- Repaired the :class:`.ExcludeConstraint` construct to support common

features that other objects like :class:`.Index` now do, that
the column expression may be specified as an arbitrary SQL
expression such as :obj:`.cast` or :obj:`.text`.
fixes #3454

1 files changed, 30 insertions, 7 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/constraints.py b/lib/sqlalchemy/dialects/postgresql/constraints.py
index 0371daf3d..4cfc050de 100644
--- a/lib/sqlalchemy/dialects/postgresql/constraints.py
+++ b/lib/sqlalchemy/dialects/postgresql/constraints.py
@@ -3,8 +3,9 @@
 #
 # This module is part of SQLAlchemy and is released under
 # the MIT License: http://www.opensource.org/licenses/mit-license.php
-from sqlalchemy.schema import ColumnCollectionConstraint
-from sqlalchemy.sql import expression
+from ...sql.schema import ColumnCollectionConstraint
+from ...sql import expression
+from ... import util
 
 
 class ExcludeConstraint(ColumnCollectionConstraint):
@@ -48,17 +49,39 @@ static/sql-createtable.html#SQL-CREATETABLE-EXCLUDE
           for this constraint.
 
         """
+        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_text(expr)
+
+            render_exprs.append(
+                (expr, name, operator)
+            )
+
+        self._render_exprs = render_exprs
         ColumnCollectionConstraint.__init__(
             self,
-            *[col for col, op in elements],
+            *columns,
             name=kw.get('name'),
             deferrable=kw.get('deferrable'),
             initially=kw.get('initially')
         )
-        self.operators = {}
-        for col_or_string, op in elements:
-            name = getattr(col_or_string, 'name', col_or_string)
-            self.operators[name] = op
         self.using = kw.get('using', 'gist')
         where = kw.get('where')
         if where: