temporary check for unmapped class, until [ticket:1142] is resolved

2 files changed, 8 insertions, 1 deletions

diff --git a/lib/sqlalchemy/orm/properties.py b/lib/sqlalchemy/orm/properties.py
index 4056c2ff9..ebe61b19e 100644
--- a/lib/sqlalchemy/orm/properties.py
+++ b/lib/sqlalchemy/orm/properties.py
@@ -530,7 +530,9 @@ class PropertyLoader(StrategizedProperty):
             self.mapper = mapper.class_mapper(self.argument(), compile=False)
         else:
             raise sa_exc.ArgumentError("relation '%s' expects a class or a mapper argument (received: %s)" % (self.key, type(self.argument)))
-        assert isinstance(self.mapper, mapper.Mapper), self.mapper
+
+        # TODO: an informative assertion ?
+        assert isinstance(self.mapper, mapper.Mapper)
 
         # accept callables for other attributes which may require deferred initialization
         for attr in ('order_by', 'primaryjoin', 'secondaryjoin', 'secondary', '_foreign_keys', 'remote_side'):
diff --git a/lib/sqlalchemy/orm/util.py b/lib/sqlalchemy/orm/util.py
index 928b38fd3..4915d930d 100644
--- a/lib/sqlalchemy/orm/util.py
+++ b/lib/sqlalchemy/orm/util.py
@@ -464,6 +464,11 @@ def class_mapper(class_, compile=True, raiseerror=True):
     try:
         class_manager = attributes.manager_of_class(class_)
         mapper = class_manager.mapper
+        
+        # HACK until [ticket:1142] is complete
+        if mapper is None:
+            raise exc.NO_STATE
+            
     except exc.NO_STATE:
         if not raiseerror:
             return