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175 lines
6.1 KiB
175 lines
6.1 KiB
from ... import exc
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from ... import util
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from ...sql.base import _exclusive_against
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from ...sql.base import _generative
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from ...sql.base import ColumnCollection
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from ...sql.dml import Insert as StandardInsert
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from ...sql.elements import ClauseElement
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from ...sql.expression import alias
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from ...util.langhelpers import public_factory
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__all__ = ("Insert", "insert")
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class Insert(StandardInsert):
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"""MySQL-specific implementation of INSERT.
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Adds methods for MySQL-specific syntaxes such as ON DUPLICATE KEY UPDATE.
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The :class:`~.mysql.Insert` object is created using the
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:func:`sqlalchemy.dialects.mysql.insert` function.
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.. versionadded:: 1.2
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"""
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stringify_dialect = "mysql"
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inherit_cache = False
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@property
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def inserted(self):
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"""Provide the "inserted" namespace for an ON DUPLICATE KEY UPDATE statement
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MySQL's ON DUPLICATE KEY UPDATE clause allows reference to the row
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that would be inserted, via a special function called ``VALUES()``.
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This attribute provides all columns in this row to be referenceable
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such that they will render within a ``VALUES()`` function inside the
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ON DUPLICATE KEY UPDATE clause. The attribute is named ``.inserted``
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so as not to conflict with the existing
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:meth:`_expression.Insert.values` method.
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.. tip:: The :attr:`_mysql.Insert.inserted` attribute is an instance
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of :class:`_expression.ColumnCollection`, which provides an
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interface the same as that of the :attr:`_schema.Table.c`
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collection described at :ref:`metadata_tables_and_columns`.
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With this collection, ordinary names are accessible like attributes
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(e.g. ``stmt.inserted.some_column``), but special names and
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dictionary method names should be accessed using indexed access,
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such as ``stmt.inserted["column name"]`` or
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``stmt.inserted["values"]``. See the docstring for
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:class:`_expression.ColumnCollection` for further examples.
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.. seealso::
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:ref:`mysql_insert_on_duplicate_key_update` - example of how
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to use :attr:`_expression.Insert.inserted`
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"""
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return self.inserted_alias.columns
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@util.memoized_property
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def inserted_alias(self):
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return alias(self.table, name="inserted")
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@_generative
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@_exclusive_against(
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"_post_values_clause",
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msgs={
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"_post_values_clause": "This Insert construct already "
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"has an ON DUPLICATE KEY clause present"
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},
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)
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def on_duplicate_key_update(self, *args, **kw):
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r"""
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Specifies the ON DUPLICATE KEY UPDATE clause.
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:param \**kw: Column keys linked to UPDATE values. The
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values may be any SQL expression or supported literal Python
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values.
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.. warning:: This dictionary does **not** take into account
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Python-specified default UPDATE values or generation functions,
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e.g. those specified using :paramref:`_schema.Column.onupdate`.
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These values will not be exercised for an ON DUPLICATE KEY UPDATE
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style of UPDATE, unless values are manually specified here.
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:param \*args: As an alternative to passing key/value parameters,
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a dictionary or list of 2-tuples can be passed as a single positional
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argument.
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Passing a single dictionary is equivalent to the keyword argument
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form::
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insert().on_duplicate_key_update({"name": "some name"})
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Passing a list of 2-tuples indicates that the parameter assignments
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in the UPDATE clause should be ordered as sent, in a manner similar
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to that described for the :class:`_expression.Update`
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construct overall
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in :ref:`updates_order_parameters`::
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insert().on_duplicate_key_update(
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[("name", "some name"), ("value", "some value")])
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.. versionchanged:: 1.3 parameters can be specified as a dictionary
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or list of 2-tuples; the latter form provides for parameter
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ordering.
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.. versionadded:: 1.2
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.. seealso::
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:ref:`mysql_insert_on_duplicate_key_update`
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"""
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if args and kw:
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raise exc.ArgumentError(
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"Can't pass kwargs and positional arguments simultaneously"
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)
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if args:
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if len(args) > 1:
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raise exc.ArgumentError(
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"Only a single dictionary or list of tuples "
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"is accepted positionally."
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)
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values = args[0]
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else:
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values = kw
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inserted_alias = getattr(self, "inserted_alias", None)
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self._post_values_clause = OnDuplicateClause(inserted_alias, values)
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insert = public_factory(
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Insert, ".dialects.mysql.insert", ".dialects.mysql.Insert"
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)
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class OnDuplicateClause(ClauseElement):
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__visit_name__ = "on_duplicate_key_update"
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_parameter_ordering = None
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stringify_dialect = "mysql"
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def __init__(self, inserted_alias, update):
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self.inserted_alias = inserted_alias
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# auto-detect that parameters should be ordered. This is copied from
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# Update._proces_colparams(), however we don't look for a special flag
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# in this case since we are not disambiguating from other use cases as
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# we are in Update.values().
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if isinstance(update, list) and (
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update and isinstance(update[0], tuple)
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):
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self._parameter_ordering = [key for key, value in update]
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update = dict(update)
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if isinstance(update, dict):
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if not update:
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raise ValueError(
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"update parameter dictionary must not be empty"
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)
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elif isinstance(update, ColumnCollection):
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update = dict(update)
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else:
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raise ValueError(
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"update parameter must be a non-empty dictionary "
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"or a ColumnCollection such as the `.c.` collection "
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"of a Table object"
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)
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self.update = update
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