Warn for runid changing in load events; add restore_load_context flag

Added a new flag :paramref:`.InstanceEvents.restore_load_context` and
:paramref:`.SessionEvents.restore_load_context` which apply to the
:meth:`.InstanceEvents.load`, :meth:`.InstanceEvents.refresh`, and
:meth:`.SessionEvents.loaded_as_persistent` events, which when set will
restore the "load context" of the object after the event hook has been
called.  This ensures that the object remains within the "loader context"
of the load operation that is already ongoing, rather than the object being
transferred to a new load context due to refresh operations which may have
occurred in the event. A warning is now emitted when this condition occurs,
which recommends use of the flag to resolve this case.  The flag is
"opt-in" so that there is no risk introduced to existing applications.

The change additionally adds support for the ``raw=True`` flag to
session lifecycle events.

Fixes: #5129
Change-Id: I2912f48ac8c5636297d63ed383454930e8e9a6a3

1 files changed, 8 insertions, 8 deletions

diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index fe0640a47..9342c3145 100644
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -1975,7 +1975,7 @@ class Session(_SessionClassMethods):
 
         if pending_to_persistent is not None:
             for state in states.intersection(self._new):
-                pending_to_persistent(self, state.obj())
+                pending_to_persistent(self, state)
 
         # remove from new last, might be the last strong ref
         for state in set(states).intersection(self._new):
@@ -1998,7 +1998,7 @@ class Session(_SessionClassMethods):
             if persistent_to_deleted is not None:
                 # get a strong reference before we pop out of
                 # self._deleted
-                obj = state.obj()
+                obj = state.obj()  # noqa
 
             self.identity_map.safe_discard(state)
             self._deleted.pop(state, None)
@@ -2007,7 +2007,7 @@ class Session(_SessionClassMethods):
             # is still in the transaction snapshot and needs to be
             # tracked as part of that
             if persistent_to_deleted is not None:
-                persistent_to_deleted(self, obj)
+                persistent_to_deleted(self, state)
 
     def add(self, instance, _warn=True):
         """Place an object in the ``Session``.
@@ -2384,7 +2384,7 @@ class Session(_SessionClassMethods):
         if to_attach:
             self._after_attach(state, obj)
         elif revert_deletion:
-            self.dispatch.deleted_to_persistent(self, obj)
+            self.dispatch.deleted_to_persistent(self, state)
 
     def _save_or_update_impl(self, state):
         if state.key is None:
@@ -2466,7 +2466,7 @@ class Session(_SessionClassMethods):
                 % (state_str(state), state.session_id, self.hash_key)
             )
 
-        self.dispatch.before_attach(self, obj)
+        self.dispatch.before_attach(self, state)
 
         return True
 
@@ -2474,12 +2474,12 @@ class Session(_SessionClassMethods):
         state.session_id = self.hash_key
         if state.modified and state._strong_obj is None:
             state._strong_obj = obj
-        self.dispatch.after_attach(self, obj)
+        self.dispatch.after_attach(self, state)
 
         if state.key:
-            self.dispatch.detached_to_persistent(self, obj)
+            self.dispatch.detached_to_persistent(self, state)
         else:
-            self.dispatch.transient_to_pending(self, obj)
+            self.dispatch.transient_to_pending(self, state)
 
     def __contains__(self, instance):
         """Return True if the instance is associated with this session.