Use existing session where possible

uber/api.py

@@ -778,7 +778,7 @@ def create(self, first_name, last_name, email, params):
         Example `params` dictionary for setting extra parameters:
         <pre>{"placeholder": "yes", "legal_name": "First Last", "cellphone": "5555555555"}</pre>
         """
-        with Session() as session:
+        with Session(create_savepoint=True) as session:
             attendee_query = session.query(Attendee).filter(Attendee.first_name.ilike(first_name),
                                                             Attendee.last_name.ilike(last_name),
                                                             Attendee.email.ilike(email))
@@ -820,7 +820,7 @@ def update(self, id, params):
         Example:
         <pre>{"first_name": "First", "paid": "doesn't need to", "ribbon": "Volunteer, Panelist"}</pre>
         """
-        with Session() as session:
+        with Session(create_savepoint=True) as session:
             attendee = session.attendee(id, allow_invalid=True)
 
             if not attendee:

uber/models/__init__.py

@@ -2376,11 +2376,38 @@ def __getattr__(self, name):
         """
         return getattr(_ScopedSession, name)
 
-    def __call__(self, *args, **kwargs):
+    def __call__(self, create_savepoint=False, *args, **kwargs):
         """
-        Create isolated session, to match old behavior on 'with Session() as session'
+        Creates a new session or returns the current session.
+
+        create_savepoint (bool): Flush the current session to the DB and create a savepoint.
+                                 This lets you use session.rollback() to undo only changes made after the savepoint.
+                                 This is ignored if we're returning a new session.
         """
-        return SessionFactory(*args, **kwargs)
+        try:
+            req = cherrypy.request
+
+            if 'bind' not in kwargs:
+                if not hasattr(req, 'db_connection'):
+                    req.db_connection = engine.connect()
+
+                    def release_connection():
+                        req.db_connection.close()
+                    req.hooks.attach('on_end_request', release_connection)
+
+                kwargs['bind'] = req.db_connection
+
+            session = SessionFactory(*args, **kwargs)
+
+            if create_savepoint and kwargs.get('bind') == getattr(req, 'db_connection', None) and req.db_connection.in_transaction():
+                session.begin_nested()
+
+            return session
+
+        except AttributeError:
+            # We are outside of a web request (e.g., Celery workers, cron jobs, test scripts)
+            # Fall back to standard unmanaged behavior.
+            return SessionFactory(*args, **kwargs)
 
 Session = HybridSessionProxy()
 

uber/site_sections/promo_codes.py

@@ -36,9 +36,8 @@ def add_promo_code_words(self, session, text='', part_of_speech=0):
         text = text.strip()
         words = []
         if text:
-            with Session() as session:
-                old_words = set(s for (s,) in session.query(PromoCodeWord.normalized_word).filter(
-                    PromoCodeWord.part_of_speech == part_of_speech).all())
+            old_words = set(s for (s,) in session.query(PromoCodeWord.normalized_word).filter(
+                PromoCodeWord.part_of_speech == part_of_speech).all())
 
             for word in [s for s in shlex.split(text.replace(',', ' ')) if s]:
                 if PromoCodeWord.normalize_word(word) not in old_words:

uber/utils.py

@@ -2109,7 +2109,7 @@ def attendee_import(import_job):
         from uber.models import Attendee, AttendeeAccount, DeptMembership, DeptRole
         from functools import partial
 
-        with uber.models.Session() as session:
+        with uber.models.Session(create_savepoint=True) as session:
             service, message, target_url = get_api_service_from_server(import_job.target_server,
                                                                        import_job.api_token)