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# Copyright (C) 2005-2020 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
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):
"""SQLite-specific implementation of INSERT.
Adds methods for SQLite-specific syntaxes such as ON CONFLICT.
The :class:`_sqlite.Insert` object is created using the
:func:`sqlalchemy.dialects.sqlite.insert` function.
.. versionadded:: 1.4
.. seealso::
:ref:`sqlite_on_conflict_insert`
"""
stringify_dialect = "sqlite"
@util.memoized_property
def excluded(self):
"""Provide the ``excluded`` namespace for an ON CONFLICT statement
SQLite's ON CONFLICT clause allows reference to the row that would
be inserted, known as ``excluded``. This attribute provides
all columns in this row to be referenceable.
"""
return alias(self.table, name="excluded").columns
@_generative
def on_conflict_do_update(
self,
index_elements=None,
index_where=None,
set_=None,
where=None,
):
r"""
Specifies a DO UPDATE SET action for ON CONFLICT clause.
:param index_elements:
A sequence consisting of string column names, :class:`_schema.Column`
objects, or other column expression objects that will be used
to infer a target index or unique constraint.
:param index_where:
Additional WHERE criterion that can be used to infer a
conditional target index.
:param set\_:
Required argument. A dictionary or other mapping object
with column names as keys and expressions or literals as values,
specifying the ``SET`` actions to take.
If the target :class:`_schema.Column` specifies a ".
key" attribute distinct
from the column name, that key should be used.
.. 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 CONFLICT style of
UPDATE, unless they are manually specified in the
:paramref:`.Insert.on_conflict_do_update.set_` dictionary.
:param where:
Optional argument. If present, can be a literal SQL
string or an acceptable expression for a ``WHERE`` clause
that restricts the rows affected by ``DO UPDATE SET``. Rows
not meeting the ``WHERE`` condition will not be updated
(effectively a ``DO NOTHING`` for those rows).
"""
self._post_values_clause = OnConflictDoUpdate(
index_elements, index_where, set_, where
)
@_generative
def on_conflict_do_nothing(self, index_elements=None, index_where=None):
"""
Specifies a DO NOTHING action for ON CONFLICT clause.
:param index_elements:
A sequence consisting of string column names, :class:`_schema.Column`
objects, or other column expression objects that will be used
to infer a target index or unique constraint.
:param index_where:
Additional WHERE criterion that can be used to infer a
conditional target index.
"""
self._post_values_clause = OnConflictDoNothing(
index_elements, index_where
)
insert = public_factory(
Insert, ".dialects.sqlite.insert", ".dialects.sqlite.Insert"
)
class OnConflictClause(ClauseElement):
stringify_dialect = "sqlite"
def __init__(self, index_elements=None, index_where=None):
if index_elements is not None:
self.constraint_target = None
self.inferred_target_elements = index_elements
self.inferred_target_whereclause = index_where
else:
self.constraint_target = (
self.inferred_target_elements
) = self.inferred_target_whereclause = None
class OnConflictDoNothing(OnConflictClause):
__visit_name__ = "on_conflict_do_nothing"
class OnConflictDoUpdate(OnConflictClause):
__visit_name__ = "on_conflict_do_update"
def __init__(
self,
index_elements=None,
index_where=None,
set_=None,
where=None,
):
super(OnConflictDoUpdate, self).__init__(
index_elements=index_elements,
index_where=index_where,
)
if not isinstance(set_, dict) or not set_:
raise ValueError("set parameter must be a non-empty dictionary")
self.update_values_to_set = [
(key, value) for key, value in set_.items()
]
self.update_whereclause = where
|
