elif not parameters and context.no_parameters:
|
|
if self.dialect._has_events:
|
|
for fn in self.dialect.dispatch.do_execute_no_params:
|
|
if fn(cursor, statement, context):
|
|
evt_handled = True
|
|
break
|
|
if not evt_handled:
|
|
self.dialect.do_execute_no_params(
|
|
cursor, statement, context
|
|
)
|
|
else:
|
|
if self.dialect._has_events:
|
|
for fn in self.dialect.dispatch.do_execute:
|
|
if fn(cursor, statement, parameters, context):
|
|
evt_handled = True
|
|
break
|
|
if not evt_handled:
|
|
self.dialect.do_execute(
|
|
cursor, statement, parameters, context
|
|
)
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.after_cursor_execute(
|
|
self,
|
|
cursor,
|
|
statement,
|
|
parameters,
|
|
context,
|
|
context.executemany,
|
|
)
|
|
|
|
context.post_exec()
|
|
|
|
result = context._setup_result_proxy()
|
|
|
|
if not self._is_future:
|
|
should_close_with_result = branched.should_close_with_result
|
|
|
|
if not result._soft_closed and should_close_with_result:
|
|
result._autoclose_connection = True
|
|
|
|
if (
|
|
# usually we're in a transaction so avoid relatively
|
|
# expensive / legacy should_autocommit call
|
|
self._transaction is None
|
|
and context.should_autocommit
|
|
):
|
|
self._commit_impl(autocommit=True)
|
|
|
|
# for "connectionless" execution, we have to close this
|
|
# Connection after the statement is complete.
|
|
# legacy stuff.
|
|
if should_close_with_result and context._soft_closed:
|
|
assert not self._is_future
|
|
|
|
# CursorResult already exhausted rows / has no rows.
|
|
# close us now
|
|
branched.close()
|
|
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(
|
|
e, statement, parameters, cursor, context
|
|
)
|
|
|
|
return result
|
|
|
|
def _cursor_execute(self, cursor, statement, parameters, context=None):
|
|
"""Execute a statement + params on the given cursor.
|
|
|
|
Adds appropriate logging and exception handling.
|
|
|
|
This method is used by DefaultDialect for special-case
|
|
executions, such as for sequences and column defaults.
|
|
The path of statement execution in the majority of cases
|
|
terminates at _execute_context().
|
|
|
|
"""
|
|
if self._has_events or self.engine._has_events:
|
|
for fn in self.dispatch.before_cursor_execute:
|
|
statement, parameters = fn(
|
|
self, cursor, statement, parameters, context, False
|
|
)
|
|
|
|
if self._echo:
|
|
self._log_info(statement)
|
|
self._log_info("[raw sql] %r", parameters)
|
|
try:
|
|
for fn in (
|
|
()
|
|
if not self.dialect._has_events
|
|
else self.dialect.dispatch.do_execute
|
|
):
|
|
if fn(cursor, statement, parameters, context):
|
|
break
|
|
else:
|
|
self.dialect.do_execute(cursor, statement, parameters, context)
|
|
except BaseException as e:
|
|
self._handle_dbapi_exception(
|
|
e, statement, parameters, cursor, context
|
|
)
|
|
|
|
if self._has_events or self.engine._has_events:
|
|
self.dispatch.after_cursor_execute(
|
|
self, cursor, statement, parameters, context, False
|
|
)
|
|
|
|
def _safe_close_cursor(self, cursor):
|
|
"""Close the given cursor, catching exceptions
|
|
and turning into log warnings.
|
|
|
|
"""
|
|
try:
|
|
cursor.close()
|
|
except Exception:
|
|
# log the error through the connection pool's logger.
|
|
self.engine.pool.logger.error(
|
|
"Error closing cursor", exc_info=True
|
|
)
|
|
|
|
_reentrant_error = False
|
|
_is_disconnect = False
|
|
|
|
def _handle_dbapi_exception(
|
|
self, e, statement, parameters, cursor, context
|
|
):
|
|
exc_info = sys.exc_info()
|
|
|
|
is_exit_exception = util.is_exit_exception(e)
|
|
|
|
if not self._is_disconnect:
|
|
self._is_disconnect = (
|
|
isinstance(e, self.dialect.dbapi.Error)
|
|
and not self.closed
|
|
and self.dialect.is_disconnect(
|
|
e,
|
|
self._dbapi_connection if not self.invalidated else None,
|
|
cursor,
|
|
)
|
|
) or (is_exit_exception and not self.closed)
|
|
|
|
invalidate_pool_on_disconnect = not is_exit_exception
|
|
|
|
if self._reentrant_error:
|
|
util.raise_(
|
|
exc.DBAPIError.instance(
|
|
statement,
|
|
parameters,
|
|
e,
|
|
self.dialect.dbapi.Error,
|
|
hide_parameters=self.engine.hide_parameters,
|
|
dialect=self.dialect,
|
|
ismulti=context.executemany
|
|
if context is not None
|
|
else None,
|
|
),
|
|
with_traceback=exc_info[2],
|
|
from_=e,
|
|
)
|
|
self._reentrant_error = True
|
|
try:
|
|
# non-DBAPI error - if we already got a context,
|
|
# or there's no string statement, don't wrap it
|
|
should_wrap = isinstance(e, self.dialect.dbapi.Error) or (
|
|
statement is not None
|
|
and context is None
|
|
and not is_exit_exception
|
|
)
|
|
|
|
if should_wrap:
|
|
sqlalchemy_exception = exc.DBAPIError.instance(
|
|
statement,
|
|
parameters,
|
|
e,
|
|
self.dialect.dbapi.Error,
|
|
hide_parameters=self.engine.hide_parameters,
|
|
connection_invalidated=self._is_disconnect,
|
|
dialect=self.dialect,
|
|
ismulti=context.executemany
|
|
if context is not None
|
|
else None,
|
|
)
|
|
else:
|
|
sqlalchemy_exception = None
|
|
|
|
newraise = None
|
|
|
|
if (
|
|
self._has_events or self.engine._has_events
|
|
) and not self._execution_options.get(
|
|
"skip_user_error_events", False
|
|
):
|
|
ctx = ExceptionContextImpl(
|
|
e,
|
|
sqlalchemy_exception,
|
|
self.engine,
|
|
self,
|
|
cursor,
|
|
statement,
|
|
parameters,
|
|
context,
|
|
self._is_disconnect,
|
|
invalidate_pool_on_disconnect,
|
|
)
|
|
|
|
for fn in self.dispatch.handle_error:
|
|
try:
|
|
# handler returns an exception;
|
|
# call next handler in a chain
|
|
per_fn = fn(ctx)
|
|
if per_fn is not None:
|
|
ctx.chained_exception = newraise = per_fn
|
|
except Exception as _raised:
|
|
# handler raises an exception - stop processing
|
|
newraise = _raised
|
|
break
|
|
|
|
if self._is_disconnect != ctx.is_disconnect:
|
|
self._is_disconnect = ctx.is_disconnect
|
|
if sqlalchemy_exception:
|
|
sqlalchemy_exception.connection_invalidated = (
|
|
ctx.is_disconnect
|
|
)
