- collection docs

- Added an assertion during flush which ensures
that no NULL-holding identity keys were generated
on "newly persistent" objects.
This can occur when user defined code inadvertently
triggers flushes on not-fully-loaded objects.

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index d906df2a3..54b41fcc6 100644
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -1018,6 +1018,14 @@ class Session(object):
         if obj is not None:
 
             instance_key = mapper._identity_key_from_state(state)
+            
+            if _none_set.issubset(instance_key[1]) and \
+                not mapper.allow_partial_pks or \
+                _none_set.issuperset(instance_key[1]):
+                raise exc.FlushError('Instance %s has a NULL identity '
+                        'key.  Check if this flush is occuring at an '
+                        'inappropriate time, such as during a load '
+                        'operation.' % mapperutil.state_str(state))
 
             if state.key is None:
                 state.key = instance_key