- Similarly, for relationship(), foreign_keys,

remote_side, order_by - all column-based
expressions are enforced - lists of strings
are explicitly disallowed since this is a
very common error

3 files changed, 11 insertions, 9 deletions

diff --git a/lib/sqlalchemy/orm/collections.py b/lib/sqlalchemy/orm/collections.py
index b5c4353b3..a9ad34239 100644
--- a/lib/sqlalchemy/orm/collections.py
+++ b/lib/sqlalchemy/orm/collections.py
@@ -129,7 +129,8 @@ def column_mapped_collection(mapping_spec):
     from sqlalchemy.orm.util import _state_mapper
     from sqlalchemy.orm.attributes import instance_state
 
-    cols = [expression._only_column_elements(q) for q in util.to_list(mapping_spec)]
+    cols = [expression._only_column_elements(q, "mapping_spec") 
+                for q in util.to_list(mapping_spec)]
     if len(cols) == 1:
         def keyfunc(value):
             state = instance_state(value)
diff --git a/lib/sqlalchemy/orm/properties.py b/lib/sqlalchemy/orm/properties.py
index 5788c30f9..7e19d7b16 100644
--- a/lib/sqlalchemy/orm/properties.py
+++ b/lib/sqlalchemy/orm/properties.py
@@ -926,16 +926,17 @@ class RelationshipProperty(StrategizedProperty):
         for attr in 'primaryjoin', 'secondaryjoin':
             val = getattr(self, attr)
             if val is not None:
-                util.assert_arg_type(val, sql.ColumnElement, attr)
-                setattr(self, attr, _orm_deannotate(val))
+                setattr(self, attr, _orm_deannotate(
+                    expression._only_column_elements(val, attr))
+                )
         if self.order_by is not False and self.order_by is not None:
-            self.order_by = [expression._literal_as_column(x) for x in
+            self.order_by = [expression._only_column_elements(x, "order_by") for x in
                              util.to_list(self.order_by)]
         self._user_defined_foreign_keys = \
-            util.column_set(expression._literal_as_column(x) for x in
+            util.column_set(expression._only_column_elements(x, "foreign_keys") for x in
                             util.to_column_set(self._user_defined_foreign_keys))
         self.remote_side = \
-            util.column_set(expression._literal_as_column(x) for x in
+            util.column_set(expression._only_column_elements(x, "remote_side") for x in
                             util.to_column_set(self.remote_side))
         if not self.parent.concrete:
             for inheriting in self.parent.iterate_to_root():
diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py
index a7f5d396a..6f593ab48 100644
--- a/lib/sqlalchemy/sql/expression.py
+++ b/lib/sqlalchemy/sql/expression.py
@@ -1037,12 +1037,12 @@ def _no_literals(element):
     else:
         return element
 
-def _only_column_elements(element):
+def _only_column_elements(element, name):
     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)
+        raise exc.ArgumentError("Column-based expression object expected for argument '%s'; "
+                                "got: '%s', type %s" % (name, element, type(element)))
     return element
     
 def _corresponding_column_or_error(fromclause, column,