|
|
|
|
# set up potentially user-defined value for
|
|
# invalidate pool.
|
|
invalidate_pool_on_disconnect = (
|
|
ctx.invalidate_pool_on_disconnect
|
|
)
|
|
|
|
if should_wrap and context:
|
|
context.handle_dbapi_exception(e)
|
|
|
|
if not self._is_disconnect:
|
|
if cursor:
|
|
self._safe_close_cursor(cursor)
|
|
with util.safe_reraise(warn_only=True):
|
|
self._autorollback()
|
|
|
|
if newraise:
|
|
util.raise_(newraise, with_traceback=exc_info[2], from_=e)
|
|
elif should_wrap:
|
|
util.raise_(
|
|
sqlalchemy_exception, with_traceback=exc_info[2], from_=e
|
|
)
|
|
else:
|
|
util.raise_(exc_info[1], with_traceback=exc_info[2])
|
|
|
|
finally:
|
|
del self._reentrant_error
|
|
if self._is_disconnect:
|
|
del self._is_disconnect
|
|
if not self.invalidated:
|
|
dbapi_conn_wrapper = self._dbapi_connection
|
|
if invalidate_pool_on_disconnect:
|
|
self.engine.pool._invalidate(dbapi_conn_wrapper, e)
|
|
self.invalidate(e)
|
|
if self.should_close_with_result:
|
|
assert not self._is_future
|
|
self.close()
|
|
|
|
@classmethod
|
|
def _handle_dbapi_exception_noconnection(cls, e, dialect, engine):
|
|
exc_info = sys.exc_info()
|
|
|
|
is_disconnect = dialect.is_disconnect(e, None, None)
|
|
|
|
should_wrap = isinstance(e, dialect.dbapi.Error)
|
|
|
|
if should_wrap:
|
|
sqlalchemy_exception = exc.DBAPIError.instance(
|
|
None,
|
|
None,
|
|
e,
|
|
dialect.dbapi.Error,
|
|
hide_parameters=engine.hide_parameters,
|
|
connection_invalidated=is_disconnect,
|
|
)
|
|
else:
|
|
sqlalchemy_exception = None
|
|
|
|
newraise = None
|
|
|
|
if engine._has_events:
|
|
ctx = ExceptionContextImpl(
|
|
e,
|
|
sqlalchemy_exception,
|
|
engine,
|
|
None,
|
|
None,
|
|
None,
|
|
None,
|
|
None,
|
|
is_disconnect,
|
|
True,
|
|
)
|
|
for fn in engine.dispatch.handle_error:
|
|
try:
|
|
# handler returns an exception;
|
|
# call next handler in a chain
|
|
per_fn = fn(ctx)
|
|
if per_fn is not None:
|
|
ctx.chained_exception = newraise = per_fn
|
|
except Exception as _raised:
|
|
# handler raises an exception - stop processing
|
|
newraise = _raised
|
|
break
|
|
|
|
if sqlalchemy_exception and is_disconnect != ctx.is_disconnect:
|
|
sqlalchemy_exception.connection_invalidated = (
|
|
is_disconnect
|
|
) = ctx.is_disconnect
|
|
|
|
if newraise:
|
|
util.raise_(newraise, with_traceback=exc_info[2], from_=e)
|
|
elif should_wrap:
|
|
util.raise_(
|
|
sqlalchemy_exception, with_traceback=exc_info[2], from_=e
|
|
)
|
|
else:
|
|
util.raise_(exc_info[1], with_traceback=exc_info[2])
|
|
|
|
def _run_ddl_visitor(self, visitorcallable, element, **kwargs):
|
|
"""run a DDL visitor.
|
|
|
|
This method is only here so that the MockConnection can change the
|
|
options given to the visitor so that "checkfirst" is skipped.
|
|
|
|
"""
|
|
visitorcallable(self.dialect, self, **kwargs).traverse_single(element)
|
|
|
|
@util.deprecated(
|
|
"1.4",
|
|
"The :meth:`_engine.Connection.transaction` "
|
|
"method is deprecated and will be "
|
|
"removed in a future release. Use the :meth:`_engine.Engine.begin` "
|
|
"context manager instead.",
|
|
)
|
|
def transaction(self, callable_, *args, **kwargs):
|
|
r"""Execute the given function within a transaction boundary.
|
|
|
|
The function is passed this :class:`_engine.Connection`
|
|
as the first argument, followed by the given \*args and \**kwargs,
|
|
e.g.::
|
|
|
|
def do_something(conn, x, y):
|
|
conn.execute(text("some statement"), {'x':x, 'y':y})
|
|
|
|
conn.transaction(do_something, 5, 10)
|
|
|
|
The operations inside the function are all invoked within the
|
|
context of a single :class:`.Transaction`.
|
|
Upon success, the transaction is committed. If an
|
|
exception is raised, the transaction is rolled back
|
|
before propagating the exception.
|
|
|
|
.. note::
|
|
|
|
The :meth:`.transaction` method is superseded by
|
|
the usage of the Python ``with:`` statement, which can
|
|
be used with :meth:`_engine.Connection.begin`::
|
|
|
|
with conn.begin():
|
|
conn.execute(text("some statement"), {'x':5, 'y':10})
|
|
|
|
As well as with :meth:`_engine.Engine.begin`::
|
|
|
|
with engine.begin() as conn:
|
|
conn.execute(text("some statement"), {'x':5, 'y':10})
|
|
|
|
.. seealso::
|
|
|
|
:meth:`_engine.Engine.begin` - engine-level transactional
|
|
context
|
|
|
|
:meth:`_engine.Engine.transaction` - engine-level version of
|
|
:meth:`_engine.Connection.transaction`
|
|
|
|
"""
|
|
|
|
kwargs["_sa_skip_warning"] = True
|
|
trans = self.begin()
|
|
try:
|
|
ret = self.run_callable(callable_, *args, **kwargs)
|
|
trans.commit()
|
|
return ret
|
|
except:
|
|
with util.safe_reraise():
|
|
trans.rollback()
|
|
|
|
@util.deprecated(
|
|
"1.4",
|
|
"The :meth:`_engine.Connection.run_callable` "
|
|
"method is deprecated and will "
|
|
"be removed in a future release. Invoke the callable function "
|
|
"directly, passing the Connection.",
|
|
)
|
|
def run_callable(self, callable_, *args, **kwargs):
|
|
r"""Given a callable object or function, execute it, passing
|
|
a :class:`_engine.Connection` as the first argument.
|
|
|
|
The given \*args and \**kwargs are passed subsequent
|
|
to the :class:`_engine.Connection` argument.
|
|
|
|
This function, along with :meth:`_engine.Engine.run_callable`,
|
|
allows a function to be run with a :class:`_engine.Connection`
|
|
or :class:`_engine.Engine` object without the need to know
|
|
which one is being dealt with.
|
|
|
|
"""
|
|
return callable_(self, *args, **kwargs)
|
|
|
|
|
|
class ExceptionContextImpl(ExceptionContext):
|
|
"""Implement the :class:`.ExceptionContext` interface."""
