Add opsclass to exclusion constraint

Added new parameter :paramref:`_postgresql.ExcludeConstraint.ops` to the
:class:`_postgresql.ExcludeConstraint` object, to support operator class
specification with this constraint.  Pull request courtesy Alon Menczer.

Fixes: #5604
Closes: #5700
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5700
Pull-request-sha: f8613e100792fc0bb3cf300ec6aebc78ecdf0361

Change-Id: Iaf664131ec84f8c2fb05edf799198b8d3bb83597

1 files changed, 19 insertions, 2 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/ext.py b/lib/sqlalchemy/dialects/postgresql/ext.py
index 78d9a96b6..4c8c3fc22 100644
--- a/lib/sqlalchemy/dialects/postgresql/ext.py
+++ b/lib/sqlalchemy/dialects/postgresql/ext.py
@@ -114,7 +114,8 @@ class ExcludeConstraint(ColumnCollectionConstraint):
             const = ExcludeConstraint(
                 (Column('period'), '&&'),
                 (Column('group'), '='),
-                where=(Column('group') != 'some group')
+                where=(Column('group') != 'some group'),
+                ops={'group': 'my_operator_class'}
             )
 
         The constraint is normally embedded into the :class:`_schema.Table`
@@ -133,7 +134,8 @@ class ExcludeConstraint(ColumnCollectionConstraint):
                     (some_table.c.period, '&&'),
                     (some_table.c.group, '='),
                     where=some_table.c.group != 'some group',
-                    name='some_table_excl_const'
+                    name='some_table_excl_const',
+                    ops={'group': 'my_operator_class'}
                 )
             )
 
@@ -171,6 +173,19 @@ class ExcludeConstraint(ColumnCollectionConstraint):
           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 = []
@@ -209,6 +224,8 @@ class ExcludeConstraint(ColumnCollectionConstraint):
         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)