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205 lines
6.4 KiB
205 lines
6.4 KiB
# orm/exc.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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"""SQLAlchemy ORM exceptions."""
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from .. import exc as sa_exc
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from .. import util
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from ..exc import MultipleResultsFound # noqa
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from ..exc import NoResultFound # noqa
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NO_STATE = (AttributeError, KeyError)
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"""Exception types that may be raised by instrumentation implementations."""
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class StaleDataError(sa_exc.SQLAlchemyError):
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"""An operation encountered database state that is unaccounted for.
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Conditions which cause this to happen include:
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* A flush may have attempted to update or delete rows
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and an unexpected number of rows were matched during
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the UPDATE or DELETE statement. Note that when
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version_id_col is used, rows in UPDATE or DELETE statements
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are also matched against the current known version
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identifier.
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* A mapped object with version_id_col was refreshed,
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and the version number coming back from the database does
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not match that of the object itself.
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* A object is detached from its parent object, however
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the object was previously attached to a different parent
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identity which was garbage collected, and a decision
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cannot be made if the new parent was really the most
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recent "parent".
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"""
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ConcurrentModificationError = StaleDataError
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class FlushError(sa_exc.SQLAlchemyError):
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"""A invalid condition was detected during flush()."""
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class UnmappedError(sa_exc.InvalidRequestError):
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"""Base for exceptions that involve expected mappings not present."""
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class ObjectDereferencedError(sa_exc.SQLAlchemyError):
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"""An operation cannot complete due to an object being garbage
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collected.
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"""
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class DetachedInstanceError(sa_exc.SQLAlchemyError):
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"""An attempt to access unloaded attributes on a
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mapped instance that is detached."""
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code = "bhk3"
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class UnmappedInstanceError(UnmappedError):
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"""An mapping operation was requested for an unknown instance."""
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@util.preload_module("sqlalchemy.orm.base")
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def __init__(self, obj, msg=None):
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base = util.preloaded.orm_base
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if not msg:
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try:
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base.class_mapper(type(obj))
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name = _safe_cls_name(type(obj))
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msg = (
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"Class %r is mapped, but this instance lacks "
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"instrumentation. This occurs when the instance "
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"is created before sqlalchemy.orm.mapper(%s) "
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"was called." % (name, name)
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)
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except UnmappedClassError:
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msg = _default_unmapped(type(obj))
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if isinstance(obj, type):
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msg += (
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"; was a class (%s) supplied where an instance was "
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"required?" % _safe_cls_name(obj)
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)
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UnmappedError.__init__(self, msg)
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def __reduce__(self):
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return self.__class__, (None, self.args[0])
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class UnmappedClassError(UnmappedError):
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"""An mapping operation was requested for an unknown class."""
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def __init__(self, cls, msg=None):
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if not msg:
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msg = _default_unmapped(cls)
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UnmappedError.__init__(self, msg)
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def __reduce__(self):
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return self.__class__, (None, self.args[0])
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class ObjectDeletedError(sa_exc.InvalidRequestError):
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"""A refresh operation failed to retrieve the database
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row corresponding to an object's known primary key identity.
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A refresh operation proceeds when an expired attribute is
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accessed on an object, or when :meth:`_query.Query.get` is
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used to retrieve an object which is, upon retrieval, detected
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as expired. A SELECT is emitted for the target row
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based on primary key; if no row is returned, this
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exception is raised.
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The true meaning of this exception is simply that
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no row exists for the primary key identifier associated
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with a persistent object. The row may have been
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deleted, or in some cases the primary key updated
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to a new value, outside of the ORM's management of the target
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object.
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"""
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@util.preload_module("sqlalchemy.orm.base")
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def __init__(self, state, msg=None):
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base = util.preloaded.orm_base
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if not msg:
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msg = (
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"Instance '%s' has been deleted, or its "
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"row is otherwise not present." % base.state_str(state)
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)
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sa_exc.InvalidRequestError.__init__(self, msg)
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def __reduce__(self):
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return self.__class__, (None, self.args[0])
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class UnmappedColumnError(sa_exc.InvalidRequestError):
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"""Mapping operation was requested on an unknown column."""
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class LoaderStrategyException(sa_exc.InvalidRequestError):
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"""A loader strategy for an attribute does not exist."""
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def __init__(
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self,
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applied_to_property_type,
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requesting_property,
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applies_to,
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actual_strategy_type,
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strategy_key,
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):
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if actual_strategy_type is None:
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sa_exc.InvalidRequestError.__init__(
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self,
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"Can't find strategy %s for %s"
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% (strategy_key, requesting_property),
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)
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else:
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sa_exc.InvalidRequestError.__init__(
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self,
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'Can\'t apply "%s" strategy to property "%s", '
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'which is a "%s"; this loader strategy is intended '
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'to be used with a "%s".'
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% (
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util.clsname_as_plain_name(actual_strategy_type),
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requesting_property,
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util.clsname_as_plain_name(applied_to_property_type),
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util.clsname_as_plain_name(applies_to),
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),
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)
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def _safe_cls_name(cls):
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try:
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cls_name = ".".join((cls.__module__, cls.__name__))
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except AttributeError:
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cls_name = getattr(cls, "__name__", None)
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if cls_name is None:
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cls_name = repr(cls)
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return cls_name
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@util.preload_module("sqlalchemy.orm.base")
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def _default_unmapped(cls):
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base = util.preloaded.orm_base
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try:
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mappers = base.manager_of_class(cls).mappers
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except (TypeError,) + NO_STATE:
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mappers = {}
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name = _safe_cls_name(cls)
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if not mappers:
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return "Class '%s' is not mapped" % name
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