|
|
|
|
def __init__(
|
|
self,
|
|
exception,
|
|
sqlalchemy_exception,
|
|
engine,
|
|
connection,
|
|
cursor,
|
|
statement,
|
|
parameters,
|
|
context,
|
|
is_disconnect,
|
|
invalidate_pool_on_disconnect,
|
|
):
|
|
self.engine = engine
|
|
self.connection = connection
|
|
self.sqlalchemy_exception = sqlalchemy_exception
|
|
self.original_exception = exception
|
|
self.execution_context = context
|
|
self.statement = statement
|
|
self.parameters = parameters
|
|
self.is_disconnect = is_disconnect
|
|
self.invalidate_pool_on_disconnect = invalidate_pool_on_disconnect
|
|
|
|
|
|
class Transaction(TransactionalContext):
|
|
"""Represent a database transaction in progress.
|
|
|
|
The :class:`.Transaction` object is procured by
|
|
calling the :meth:`_engine.Connection.begin` method of
|
|
:class:`_engine.Connection`::
|
|
|
|
from sqlalchemy import create_engine
|
|
engine = create_engine("postgresql://scott:tiger@localhost/test")
|
|
connection = engine.connect()
|
|
trans = connection.begin()
|
|
connection.execute(text("insert into x (a, b) values (1, 2)"))
|
|
trans.commit()
|
|
|
|
The object provides :meth:`.rollback` and :meth:`.commit`
|
|
methods in order to control transaction boundaries. It
|
|
also implements a context manager interface so that
|
|
the Python ``with`` statement can be used with the
|
|
:meth:`_engine.Connection.begin` method::
|
|
|
|
with connection.begin():
|
|
connection.execute(text("insert into x (a, b) values (1, 2)"))
|
|
|
|
The Transaction object is **not** threadsafe.
|
|
|
|
.. seealso::
|
|
|
|
:meth:`_engine.Connection.begin`
|
|
|
|
:meth:`_engine.Connection.begin_twophase`
|
|
|
|
:meth:`_engine.Connection.begin_nested`
|
|
|
|
.. index::
|
|
single: thread safety; Transaction
|
|
"""
|
|
|
|
__slots__ = ()
|
|
|
|
_is_root = False
|
|
|
|
def __init__(self, connection):
|
|
raise NotImplementedError()
|
|
|
|
def _do_deactivate(self):
|
|
"""do whatever steps are necessary to set this transaction as
|
|
"deactive", however leave this transaction object in place as far
|
|
as the connection's state.
|
|
|
|
for a "real" transaction this should roll back the transaction
|
|
and ensure this transaction is no longer a reset agent.
|
|
|
|
this is used for nesting of marker transactions where the marker
|
|
can set the "real" transaction as rolled back, however it stays
|
|
in place.
|
|
|
|
for 2.0 we hope to remove this nesting feature.
|
|
|
|
"""
|
|
raise NotImplementedError()
|
|
|
|
@property
|
|
def _deactivated_from_connection(self):
|
|
"""True if this transaction is totally deactivated from the connection
|
|
and therefore can no longer affect its state.
|
|
|
|
"""
|
|
raise NotImplementedError()
|
|
|
|
def _do_close(self):
|
|
raise NotImplementedError()
|
|
|
|
def _do_rollback(self):
|
|
raise NotImplementedError()
|
|
|
|
def _do_commit(self):
|
|
raise NotImplementedError()
|
|
|
|
@property
|
|
def is_valid(self):
|
|
return self.is_active and not self.connection.invalidated
|
|
|
|
def close(self):
|
|
"""Close this :class:`.Transaction`.
|
|
|
|
If this transaction is the base transaction in a begin/commit
|
|
nesting, the transaction will rollback(). Otherwise, the
|
|
method returns.
|
|
|
|
This is used to cancel a Transaction without affecting the scope of
|
|
an enclosing transaction.
|
|
|
|
"""
|
|
try:
|
|
self._do_close()
|
|
finally:
|
|
assert not self.is_active
|
|
|
|
def rollback(self):
|
|
"""Roll back this :class:`.Transaction`.
|
|
|
|
The implementation of this may vary based on the type of transaction in
|
|
use:
|
|
|
|
* For a simple database transaction (e.g. :class:`.RootTransaction`),
|
|
it corresponds to a ROLLBACK.
|
|
|
|
* For a :class:`.NestedTransaction`, it corresponds to a
|
|
"ROLLBACK TO SAVEPOINT" operation.
|
|
|
|
* For a :class:`.TwoPhaseTransaction`, DBAPI-specific methods for two
|
|
phase transactions may be used.
|
|
|
|
|
|
"""
|
|
try:
|
|
self._do_rollback()
|
|
finally:
|
|
assert not self.is_active
|
|
|
|
def commit(self):
|
|
"""Commit this :class:`.Transaction`.
|
|
|
|
The implementation of this may vary based on the type of transaction in
|
|
use:
|
|
|
|
* For a simple database transaction (e.g. :class:`.RootTransaction`),
|
|
it corresponds to a COMMIT.
|
|
|
|
* For a :class:`.NestedTransaction`, it corresponds to a
|
|
"RELEASE SAVEPOINT" operation.
|
|
|
|
* For a :class:`.TwoPhaseTransaction`, DBAPI-specific methods for two
|
|
phase transactions may be used.
|
|
|
|
"""
|
|
try:
|
|
self._do_commit()
|
|
finally:
|
|
assert not self.is_active
|
|
|
|
def _get_subject(self):
|
|
return self.connection
|
|
|
|
def _transaction_is_active(self):
|
|
return self.is_active
|
|
|
|
def _transaction_is_closed(self):
|
|
return not self._deactivated_from_connection
|
|
|
|
def _rollback_can_be_called(self):
|
|
# for RootTransaction / NestedTransaction, it's safe to call
|
|
# rollback() even if the transaction is deactive and no warnings
|
|
# will be emitted. tested in
|
|
# test_transaction.py -> test_no_rollback_in_deactive(?:_savepoint)?
|
|
return True
|
|
|
|
|
|
class MarkerTransaction(Transaction):
|
|
"""A 'marker' transaction that is used for nested begin() calls.
|
|
|
|
.. deprecated:: 1.4 future connection for 2.0 won't support this pattern.
|
|
|
|
"""
|
|
|
|
__slots__ = ("connection", "_is_active", "_transaction")
|
|
|
|
def __init__(self, connection):
|
|
assert connection._transaction is not None
|
|
if not connection._transaction.is_active:
|
|
raise exc.InvalidRequestError(
|
|
"the current transaction on this connection is inactive. "
|
|
"Please issue a rollback first."
|
|
)
|
|
|
|
assert not connection._is_future
|
|
util.warn_deprecated_20(
|
|
"Calling .begin() when a transaction is already begun, creating "
|
|
"a 'sub' transaction, is deprecated "
|
|
"and will be removed in 2.0. See the documentation section "
|
|
"'Migrating from the nesting pattern' for background on how "
|
|
"to migrate from this pattern."
