- Modify the text of the message which occurs

when the "identity" key isn't detected on
flush, to include the common cause that
the Column isn't set up to detect
auto-increment correctly; [ticket:2170].
Also in 0.6.8.

3 files changed, 18 insertions, 6 deletions

diff --git a/CHANGES b/CHANGES
index 72c8c86a1..505df6394 100644
--- a/CHANGES
+++ b/CHANGES
@@ -18,6 +18,13 @@ CHANGES
     create multiple event listeners for 
     subclasses either.  [ticket:2180]
 
+  - Modify the text of the message which occurs
+    when the "identity" key isn't detected on 
+    flush, to include the common cause that
+    the Column isn't set up to detect
+    auto-increment correctly; [ticket:2170].
+    Also in 0.6.8.
+
 - sql
   - Fixed bug whereby metadata.reflect(bind)
     would close a Connection passed as a
diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index 8f8770a3b..29353c4b7 100644
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -1085,10 +1085,15 @@ class Session(object):
             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 occurring at an '
-                        'inappropriate time, such as during a load '
-                        'operation.' % mapperutil.state_str(state))
+                raise exc.FlushError(
+                    "Instance %s has a NULL identity key.  If this is an "
+                    "auto-generated value, check that the database table "
+                    "allows generation of new primary key values, and that "
+                    "the mapped Column object is configured to expect these "
+                    "generated values.  Ensure also that this flush() is "
+                    "not occurring at an inappropriate time, such as within "
+                    "a load() event." % mapperutil.state_str(state)
+                )
 
             if state.key is None:
                 state.key = instance_key
diff --git a/test/orm/test_unitofwork.py b/test/orm/test_unitofwork.py
index 8b2787d12..10d13ec8a 100644
--- a/test/orm/test_unitofwork.py
+++ b/test/orm/test_unitofwork.py
@@ -2469,7 +2469,7 @@ class PartialNullPKTest(fixtures.MappedTest):
         assert_raises_message(
             sa.exc.FlushError,
             r"Instance \<T1 at .+?\> has a NULL "
-            "identity key.  Check if this flush is occurring "
-            "at an inappropriate time, such as during a load operation.",
+            "identity key.  If this is an auto-generated value, "
+            "check that the database table allows generation ",
             s.commit
         )