- Fixed bug where the session attachment error "object is already

attached to session X" would fail to prevent the object from
also being attached to the new session, in the case that execution
continued after the error raise occurred.
fixes #3301

diff --git a/doc/build/changelog/changelog_10.rst b/doc/build/changelog/changelog_10.rst
index b54a43aaea8e82368c920578e7d5e3059b7f0e0f..474cec093917a19900d48f6055bad7fa73159336 100644 (file)
--- a/doc/build/changelog/changelog_10.rst
+++ b/doc/build/changelog/changelog_10.rst
@@ -23,6 +23,15 @@
     series as well.  For changes that are specific to 1.0 with an emphasis
     on compatibility concerns, see :doc:`/changelog/migration_10`.
 
+    .. change::
+        :tags: bug, orm
+        :tickets: 3301
+
+        Fixed bug where the session attachment error "object is already
+        attached to session X" would fail to prevent the object from
+        also being attached to the new session, in the case that execution
+        continued after the error raise occurred.
+
     .. change::
         :tags: bug, ext
         :tickets: 3219, 3240

diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index f02d8b54efe1d7230e44fcaffced3437cfe7f645..bc9444040eeb39f391883dbad629cd9aaac1b1cc 100644 (file)
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -1830,7 +1830,7 @@ class Session(_SessionClassMethods):
                 "function to send this object back to the transient state." %
                 state_str(state)
             )
-        self._before_attach(state)
+        self._before_attach(state, check_identity_map=False)
         self._deleted.pop(state, None)
         if discard_existing:
             self.identity_map.replace(state)
@@ -1910,13 +1910,12 @@ class Session(_SessionClassMethods):
         self._attach(state, include_before=True)
         state._load_pending = True
 
-    def _before_attach(self, state):
+    def _before_attach(self, state, check_identity_map=True):
         if state.session_id != self.hash_key and \
                 self.dispatch.before_attach:
             self.dispatch.before_attach(self, state.obj())
 
-    def _attach(self, state, include_before=False):
-        if state.key and \
+        if check_identity_map and state.key and \
             state.key in self.identity_map and \
                 not self.identity_map.contains_state(state):
             raise sa_exc.InvalidRequestError(
@@ -1932,10 +1931,11 @@ class Session(_SessionClassMethods):
                 "(this is '%s')" % (state_str(state),
                                     state.session_id, self.hash_key))
 
+    def _attach(self, state, include_before=False):
+
         if state.session_id != self.hash_key:
-            if include_before and \
-                    self.dispatch.before_attach:
-                self.dispatch.before_attach(self, state.obj())
+            if include_before:
+                self._before_attach(state)
             state.session_id = self.hash_key
             if state.modified and state._strong_obj is None:
                 state._strong_obj = state.obj()

diff --git a/test/orm/test_session.py b/test/orm/test_session.py
index 2aa0cd3eb942f33b11f905be13c590c5ddface90..58551d763ede152596fb57e3abc92749b583db4b 100644 (file)
--- a/test/orm/test_session.py
+++ b/test/orm/test_session.py
@@ -505,6 +505,25 @@ class SessionStateTest(_fixtures.FixtureTest):
         assert user not in s
         assert s.query(User).count() == 0
 
+    def test_already_attached(self):
+        User = self.classes.User
+        users = self.tables.users
+        mapper(User, users)
+
+        s1 = Session()
+        s2 = Session()
+
+        u1 = User(id=1, name='u1')
+        make_transient_to_detached(u1)  # shorthand for actually persisting it
+        s1.add(u1)
+
+        assert_raises_message(
+            sa.exc.InvalidRequestError,
+            "Object '<User.*?>' is already attached to session",
+            s2.add, u1
+        )
+        assert u1 not in s2
+        assert not s2.identity_map.keys()
 
     @testing.uses_deprecated()
     def test_identity_conflict(self):
@@ -562,7 +581,7 @@ class SessionStateTest(_fixtures.FixtureTest):
         assert u2 is not None and u2 is not u1
         assert u2 in sess
 
-        assert_raises(Exception, lambda: sess.add(u1))
+        assert_raises(AssertionError, lambda: sess.add(u1))
 
         sess.expunge(u2)
         assert u2 not in sess