|
|
)
|
|
|
|
self.connection = connection
|
|
|
|
if connection._trans_context_manager:
|
|
TransactionalContext._trans_ctx_check(connection)
|
|
|
|
if connection._nested_transaction is not None:
|
|
self._transaction = connection._nested_transaction
|
|
else:
|
|
self._transaction = connection._transaction
|
|
self._is_active = True
|
|
|
|
@property
|
|
def _deactivated_from_connection(self):
|
|
return not self.is_active
|
|
|
|
@property
|
|
def is_active(self):
|
|
return self._is_active and self._transaction.is_active
|
|
|
|
def _deactivate(self):
|
|
self._is_active = False
|
|
|
|
def _do_close(self):
|
|
# does not actually roll back the root
|
|
self._deactivate()
|
|
|
|
def _do_rollback(self):
|
|
# does roll back the root
|
|
if self._is_active:
|
|
try:
|
|
self._transaction._do_deactivate()
|
|
finally:
|
|
self._deactivate()
|
|
|
|
def _do_commit(self):
|
|
self._deactivate()
|
|
|
|
|
|
class RootTransaction(Transaction):
|
|
"""Represent the "root" transaction on a :class:`_engine.Connection`.
|
|
|
|
This corresponds to the current "BEGIN/COMMIT/ROLLBACK" that's occurring
|
|
for the :class:`_engine.Connection`. The :class:`_engine.RootTransaction`
|
|
is created by calling upon the :meth:`_engine.Connection.begin` method, and
|
|
remains associated with the :class:`_engine.Connection` throughout its
|
|
active span. The current :class:`_engine.RootTransaction` in use is
|
|
accessible via the :attr:`_engine.Connection.get_transaction` method of
|
|
:class:`_engine.Connection`.
|
|
|
|
In :term:`2.0 style` use, the :class:`_future.Connection` also employs
|
|
"autobegin" behavior that will create a new
|
|
:class:`_engine.RootTransaction` whenever a connection in a
|
|
non-transactional state is used to emit commands on the DBAPI connection.
|
|
The scope of the :class:`_engine.RootTransaction` in 2.0 style
|
|
use can be controlled using the :meth:`_future.Connection.commit` and
|
|
:meth:`_future.Connection.rollback` methods.
|
|
|
|
|
|
"""
|
|
|
|
_is_root = True
|
|
|
|
__slots__ = ("connection", "is_active")
|
|
|
|
def __init__(self, connection):
|
|
assert connection._transaction is None
|
|
if connection._trans_context_manager:
|
|
TransactionalContext._trans_ctx_check(connection)
|
|
self.connection = connection
|
|
self._connection_begin_impl()
|
|
connection._transaction = self
|
|
|
|
self.is_active = True
|
|
|
|
def _deactivate_from_connection(self):
|
|
if self.is_active:
|
|
assert self.connection._transaction is self
|
|
self.is_active = False
|
|
|
|
elif self.connection._transaction is not self:
|
|
util.warn("transaction already deassociated from connection")
|
|
|
|
@property
|
|
def _deactivated_from_connection(self):
|
|
return self.connection._transaction is not self
|
|
|
|
def _do_deactivate(self):
|
|
# called from a MarkerTransaction to cancel this root transaction.
|
|
# the transaction stays in place as connection._transaction, but
|
|
# is no longer active and is no longer the reset agent for the
|
|
# pooled connection. the connection won't support a new begin()
|
|
# until this transaction is explicitly closed, rolled back,
|
|
# or committed.
|
|
|
|
assert self.connection._transaction is self
|
|
|
|
if self.is_active:
|
|
self._connection_rollback_impl()
|
|
|
|
# handle case where a savepoint was created inside of a marker
|
|
# transaction that refers to a root. nested has to be cancelled
|
|
# also.
|
|
if self.connection._nested_transaction:
|
|
self.connection._nested_transaction._cancel()
|
|
|
|
self._deactivate_from_connection()
|
|
|
|
def _connection_begin_impl(self):
|
|
self.connection._begin_impl(self)
|
|
|
|
def _connection_rollback_impl(self):
|
|
self.connection._rollback_impl()
|
|
|
|
def _connection_commit_impl(self):
|
|
self.connection._commit_impl()
|
|
|
|
def _close_impl(self, try_deactivate=False):
|
|
try:
|
|
if self.is_active:
|
|
self._connection_rollback_impl()
|
|
|
|
if self.connection._nested_transaction:
|
|
self.connection._nested_transaction._cancel()
|
|
finally:
|
|
if self.is_active or try_deactivate:
|
|
self._deactivate_from_connection()
|
|
if self.connection._transaction is self:
|
|
self.connection._transaction = None
|
|
|
|
assert not self.is_active
|
|
assert self.connection._transaction is not self
|
|
|
|
def _do_close(self):
|
|
self._close_impl()
|
|
|
|
def _do_rollback(self):
|
|
self._close_impl(try_deactivate=True)
|
|
|
|
def _do_commit(self):
|
|
if self.is_active:
|
|
assert self.connection._transaction is self
|
|
|
|
try:
|
|
self._connection_commit_impl()
|
|
finally:
|
|
# whether or not commit succeeds, cancel any
|
|
# nested transactions, make this transaction "inactive"
|
|
# and remove it as a reset agent
|
|
if self.connection._nested_transaction:
|
|
self.connection._nested_transaction._cancel()
|
|
|
|
self._deactivate_from_connection()
|
|
|
|
# ...however only remove as the connection's current transaction
|
|
# if commit succeeded. otherwise it stays on so that a rollback
|
|
# needs to occur.
|
|
self.connection._transaction = None
|
|
else:
|
|
if self.connection._transaction is self:
|
|
self.connection._invalid_transaction()
|
|
else:
|
|
raise exc.InvalidRequestError("This transaction is inactive")
|
|
|
|
assert not self.is_active
|
|
assert self.connection._transaction is not self
|
|
|
|
|
|
class NestedTransaction(Transaction):
|
|
"""Represent a 'nested', or SAVEPOINT transaction.
|
|
|
|
The :class:`.NestedTransaction` object is created by calling the
|
|
:meth:`_engine.Connection.begin_nested` method of
|
|
:class:`_engine.Connection`.
|
|
|
|
When using :class:`.NestedTransaction`, the semantics of "begin" /
|
|
"commit" / "rollback" are as follows:
|
|
|
|
* the "begin" operation corresponds to the "BEGIN SAVEPOINT" command, where
|
|
the savepoint is given an explicit name that is part of the state
|
|
of this object.
|
|
|
|
* The :meth:`.NestedTransaction.commit` method corresponds to a
|
|
"RELEASE SAVEPOINT" operation, using the savepoint identifier associated
|
|
with this :class:`.NestedTransaction`.
|
|
|
|
* The :meth:`.NestedTransaction.rollback` method corresponds to a
|
|
"ROLLBACK TO SAVEPOINT" operation, using the savepoint identifier
|
|
associated with this :class:`.NestedTransaction`.
|
|
|
|
The rationale for mimicking the semantics of an outer transaction in
|
|
terms of savepoints so that code may deal with a "savepoint" transaction
|
|
and an "outer" transaction in an agnostic way.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`session_begin_nested` - ORM version of the SAVEPOINT API.
