From 05ddecb207eb6716bdafa53d70a1547e63fc49e3 Mon Sep 17 00:00:00 2001
From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Sun, 28 Jun 2009 22:46:08 +0000
Subject: [PATCH] add some goodies to help migrate

---
 lib/sqlalchemy/schema.py       | 14 +++++++++++++-
 lib/sqlalchemy/sql/compiler.py |  5 +++--
 test/sql/test_constraints.py   |  5 +++++
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/lib/sqlalchemy/schema.py b/lib/sqlalchemy/schema.py
index d85f36b39e..838daed45b 100644
--- a/lib/sqlalchemy/schema.py
+++ b/lib/sqlalchemy/schema.py
@@ -1380,7 +1380,15 @@ class ForeignKeyConstraint(Constraint):
 
         if table:
             self._set_parent(table)
-
+    
+    @property
+    def columns(self):
+        return self._elements.keys()
+        
+    @property
+    def elements(self):
+        return self._elements.values()
+        
     def _set_parent(self, table):
         super(ForeignKeyConstraint, self)._set_parent(table)
         for col, fk in self._elements.iteritems():
@@ -2140,6 +2148,10 @@ class DropConstraint(_CreateDropBase):
     """Represent an ALTER TABLE DROP CONSTRAINT statement."""
 
     __visit_name__ = "drop_constraint"
+    
+    def __init__(self, element, cascade=False, **kw):
+        self.cascade = cascade
+        super(DropConstraint, self).__init__(element, **kw)
 
 def _bind_or_error(schemaitem):
     bind = schemaitem.bind
diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 679187fe61..1a88680478 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -914,9 +914,10 @@ class DDLCompiler(engine.Compiled):
         
     def visit_drop_constraint(self, drop):
         preparer = self.preparer
-        return "ALTER TABLE %s DROP CONSTRAINT %s" % (
+        return "ALTER TABLE %s DROP CONSTRAINT %s%s" % (
             self.preparer.format_table(drop.element.table),
-            self.preparer.format_constraint(drop.element)
+            self.preparer.format_constraint(drop.element),
+            " CASCADE" if drop.cascade else ""
         )
     
     def get_column_specification(self, column, **kwargs):
diff --git a/test/sql/test_constraints.py b/test/sql/test_constraints.py
index 6188357c35..1ad03f357b 100644
--- a/test/sql/test_constraints.py
+++ b/test/sql/test_constraints.py
@@ -326,6 +326,11 @@ class ConstraintCompilationTest(TestBase, AssertsCompiledSQL):
             "ALTER TABLE tbl DROP CONSTRAINT my_test_constraint"
         )
 
+        self.assert_compile(
+            schema.DropConstraint(constraint, cascade=True),
+            "ALTER TABLE tbl DROP CONSTRAINT my_test_constraint CASCADE"
+        )
+
         constraint = ForeignKeyConstraint(["b"], ["t2.a"])
         t.append_constraint(constraint)
         self.assert_compile(
-- 
2.47.3