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Diffstat (limited to 'lib/sqlalchemy/dialects/sqlite/dml.py')
| -rw-r--r-- | lib/sqlalchemy/dialects/sqlite/dml.py | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/lib/sqlalchemy/dialects/sqlite/dml.py b/lib/sqlalchemy/dialects/sqlite/dml.py new file mode 100644 index 0000000..b04a5e6 --- /dev/null +++ b/lib/sqlalchemy/dialects/sqlite/dml.py @@ -0,0 +1,200 @@ +# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors +# <see AUTHORS file> +# +# This module is part of SQLAlchemy and is released under +# the MIT License: https://www.opensource.org/licenses/mit-license.php + +from ... import util +from ...sql import coercions +from ...sql import roles +from ...sql.base import _exclusive_against +from ...sql.base import _generative +from ...sql.base import ColumnCollection +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" + inherit_cache = False + + @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. + + .. tip:: The :attr:`_sqlite.Insert.excluded` attribute is an instance + of :class:`_expression.ColumnCollection`, which provides an + interface the same as that of the :attr:`_schema.Table.c` + collection described at :ref:`metadata_tables_and_columns`. + With this collection, ordinary names are accessible like attributes + (e.g. ``stmt.excluded.some_column``), but special names and + dictionary method names should be accessed using indexed access, + such as ``stmt.excluded["column name"]`` or + ``stmt.excluded["values"]``. See the docstring for + :class:`_expression.ColumnCollection` for further examples. + + """ + return alias(self.table, name="excluded").columns + + _on_conflict_exclusive = _exclusive_against( + "_post_values_clause", + msgs={ + "_post_values_clause": "This Insert construct already has " + "an ON CONFLICT clause established" + }, + ) + + @_generative + @_on_conflict_exclusive + 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\_: + A dictionary or other mapping object + where the keys are either names of columns in the target table, + or :class:`_schema.Column` objects or other ORM-mapped columns + matching that of the target table, and expressions or literals + as values, specifying the ``SET`` actions to take. + + .. versionadded:: 1.4 The + :paramref:`_sqlite.Insert.on_conflict_do_update.set_` + parameter supports :class:`_schema.Column` objects from the target + :class:`_schema.Table` as keys. + + .. 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 + @_on_conflict_exclusive + 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 isinstance(set_, dict): + if not set_: + raise ValueError("set parameter dictionary must not be empty") + elif isinstance(set_, ColumnCollection): + set_ = dict(set_) + else: + raise ValueError( + "set parameter must be a non-empty dictionary " + "or a ColumnCollection such as the `.c.` collection " + "of a Table object" + ) + self.update_values_to_set = [ + (coercions.expect(roles.DMLColumnRole, key), value) + for key, value in set_.items() + ] + self.update_whereclause = where |