From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Sat, 12 Aug 2006 21:08:31 +0000 (+0000)
Subject: improved error message when a backref conflicts with a column-based property
X-Git-Tag: rel_0_2_7~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=605ed429cd7992e3080f8293ce62c98c9c766475;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

improved error message when a backref conflicts with a column-based property
---

diff --git a/lib/sqlalchemy/orm/properties.py b/lib/sqlalchemy/orm/properties.py
index 26717fb659..5551348747 100644
--- a/lib/sqlalchemy/orm/properties.py
+++ b/lib/sqlalchemy/orm/properties.py
@@ -717,6 +717,8 @@ class BackRef(object):
             parent = prop.parent.primary_mapper()
             relation = cls(parent, prop.secondary, pj, sj, backref=prop.key, is_backref=True, **self.kwargs)
             mapper._compile_property(self.key, relation);
+        elif not isinstance(mapper.props[self.key], PropertyLoader):
+            raise exceptions.ArgumentError("Cant create backref '%s' on mapper '%s'; an incompatible property of that name already exists" % (self.key, str(mapper)))
         else:
             # else set one of us as the "backreference"
             parent = prop.parent.primary_mapper()
diff --git a/test/orm/mapper.py b/test/orm/mapper.py
index 5cf665fd41..49b5a0cbcb 100644
--- a/test/orm/mapper.py
+++ b/test/orm/mapper.py
@@ -101,6 +101,21 @@ class MapperTest(MapperSuperTest):
         finally:
             table.drop()
 
+    def testpropconflict(self):
+        """test that a backref created against an existing mapper with a property name
+        conflict raises a decent error message"""
+        mapper(Address, addresses)
+        mapper(User, users,
+            properties={
+            'addresses':relation(Address, backref='email_address')
+        })
+        try:
+            class_mapper(Address)
+            class_mapper(User)
+            assert False
+        except exceptions.ArgumentError:
+            pass
+        
     def testrefresh(self):
         mapper(User, users, properties={'addresses':relation(mapper(Address, addresses))})
         s = create_session()