|
|
|
|
"""
|
|
|
|
__slots__ = ("connection", "is_active", "_savepoint", "_previous_nested")
|
|
|
|
def __init__(self, connection):
|
|
assert connection._transaction is not None
|
|
if connection._trans_context_manager:
|
|
TransactionalContext._trans_ctx_check(connection)
|
|
self.connection = connection
|
|
self._savepoint = self.connection._savepoint_impl()
|
|
self.is_active = True
|
|
self._previous_nested = connection._nested_transaction
|
|
connection._nested_transaction = self
|
|
|
|
def _deactivate_from_connection(self, warn=True):
|
|
if self.connection._nested_transaction is self:
|
|
self.connection._nested_transaction = self._previous_nested
|
|
elif warn:
|
|
util.warn(
|
|
"nested transaction already deassociated from connection"
|
|
)
|
|
|
|
@property
|
|
def _deactivated_from_connection(self):
|
|
return self.connection._nested_transaction is not self
|
|
|
|
def _cancel(self):
|
|
# called by RootTransaction when the outer transaction is
|
|
# committed, rolled back, or closed to cancel all savepoints
|
|
# without any action being taken
|
|
self.is_active = False
|
|
self._deactivate_from_connection()
|
|
if self._previous_nested:
|
|
self._previous_nested._cancel()
|
|
|
|
def _close_impl(self, deactivate_from_connection, warn_already_deactive):
|
|
try:
|
|
if self.is_active and self.connection._transaction.is_active:
|
|
self.connection._rollback_to_savepoint_impl(self._savepoint)
|
|
finally:
|
|
self.is_active = False
|
|
|
|
if deactivate_from_connection:
|
|
self._deactivate_from_connection(warn=warn_already_deactive)
|
|
|
|
assert not self.is_active
|
|
if deactivate_from_connection:
|
|
assert self.connection._nested_transaction is not self
|
|
|
|
def _do_deactivate(self):
|
|
self._close_impl(False, False)
|
|
|
|
def _do_close(self):
|
|
self._close_impl(True, False)
|
|
|
|
def _do_rollback(self):
|
|
self._close_impl(True, True)
|
|
|
|
def _do_commit(self):
|
|
if self.is_active:
|
|
try:
|
|
self.connection._release_savepoint_impl(self._savepoint)
|
|
finally:
|
|
# nested trans becomes inactive on failed release
|
|
# unconditionally. this prevents it from trying to
|
|
# emit SQL when it rolls back.
|
|
self.is_active = False
|
|
|
|
# but only de-associate from connection if it succeeded
|
|
self._deactivate_from_connection()
|
|
else:
|
|
if self.connection._nested_transaction is self:
|
|
self.connection._invalid_transaction()
|
|
else:
|
|
raise exc.InvalidRequestError(
|
|
"This nested transaction is inactive"
|
|
)
|
|
|
|
|
|
class TwoPhaseTransaction(RootTransaction):
|
|
"""Represent a two-phase transaction.
|
|
|
|
A new :class:`.TwoPhaseTransaction` object may be procured
|
|
using the :meth:`_engine.Connection.begin_twophase` method.
|
|
|
|
The interface is the same as that of :class:`.Transaction`
|
|
with the addition of the :meth:`prepare` method.
|
|
|
|
"""
|
|
|
|
__slots__ = ("connection", "is_active", "xid", "_is_prepared")
|
|
|
|
def __init__(self, connection, xid):
|
|
self._is_prepared = False
|
|
self.xid = xid
|
|
super(TwoPhaseTransaction, self).__init__(connection)
|
|
|
|
def prepare(self):
|
|
"""Prepare this :class:`.TwoPhaseTransaction`.
|
|
|
|
After a PREPARE, the transaction can be committed.
|
|
|
|
"""
|
|
if not self.is_active:
|
|
raise exc.InvalidRequestError("This transaction is inactive")
|
|
self.connection._prepare_twophase_impl(self.xid)
|
|
self._is_prepared = True
|
|
|
|
def _connection_begin_impl(self):
|
|
self.connection._begin_twophase_impl(self)
|
|
|
|
def _connection_rollback_impl(self):
|
|
self.connection._rollback_twophase_impl(self.xid, self._is_prepared)
|
|
|
|
def _connection_commit_impl(self):
|
|
self.connection._commit_twophase_impl(self.xid, self._is_prepared)
|
|
|
|
|
|
class Engine(Connectable, log.Identified):
|
|
"""
|
|
Connects a :class:`~sqlalchemy.pool.Pool` and
|
|
:class:`~sqlalchemy.engine.interfaces.Dialect` together to provide a
|
|
source of database connectivity and behavior.
|
|
|
|
This is the **SQLAlchemy 1.x version** of :class:`_engine.Engine`. For
|
|
the :term:`2.0 style` version, which includes some API differences,
|
|
see :class:`_future.Engine`.
|
|
|
|
An :class:`_engine.Engine` object is instantiated publicly using the
|
|
:func:`~sqlalchemy.create_engine` function.
|
|
|
|
.. seealso::
|
|
|
|
:doc:`/core/engines`
|
|
|
|
:ref:`connections_toplevel`
|
|
|
|
"""
|
|
|
|
_execution_options = _EMPTY_EXECUTION_OPTS
|
|
_has_events = False
|
|
_connection_cls = Connection
|
|
_sqla_logger_namespace = "sqlalchemy.engine.Engine"
|
|
_is_future = False
|
|
|
|
_schema_translate_map = None
|
|
|
|
def __init__(
|
|
self,
|
|
pool,
|
|
dialect,
|
|
url,
|
|
logging_name=None,
|
|
echo=None,
|
|
query_cache_size=500,
|
|
execution_options=None,
|
|
hide_parameters=False,
|
|
):
|
|
self.pool = pool
|
|
self.url = url
|
|
self.dialect = dialect
|
|
if logging_name:
|
|
self.logging_name = logging_name
|
|
self.echo = echo
|
|
self.hide_parameters = hide_parameters
|
|
if query_cache_size != 0:
|
|
self._compiled_cache = util.LRUCache(
|
|
query_cache_size, size_alert=self._lru_size_alert
|
|
)
|
|
else:
|
|
self._compiled_cache = None
|
|
log.instance_logger(self, echoflag=echo)
|
|
if execution_options:
|
|
self.update_execution_options(**execution_options)
|
|
|
|
def _lru_size_alert(self, cache):
|
|
if self._should_log_info:
|
|
self.logger.info(
|
|
"Compiled cache size pruning from %d items to %d. "
|
|
"Increase cache size to reduce the frequency of pruning.",
|
|
len(cache),
|
|
cache.capacity,
|
|
)
|
|
|
|
@property
|
|
def engine(self):
|
|
return self
|
|
|
|
def clear_compiled_cache(self):
|
|
"""Clear the compiled cache associated with the dialect.
|
|
|
|
This applies **only** to the built-in cache that is established
|
|
via the :paramref:`_engine.create_engine.query_cache_size` parameter.
|
|
It will not impact any dictionary caches that were passed via the
|
|
:paramref:`.Connection.execution_options.query_cache` parameter.
