- Specifying a non-column based argument

for column_mapped_collection, including string,
text() etc., will raise an error message that
specifically asks for a column element, no longer
misleads with incorrect information about
text() or literal().  [ticket:1863]

2 files changed, 9 insertions, 1 deletions

diff --git a/lib/sqlalchemy/orm/collections.py b/lib/sqlalchemy/orm/collections.py
index 0ea17cd8b..b5c4353b3 100644
--- a/lib/sqlalchemy/orm/collections.py
+++ b/lib/sqlalchemy/orm/collections.py
@@ -129,7 +129,7 @@ def column_mapped_collection(mapping_spec):
     from sqlalchemy.orm.util import _state_mapper
     from sqlalchemy.orm.attributes import instance_state
 
-    cols = [expression._no_literals(q) for q in util.to_list(mapping_spec)]
+    cols = [expression._only_column_elements(q) for q in util.to_list(mapping_spec)]
     if len(cols) == 1:
         def keyfunc(value):
             state = instance_state(value)
diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py
index 96147a94a..8a92dba0d 100644
--- a/lib/sqlalchemy/sql/expression.py
+++ b/lib/sqlalchemy/sql/expression.py
@@ -1035,6 +1035,14 @@ def _no_literals(element):
     else:
         return element
 
+def _only_column_elements(element):
+    if hasattr(element, '__clause_element__'):
+        element = element.__clause_element__()
+    if not isinstance(element, ColumnElement):
+        raise exc.ArgumentError("Column-based expression object expected; "
+                                "got: %r" % element)
+    return element
+    
 def _corresponding_column_or_error(fromclause, column, require_embedded=False):
     c = fromclause.corresponding_column(column,
             require_embedded=require_embedded)