# postgresql/ext.py # Copyright (C) 2005-2023 the SQLAlchemy authors and contributors # # # This module is part of SQLAlchemy and is released under # the MIT License: https://www.opensource.org/licenses/mit-license.php from .array import ARRAY from ... import util from ...sql import coercions from ...sql import elements from ...sql import expression from ...sql import functions from ...sql import roles from ...sql import schema from ...sql.schema import ColumnCollectionConstraint from ...sql.visitors import InternalTraversal class aggregate_order_by(expression.ColumnElement): """Represent a PostgreSQL aggregate order by expression. E.g.:: from sqlalchemy.dialects.postgresql import aggregate_order_by expr = func.array_agg(aggregate_order_by(table.c.a, table.c.b.desc())) stmt = select(expr) would represent the expression:: SELECT array_agg(a ORDER BY b DESC) FROM table; Similarly:: expr = func.string_agg( table.c.a, aggregate_order_by(literal_column("','"), table.c.a) ) stmt = select(expr) Would represent:: SELECT string_agg(a, ',' ORDER BY a) FROM table; .. versionadded:: 1.1 .. versionchanged:: 1.2.13 - the ORDER BY argument may be multiple terms .. seealso:: :class:`_functions.array_agg` """ __visit_name__ = "aggregate_order_by" stringify_dialect = "postgresql" _traverse_internals = [ ("target", InternalTraversal.dp_clauseelement), ("type", InternalTraversal.dp_type), ("order_by", InternalTraversal.dp_clauseelement), ] def __init__(self, target, *order_by): self.target = coercions.expect(roles.ExpressionElementRole, target) self.type = self.target.type _lob = len(order_by) if _lob == 0: raise TypeError("at least one ORDER BY element is required") elif _lob == 1: self.order_by = coercions.expect( roles.ExpressionElementRole, order_by[0] ) else: self.order_by = elements.ClauseList( *order_by, _literal_as_text_role=roles.ExpressionElementRole ) def self_group(self, against=None): return self def get_children(self, **kwargs): return self.target, self.order_by def _copy_internals(self, clone=elements._clone, **kw): self.target = clone(self.target, **kw) self.order_by = clone(self.order_by, **kw) @property def _from_objects(self): return self.target._from_objects + self.order_by._from_objects class ExcludeConstraint(ColumnCollectionConstraint): """A table-level EXCLUDE constraint. Defines an EXCLUDE constraint as described in the `PostgreSQL documentation`__. __ https://www.postgresql.org/docs/current/static/sql-createtable.html#SQL-CREATETABLE-EXCLUDE """ # noqa __visit_name__ = "exclude_constraint" where = None inherit_cache = False create_drop_stringify_dialect = "postgresql" @elements._document_text_coercion( "where", ":class:`.ExcludeConstraint`", ":paramref:`.ExcludeConstraint.where`", ) def __init__(self, *elements, **kw): r""" Create an :class:`.ExcludeConstraint` object. E.g.:: const = ExcludeConstraint( (Column('period'), '&&'), (Column('group'), '='), where=(Column('group') != 'some group'), ops={'group': 'my_operator_class'} ) The constraint is normally embedded into the :class:`_schema.Table` construct directly, or added later using :meth:`.append_constraint`:: some_table = Table( 'some_table', metadata, Column('id', Integer, primary_key=True), Column('period', TSRANGE()), Column('group', String) ) some_table.append_constraint( ExcludeConstraint( (some_table.c.period, '&&'), (some_table.c.group, '='), where=some_table.c.group != 'some group', name='some_table_excl_const', ops={'group': 'my_operator_class'} ) ) :param \*elements: A sequence of two tuples of the form ``(column, operator)`` where "column" is a SQL expression element or a raw SQL string, most typically a :class:`_schema.Column` object, and "operator" is a string containing the operator to use. In order to specify a column name when a :class:`_schema.Column` object is not available, while ensuring that any necessary quoting rules take effect, an ad-hoc :class:`_schema.Column` or :func:`_expression.column` object should be used. :param name: Optional, the in-database name of this constraint. :param deferrable: Optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when issuing DDL for this constraint. :param initially: Optional string. If set, emit INITIALLY when issuing DDL for this constraint. :param using: Optional string. If set, emit USING when issuing DDL for this constraint. Defaults to 'gist'. :param where: Optional SQL expression construct or literal SQL string. If set, emit WHERE when issuing DDL for this constraint. :param ops: Optional dictionary. Used to define operator classes for the elements; works the same way as that of the :ref:`postgresql_ops ` parameter specified to the :class:`_schema.Index` construct. .. versionadded:: 1.3.21 .. seealso:: :ref:`postgresql_operator_classes` - general description of how PostgreSQL operator classes are specified. """ columns = [] render_exprs = [] self.operators = {} expressions, operators = zip(*elements) for (expr, column, strname, add_element), operator in zip( coercions.expect_col_expression_collection( roles.DDLConstraintColumnRole, expressions ), operators, ): if add_element is not None: columns.append(add_element) name = column.name if column is not None else strname if name is not None: # backwards compat self.operators[name] = operator render_exprs.append((expr, name, operator)) self._render_exprs = render_exprs ColumnCollectionConstraint.__init__( self, *columns, name=kw.get("name"), deferrable=kw.get("deferrable"), initially=kw.get("initially") ) self.using = kw.get("using", "gist") where = kw.get("where") if where is not None: self.where = coercions.expect(roles.StatementOptionRole, where) self.ops = kw.get("ops", {}) def _set_parent(self, table, **kw): super(ExcludeConstraint, self)._set_parent(table) self._render_exprs = [ ( expr if isinstance(expr, elements.ClauseElement) else colexpr, name, operator, ) for (expr, name, operator), colexpr in util.zip_longest( self._render_exprs, self.columns ) ] def _copy(self, target_table=None, **kw): elements = [ ( schema._copy_expression(expr, self.parent, target_table), self.operators[expr.name], ) for expr in self.columns ] c = self.__class__( *elements, name=self.name, deferrable=self.deferrable, initially=self.initially, where=self.where, using=self.using ) c.dispatch._update(self.dispatch) return c def array_agg(*arg, **kw): """PostgreSQL-specific form of :class:`_functions.array_agg`, ensures return type is :class:`_postgresql.ARRAY` and not the plain :class:`_types.ARRAY`, unless an explicit ``type_`` is passed. .. versionadded:: 1.1 """ kw["_default_array_type"] = ARRAY return functions.func.array_agg(*arg, **kw)