|
|
|
|
.. versionadded:: 1.4
|
|
|
|
"""
|
|
if self._compiled_cache:
|
|
self._compiled_cache.clear()
|
|
|
|
def update_execution_options(self, **opt):
|
|
r"""Update the default execution_options dictionary
|
|
of this :class:`_engine.Engine`.
|
|
|
|
The given keys/values in \**opt are added to the
|
|
default execution options that will be used for
|
|
all connections. The initial contents of this dictionary
|
|
can be sent via the ``execution_options`` parameter
|
|
to :func:`_sa.create_engine`.
|
|
|
|
.. seealso::
|
|
|
|
:meth:`_engine.Connection.execution_options`
|
|
|
|
:meth:`_engine.Engine.execution_options`
|
|
|
|
"""
|
|
self._execution_options = self._execution_options.union(opt)
|
|
self.dispatch.set_engine_execution_options(self, opt)
|
|
self.dialect.set_engine_execution_options(self, opt)
|
|
|
|
def execution_options(self, **opt):
|
|
"""Return a new :class:`_engine.Engine` that will provide
|
|
:class:`_engine.Connection` objects with the given execution options.
|
|
|
|
The returned :class:`_engine.Engine` remains related to the original
|
|
:class:`_engine.Engine` in that it shares the same connection pool and
|
|
other state:
|
|
|
|
* The :class:`_pool.Pool` used by the new :class:`_engine.Engine`
|
|
is the
|
|
same instance. The :meth:`_engine.Engine.dispose`
|
|
method will replace
|
|
the connection pool instance for the parent engine as well
|
|
as this one.
|
|
* Event listeners are "cascaded" - meaning, the new
|
|
:class:`_engine.Engine`
|
|
inherits the events of the parent, and new events can be associated
|
|
with the new :class:`_engine.Engine` individually.
|
|
* The logging configuration and logging_name is copied from the parent
|
|
:class:`_engine.Engine`.
|
|
|
|
The intent of the :meth:`_engine.Engine.execution_options` method is
|
|
to implement "sharding" schemes where multiple :class:`_engine.Engine`
|
|
objects refer to the same connection pool, but are differentiated
|
|
by options that would be consumed by a custom event::
|
|
|
|
primary_engine = create_engine("mysql://")
|
|
shard1 = primary_engine.execution_options(shard_id="shard1")
|
|
shard2 = primary_engine.execution_options(shard_id="shard2")
|
|
|
|
Above, the ``shard1`` engine serves as a factory for
|
|
:class:`_engine.Connection`
|
|
objects that will contain the execution option
|
|
``shard_id=shard1``, and ``shard2`` will produce
|
|
:class:`_engine.Connection`
|
|
objects that contain the execution option ``shard_id=shard2``.
|
|
|
|
An event handler can consume the above execution option to perform
|
|
a schema switch or other operation, given a connection. Below
|
|
we emit a MySQL ``use`` statement to switch databases, at the same
|
|
time keeping track of which database we've established using the
|
|
:attr:`_engine.Connection.info` dictionary,
|
|
which gives us a persistent
|
|
storage space that follows the DBAPI connection::
|
|
|
|
from sqlalchemy import event
|
|
from sqlalchemy.engine import Engine
|
|
|
|
shards = {"default": "base", shard_1: "db1", "shard_2": "db2"}
|
|
|
|
@event.listens_for(Engine, "before_cursor_execute")
|
|
def _switch_shard(conn, cursor, stmt,
|
|
params, context, executemany):
|
|
shard_id = conn._execution_options.get('shard_id', "default")
|
|
current_shard = conn.info.get("current_shard", None)
|
|
|
|
if current_shard != shard_id:
|
|
cursor.execute("use %s" % shards[shard_id])
|
|
conn.info["current_shard"] = shard_id
|
|
|
|
.. seealso::
|
|
|
|
:meth:`_engine.Connection.execution_options`
|
|
- update execution options
|
|
on a :class:`_engine.Connection` object.
|
|
|
|
:meth:`_engine.Engine.update_execution_options`
|
|
- update the execution
|
|
options for a given :class:`_engine.Engine` in place.
|
|
|
|
:meth:`_engine.Engine.get_execution_options`
|
|
|
|
|
|
"""
|
|
return self._option_cls(self, opt)
|
|
|
|
def get_execution_options(self):
|
|
"""Get the non-SQL options which will take effect during execution.
|
|
|
|
.. versionadded: 1.3
|
|
|
|
.. seealso::
|
|
|
|
:meth:`_engine.Engine.execution_options`
|
|
"""
|
|
return self._execution_options
|
|
|
|
@property
|
|
def name(self):
|
|
"""String name of the :class:`~sqlalchemy.engine.interfaces.Dialect`
|
|
in use by this :class:`Engine`."""
|
|
|
|
return self.dialect.name
|
|
|
|
@property
|
|
def driver(self):
|
|
"""Driver name of the :class:`~sqlalchemy.engine.interfaces.Dialect`
|
|
in use by this :class:`Engine`."""
|
|
|
|
return self.dialect.driver
|
|
|
|
echo = log.echo_property()
|
|
|
|
def __repr__(self):
|
|
return "Engine(%r)" % (self.url,)
|
|
|
|
def dispose(self, close=True):
|
|
"""Dispose of the connection pool used by this
|
|
:class:`_engine.Engine`.
|
|
|
|
A new connection pool is created immediately after the old one has been
|
|
disposed. The previous connection pool is disposed either actively, by
|
|
closing out all currently checked-in connections in that pool, or
|
|
passively, by losing references to it but otherwise not closing any
|
|
connections. The latter strategy is more appropriate for an initializer
|
|
in a forked Python process.
|
|
|
|
:param close: if left at its default of ``True``, has the
|
|
effect of fully closing all **currently checked in**
|
|
database connections. Connections that are still checked out
|
|
will **not** be closed, however they will no longer be associated
|
|
with this :class:`_engine.Engine`,
|
|
so when they are closed individually, eventually the
|
|
:class:`_pool.Pool` which they are associated with will
|
|
be garbage collected and they will be closed out fully, if
|
|
not already closed on checkin.
|
|
|
|
If set to ``False``, the previous connection pool is de-referenced,
|
|
and otherwise not touched in any way.
|
|
|
|
.. versionadded:: 1.4.33 Added the :paramref:`.Engine.dispose.close`
|
|
parameter to allow the replacement of a connection pool in a child
|
|
process without interfering with the connections used by the parent
|
|
process.
