Add "multi-engine" support for Trainwreck transaction views

tailbone/app.py

@@ -30,6 +30,7 @@ import os
 import warnings
 
 import sqlalchemy as sa
+from sqlalchemy.orm import sessionmaker, scoped_session
 
 from rattail.config import make_config
 from rattail.exceptions import ConfigurationError
@@ -37,6 +38,7 @@ from rattail.db.types import GPCType
 
 from pyramid.config import Configurator
 from pyramid.authentication import SessionAuthenticationPolicy
+from zope.sqlalchemy import register
 
 import tailbone.db
 from tailbone.auth import TailboneAuthorizationPolicy
@@ -69,6 +71,13 @@ def make_rattail_config(settings):
     if hasattr(rattail_config, 'tempmon_engine'):
         tailbone.db.TempmonSession.configure(bind=rattail_config.tempmon_engine)
 
+    # create session wrappers for each "extra" Trainwreck engine
+    for key, engine in rattail_config.trainwreck_engines.items():
+        if key != 'default':
+            Session = scoped_session(sessionmaker(bind=engine))
+            register(Session)
+            tailbone.db.ExtraTrainwreckSessions[key] = Session
+
     # Make sure rattail config object uses our scoped session, to avoid
     # unnecessary connections (and pooling limits).
     rattail_config._session_factory = lambda: (tailbone.db.Session(), False)