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)

tailbone/db.py

@@ -41,6 +41,9 @@ Session = scoped_session(sessionmaker(class_=SessionBase, rattail_config=None, r
 TempmonSession = scoped_session(sessionmaker())
 TrainwreckSession = scoped_session(sessionmaker())
 
+# empty dict for now, this must populated on app startup (if needed)
+ExtraTrainwreckSessions = {}
+
 
 class TailboneSessionDataManager(datamanager.SessionDataManager):
     """Integrate a top level sqlalchemy session transaction into a zope transaction

tailbone/views/master.py

@@ -130,6 +130,8 @@ class MasterView(View):
     # other things also, to get a DB picker in the header for all views
     supports_multiple_engines = False
     engine_type_key = 'rattail'
+    SessionDefault = None
+    SessionExtras = {}
 
     row_attrs = {}
     cell_attrs = {}
@@ -172,9 +174,16 @@ class MasterView(View):
     @property
     def Session(self):
         """
-        SQLAlchemy scoped session to use when querying the database.  Defaults
+        Which session we return may depend on user's "current" engine.
-        to ``tailbone.db.Session``.
         """
+        if self.supports_multiple_engines:
+            dbkey = self.get_current_engine_dbkey()
+            if dbkey != 'default' and dbkey in self.SessionExtras:
+                return self.SessionExtras[dbkey]
+
+        if self.SessionDefault:
+            return self.SessionDefault
+
         from tailbone.db import Session
         return Session
 

tailbone/views/trainwreck.py

@@ -2,7 +2,7 @@
 ################################################################################
 #
 #  Rattail -- Retail Software Framework
-#  Copyright © 2010-2017 Lance Edgar
+#  Copyright © 2010-2019 Lance Edgar
 #
 #  This file is part of Rattail.
 #
@@ -29,8 +29,9 @@ from __future__ import unicode_literals, absolute_import
 import six
 
 from rattail.time import localtime
+from rattail.util import OrderedDict
 
-from tailbone.db import TrainwreckSession
+from tailbone.db import TrainwreckSession, ExtraTrainwreckSessions
 from tailbone.views import MasterView
 
 
@@ -38,7 +39,6 @@ class TransactionView(MasterView):
     """
     Master view for Trainwreck transactions
     """
-    Session = TrainwreckSession
     # model_class = trainwreck.Transaction
     model_title = "Trainwreck Transaction"
     model_title_plural = "Trainwreck Transactions"
@@ -48,6 +48,11 @@ class TransactionView(MasterView):
     editable = False
     deletable = False
 
+    supports_multiple_engines = True
+    engine_type_key = 'trainwreck'
+    SessionDefault = TrainwreckSession
+    SessionExtras = ExtraTrainwreckSessions
+
     labels = {
         'cashback': "Cash Back",
     }
@@ -125,6 +130,15 @@ class TransactionView(MasterView):
         'void',
     ]
 
+    def get_db_engines(self):
+        engines = OrderedDict()
+        if self.rattail_config.trainwreck_engine:
+            engines['default'] = self.rattail_config.trainwreck_engine
+        for dbkey in sorted(self.rattail_config.trainwreck_engines):
+            if dbkey != 'default':
+                engines[dbkey] = self.rattail_config.trainwreck_engines[dbkey]
+        return engines
+
     def configure_grid(self, g):
         super(TransactionView, self).configure_grid(g)
         g.filters['receipt_number'].default_active = True