|
|
|
|
|
|
.. seealso::
|
|
|
|
:ref:`engine_disposal`
|
|
|
|
:ref:`pooling_multiprocessing`
|
|
|
|
"""
|
|
if close:
|
|
self.pool.dispose()
|
|
self.pool = self.pool.recreate()
|
|
self.dispatch.engine_disposed(self)
|
|
|
|
def _execute_default(
|
|
self, default, multiparams=(), params=util.EMPTY_DICT
|
|
):
|
|
with self.connect() as conn:
|
|
return conn._execute_default(default, multiparams, params)
|
|
|
|
@contextlib.contextmanager
|
|
def _optional_conn_ctx_manager(self, connection=None):
|
|
if connection is None:
|
|
with self.connect() as conn:
|
|
yield conn
|
|
else:
|
|
yield connection
|
|
|
|
class _trans_ctx(object):
|
|
def __init__(self, conn, transaction, close_with_result):
|
|
self.conn = conn
|
|
self.transaction = transaction
|
|
self.close_with_result = close_with_result
|
|
|
|
def __enter__(self):
|
|
self.transaction.__enter__()
|
|
return self.conn
|
|
|
|
def __exit__(self, type_, value, traceback):
|
|
try:
|
|
self.transaction.__exit__(type_, value, traceback)
|
|
finally:
|
|
if not self.close_with_result:
|
|
self.conn.close()
|
|
|
|
def begin(self, close_with_result=False):
|
|
"""Return a context manager delivering a :class:`_engine.Connection`
|
|
with a :class:`.Transaction` established.
|
|
|
|
E.g.::
|
|
|
|
with engine.begin() as conn:
|
|
conn.execute(
|
|
text("insert into table (x, y, z) values (1, 2, 3)")
|
|
)
|
|
conn.execute(text("my_special_procedure(5)"))
|
|
|
|
Upon successful operation, the :class:`.Transaction`
|
|
is committed. If an error is raised, the :class:`.Transaction`
|
|
is rolled back.
|
|
|
|
Legacy use only: the ``close_with_result`` flag is normally ``False``,
|
|
and indicates that the :class:`_engine.Connection` will be closed when
|
|
the operation is complete. When set to ``True``, it indicates the
|
|
:class:`_engine.Connection` is in "single use" mode, where the
|
|
:class:`_engine.CursorResult` returned by the first call to
|
|
:meth:`_engine.Connection.execute` will close the
|
|
:class:`_engine.Connection` when that :class:`_engine.CursorResult` has
|
|
exhausted all result rows.
|
|
|
|
.. seealso::
|
|
|
|
:meth:`_engine.Engine.connect` - procure a
|
|
:class:`_engine.Connection` from
|
|
an :class:`_engine.Engine`.
|
|
|
|
:meth:`_engine.Connection.begin` - start a :class:`.Transaction`
|
|
for a particular :class:`_engine.Connection`.
|
|
|
|
"""
|
|
if self._connection_cls._is_future:
|
|
conn = self.connect()
|
|
else:
|
|
conn = self.connect(close_with_result=close_with_result)
|
|
try:
|
|
trans = conn.begin()
|
|
except:
|
|
with util.safe_reraise():
|
|
conn.close()
|
|
return Engine._trans_ctx(conn, trans, close_with_result)
|
|
|
|
@util.deprecated(
|
|
"1.4",
|
|
"The :meth:`_engine.Engine.transaction` "
|
|
"method is deprecated and will be "
|
|
"removed in a future release. Use the :meth:`_engine.Engine.begin` "
|
|
"context "
|
|
"manager instead.",
|
|
)
|
|
def transaction(self, callable_, *args, **kwargs):
|
|
r"""Execute the given function within a transaction boundary.
|
|
|
|
The function is passed a :class:`_engine.Connection` newly procured
|
|
from :meth:`_engine.Engine.connect` as the first argument,
|
|
followed by the given \*args and \**kwargs.
|
|
|
|
e.g.::
|
|
|
|
def do_something(conn, x, y):
|
|
conn.execute(text("some statement"), {'x':x, 'y':y})
|
|
|
|
engine.transaction(do_something, 5, 10)
|
|
|
|
The operations inside the function are all invoked within the
|
|
context of a single :class:`.Transaction`.
|
|
Upon success, the transaction is committed. If an
|
|
exception is raised, the transaction is rolled back
|
|
before propagating the exception.
|
|
|
|
.. note::
|
|
|
|
The :meth:`.transaction` method is superseded by
|
|
the usage of the Python ``with:`` statement, which can
|
|
be used with :meth:`_engine.Engine.begin`::
|
|
|
|
with engine.begin() as conn:
|
|
conn.execute(text("some statement"), {'x':5, 'y':10})
|
|
|
|
.. seealso::
|
|
|
|
:meth:`_engine.Engine.begin` - engine-level transactional
|
|
context
|
|
|
|
:meth:`_engine.Connection.transaction`
|
|
- connection-level version of
|
|
:meth:`_engine.Engine.transaction`
|
|
|
|
"""
|
|
kwargs["_sa_skip_warning"] = True
|
|
with self.connect() as conn:
|
|
return conn.transaction(callable_, *args, **kwargs)
|
|
|
|
@util.deprecated(
|
|
"1.4",
|
|
"The :meth:`_engine.Engine.run_callable` "
|
|
"method is deprecated and will be "
|
|
"removed in a future release. Use the :meth:`_engine.Engine.begin` "
|
|
"context manager instead.",
|
|
)
|
|
def run_callable(self, callable_, *args, **kwargs):
|
|
r"""Given a callable object or function, execute it, passing
|
|
a :class:`_engine.Connection` as the first argument.
|
|
|
|
The given \*args and \**kwargs are passed subsequent
|
|
to the :class:`_engine.Connection` argument.
|
|
|
|
This function, along with :meth:`_engine.Connection.run_callable`,
|
|
allows a function to be run with a :class:`_engine.Connection`
|
|
or :class:`_engine.Engine` object without the need to know
|
|
which one is being dealt with.
|
|
|
|
"""
|
|
kwargs["_sa_skip_warning"] = True
|
|
with self.connect() as conn:
|
|
return conn.run_callable(callable_, *args, **kwargs)
|
|
|
|
def _run_ddl_visitor(self, visitorcallable, element, **kwargs):
|
|
with self.begin() as conn:
|
|
conn._run_ddl_visitor(visitorcallable, element, **kwargs)
|
|
|
|
@util.deprecated_20(
|
|
":meth:`_engine.Engine.execute`",
|
|
alternative="All statement execution in SQLAlchemy 2.0 is performed "
|
|
"by the :meth:`_engine.Connection.execute` method of "
|
|
":class:`_engine.Connection`, "
|
|
"or in the ORM by the :meth:`.Session.execute` method of "
|
|
":class:`.Session`.",
|
|
)
|
|
def execute(self, statement, *multiparams, **params):
|
|
"""Executes the given construct and returns a
|
|
:class:`_engine.CursorResult`.
|
|
|
|
The arguments are the same as those used by
|
|
:meth:`_engine.Connection.execute`.
|
|
|
|
Here, a :class:`_engine.Connection` is acquired using the
|
|
:meth:`_engine.Engine.connect` method, and the statement executed
|
|
with that connection. The returned :class:`_engine.CursorResult`
|
|
is flagged
|
|
such that when the :class:`_engine.CursorResult` is exhausted and its
|
|
underlying cursor is closed, the :class:`_engine.Connection`
|
|
created here
|
|
will also be closed, which allows its associated DBAPI connection
|
|
resource to be returned to the connection pool.
