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