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# postgresql/ext.py # Copyright (C) 2005-2021 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 .array import ARRAY from ...sql import elements from ...sql import expression from ...sql import functions from ...sql import schema from ...sql.schema import ColumnCollectionConstraint
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"
def __init__(self, target, *order_by): self.target = elements._literal_as_binds(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 = elements._literal_as_binds(order_by[0]) else: self.order_by = elements.ClauseList( *order_by, _literal_as_text=elements._literal_as_binds )
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 `postgres documentation`__.
__ http://www.postgresql.org/docs/9.0/static/sql-createtable.html#SQL-CREATETABLE-EXCLUDE
""" # noqa
__visit_name__ = "exclude_constraint"
where = None
@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 <value> when issuing DDL for this constraint.
:param using: Optional string. If set, emit USING <index_method> when issuing DDL for this constraint. Defaults to 'gist'.
:param where: Optional SQL expression construct or literal SQL string. If set, emit WHERE <predicate> 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 <postgresql_operator_classes>` 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( self._extract_col_expression_collection(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
expr = expression._literal_as_column(expr)
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 = expression._literal_as_text( where, allow_coercion_to_text=True )
self.ops = kw.get("ops", {})
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)
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