|
|
|
|
"""
|
|
connection = self.connect(close_with_result=True)
|
|
return connection.execute(statement, *multiparams, **params)
|
|
|
|
@util.deprecated_20(
|
|
":meth:`_engine.Engine.scalar`",
|
|
alternative="All statement execution in SQLAlchemy 2.0 is performed "
|
|
"by the :meth:`_engine.Connection.execute` method of "
|
|
":class:`_engine.Connection`, "
|
|
"or in the ORM by the :meth:`.Session.execute` method of "
|
|
":class:`.Session`; the :meth:`_future.Result.scalar` "
|
|
"method can then be "
|
|
"used to return a scalar result.",
|
|
)
|
|
def scalar(self, statement, *multiparams, **params):
|
|
"""Executes and returns the first column of the first row.
|
|
|
|
The underlying result/cursor is closed after execution.
|
|
"""
|
|
return self.execute(statement, *multiparams, **params).scalar()
|
|
|
|
def _execute_clauseelement(
|
|
self,
|
|
elem,
|
|
multiparams=None,
|
|
params=None,
|
|
execution_options=_EMPTY_EXECUTION_OPTS,
|
|
):
|
|
connection = self.connect(close_with_result=True)
|
|
return connection._execute_clauseelement(
|
|
elem, multiparams, params, execution_options
|
|
)
|
|
|
|
def _execute_compiled(
|
|
self,
|
|
compiled,
|
|
multiparams,
|
|
params,
|
|
execution_options=_EMPTY_EXECUTION_OPTS,
|
|
):
|
|
connection = self.connect(close_with_result=True)
|
|
return connection._execute_compiled(
|
|
compiled, multiparams, params, execution_options
|
|
)
|
|
|
|
def connect(self, close_with_result=False):
|
|
"""Return a new :class:`_engine.Connection` object.
|
|
|
|
The :class:`_engine.Connection` object is a facade that uses a DBAPI
|
|
connection internally in order to communicate with the database. This
|
|
connection is procured from the connection-holding :class:`_pool.Pool`
|
|
referenced by this :class:`_engine.Engine`. When the
|
|
:meth:`_engine.Connection.close` method of the
|
|
:class:`_engine.Connection` object
|
|
is called, the underlying DBAPI connection is then returned to the
|
|
connection pool, where it may be used again in a subsequent call to
|
|
:meth:`_engine.Engine.connect`.
|
|
|
|
"""
|
|
|
|
return self._connection_cls(self, close_with_result=close_with_result)
|
|
|
|
@util.deprecated(
|
|
"1.4",
|
|
"The :meth:`_engine.Engine.table_names` "
|
|
"method is deprecated and will be "
|
|
"removed in a future release. Please refer to "
|
|
":meth:`_reflection.Inspector.get_table_names`.",
|
|
)
|
|
def table_names(self, schema=None, connection=None):
|
|
"""Return a list of all table names available in the database.
|
|
|
|
:param schema: Optional, retrieve names from a non-default schema.
|
|
|
|
:param connection: Optional, use a specified connection.
|
|
"""
|
|
with self._optional_conn_ctx_manager(connection) as conn:
|
|
insp = inspection.inspect(conn)
|
|
return insp.get_table_names(schema)
|
|
|
|
@util.deprecated(
|
|
"1.4",
|
|
"The :meth:`_engine.Engine.has_table` "
|
|
"method is deprecated and will be "
|
|
"removed in a future release. Please refer to "
|
|
":meth:`_reflection.Inspector.has_table`.",
|
|
)
|
|
def has_table(self, table_name, schema=None):
|
|
"""Return True if the given backend has a table of the given name.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`metadata_reflection_inspector` - detailed schema inspection
|
|
using the :class:`_reflection.Inspector` interface.
|
|
|
|
:class:`.quoted_name` - used to pass quoting information along
|
|
with a schema identifier.
|
|
|
|
"""
|
|
with self._optional_conn_ctx_manager(None) as conn:
|
|
insp = inspection.inspect(conn)
|
|
return insp.has_table(table_name, schema=schema)
|
|
|
|
def _wrap_pool_connect(self, fn, connection):
|
|
dialect = self.dialect
|
|
try:
|
|
return fn()
|
|
except dialect.dbapi.Error as e:
|
|
if connection is None:
|
|
Connection._handle_dbapi_exception_noconnection(
|
|
e, dialect, self
|
|
)
|
|
else:
|
|
util.raise_(
|
|
sys.exc_info()[1], with_traceback=sys.exc_info()[2]
|
|
)
|
|
|
|
def raw_connection(self, _connection=None):
|
|
"""Return a "raw" DBAPI connection from the connection pool.
|
|
|
|
The returned object is a proxied version of the DBAPI
|
|
connection object used by the underlying driver in use.
|
|
The object will have all the same behavior as the real DBAPI
|
|
connection, except that its ``close()`` method will result in the
|
|
connection being returned to the pool, rather than being closed
|
|
for real.
|
|
|
|
This method provides direct DBAPI connection access for
|
|
special situations when the API provided by
|
|
:class:`_engine.Connection`
|
|
is not needed. When a :class:`_engine.Connection` object is already
|
|
present, the DBAPI connection is available using
|
|
the :attr:`_engine.Connection.connection` accessor.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`dbapi_connections`
|
|
|
|
"""
|
|
return self._wrap_pool_connect(self.pool.connect, _connection)
|
|
|
|
|
|
class OptionEngineMixin(object):
|
|
_sa_propagate_class_events = False
|
|
|
|
def __init__(self, proxied, execution_options):
|
|
self._proxied = proxied
|
|
self.url = proxied.url
|
|
self.dialect = proxied.dialect
|
|
self.logging_name = proxied.logging_name
|
|
self.echo = proxied.echo
|
|
self._compiled_cache = proxied._compiled_cache
|
|
self.hide_parameters = proxied.hide_parameters
|
|
log.instance_logger(self, echoflag=self.echo)
|
|
|
|
# note: this will propagate events that are assigned to the parent
|
|
# engine after this OptionEngine is created. Since we share
|
|
# the events of the parent we also disallow class-level events
|
|
# to apply to the OptionEngine class directly.
|
|
#
|
|
# the other way this can work would be to transfer existing
|
|
# events only, using:
|
|
# self.dispatch._update(proxied.dispatch)
|
|
#
|
|
# that might be more appropriate however it would be a behavioral
|
|
# change for logic that assigns events to the parent engine and
|
|
# would like it to take effect for the already-created sub-engine.
|
|
self.dispatch = self.dispatch._join(proxied.dispatch)
|
|
|
|
self._execution_options = proxied._execution_options
|
|
self.update_execution_options(**execution_options)
|
|
|
|
def _get_pool(self):
|
|
return self._proxied.pool
|
|
|
|
def _set_pool(self, pool):
|
|
self._proxied.pool = pool
|
|
|
|
pool = property(_get_pool, _set_pool)
|
|
|
|
def _get_has_events(self):
|
|
return self._proxied._has_events or self.__dict__.get(
|
|
"_has_events", False
|
|
)
|
|
|
|
def _set_has_events(self, value):
|
|
self.__dict__["_has_events"] = value
|
|
|
|
_has_events = property(_get_has_events, _set_has_events)
|
|
|
|
|
|
class OptionEngine(OptionEngineMixin, Engine):
|
|
pass
|
|
|
|
|
|
Engine._option_cls = OptionEngine
|