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# postgresql/ext.py
# Copyright (C) 2005-2015 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 ...sql import expression
from ...sql import elements
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
.. seealso::
:class:`.array_agg`
"""
__visit_name__ = 'aggregate_order_by'
def __init__(self, target, order_by):
self.target = elements._literal_as_binds(target)
self.order_by = elements._literal_as_binds(order_by)
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
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