Current File : /lib64/python2.7/site-packages/sqlalchemy/dialects/postgresql//ext.py
# dialects/postgresql/ext.py
# Copyright (C) 2005-2024 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 .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 <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(
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)
