handle the case where we want to delete/insert on PK, disable row switch

3 files changed, 23 insertions, 12 deletions

diff --git a/lib/sqlalchemy/orm/dependency.py b/lib/sqlalchemy/orm/dependency.py
index 12676faca..9f1e497af 100644
--- a/lib/sqlalchemy/orm/dependency.py
+++ b/lib/sqlalchemy/orm/dependency.py
@@ -1215,6 +1215,16 @@ class DeleteBeforeInsertDP(object):
             (before_delete, deletes)
         ])
 
+    @classmethod
+    def save_depends_on_delete(cls, uow, dependent, dependee, mapper):
+        """return True if we've set up a dependency rule between two
+        states.
+
+        """
+        dep_proc = unitofwork.SaveUpdateState(uow, dependent, mapper)
+        dee_proc = unitofwork.DeleteState(uow, dependee, mapper)
+        return (dee_proc, dep_proc) in uow.dependencies
+
     def per_state_flush_actions(self, uow, states, isdelete):
         # finally, we get called when the UOW has decided, "OK,
         # we need to figure out on a state-by-state basis which of you
diff --git a/lib/sqlalchemy/orm/persistence.py b/lib/sqlalchemy/orm/persistence.py
index 44da88118..1f5507edf 100644
--- a/lib/sqlalchemy/orm/persistence.py
+++ b/lib/sqlalchemy/orm/persistence.py
@@ -119,8 +119,8 @@ def delete_obj(base_mapper, states, uowtransaction):
                         in states_to_delete:
         mapper.dispatch.after_delete(mapper, connection, state)
 
-
-def _organize_states_for_save(base_mapper, states, uowtransaction):
+@util.dependencies("sqlalchemy.orm.dependency")
+def _organize_states_for_save(dependency, base_mapper, states, uowtransaction):
     """Make an initial pass across a set of states for INSERT or
     UPDATE.
 
@@ -168,16 +168,16 @@ def _organize_states_for_save(base_mapper, states, uowtransaction):
                     "with persistent instance %s" %
                     (state_str(state), instance_key,
                      state_str(existing)))
-
-            base_mapper._log_debug(
-                "detected row switch for identity %s.  "
-                "will update %s, remove %s from "
-                "transaction", instance_key,
-                state_str(state), state_str(existing))
-
-            # remove the "delete" flag from the existing element
-            uowtransaction.remove_state_actions(existing)
-            row_switch = existing
+            elif not dependency.DeleteBeforeInsertDP.save_depends_on_delete(uowtransaction, state, existing, mapper):
+                base_mapper._log_debug(
+                    "detected row switch for identity %s.  "
+                    "will update %s, remove %s from "
+                    "transaction", instance_key,
+                    state_str(state), state_str(existing))
+
+                # remove the "delete" flag from the existing element
+                uowtransaction.remove_state_actions(existing)
+                row_switch = existing
 
         if not has_identity and not row_switch:
             states_to_insert.append(
diff --git a/lib/sqlalchemy/orm/unitofwork.py b/lib/sqlalchemy/orm/unitofwork.py
index f2a419733..1e8d3e4dc 100644
--- a/lib/sqlalchemy/orm/unitofwork.py
+++ b/lib/sqlalchemy/orm/unitofwork.py
@@ -160,6 +160,7 @@ class UOWTransaction(object):
 
         return state in self.states and self.states[state][0]
 
+
     def memo(self, key, callable_):
         if key in self.attributes:
             return self.attributes[key]