Override the CORE-API -> Rattail Demo importer for Store data

this lets the demo have random extra Store records and the importer will just
ignore them

rattail_demo/config.py

@@ -26,3 +26,4 @@ class DemoConfigExtension(ConfigExtension):
 
         # default import handlers
         config.setdefault('rattail.importing', 'versions.handler', 'rattail_demo.importing.versions:FromRattailDemoToRattailDemoVersions')
+        config.setdefault('rattail.importing', 'corepos_api.handler', 'rattail_demo.importing.corepos_api:FromCOREPOSToRattail')

rattail_demo/emails.py

@@ -1,10 +1,8 @@
-# -*- coding: utf-8 -*-
+# -*- coding: utf-8; -*-
 """
 Email definitions
 """
 
-from __future__ import unicode_literals, absolute_import
-
 
 # bring in some common config from rattail
 from rattail.emails import (upgrade_failure,
@@ -19,3 +17,7 @@ from rattail_tempmon.emails import (tempmon_critical_high_temp,
                                     tempmon_critical_low_temp,
                                     tempmon_error,
                                     tempmon_client_offline)
+
+# common config from rattail-corepos
+from rattail_corepos.emails import (rattail_import_corepos_api_updates,
+                                    rattail_import_corepos_db_updates)

rattail_demo/importing/corepos_api.py

@@ -0,0 +1,31 @@
+# -*- coding: utf-8; -*-
+"""
+CORE-POS API -> Rattail Demo importing
+"""
+
+from rattail_corepos.importing.corepos import api as base
+
+
+class FromCOREPOSToRattail(base.FromCOREPOSToRattail):
+    """
+    Override some parts of CORE-POS API -> Rattail importing.
+    """
+
+    def get_importers(self):
+        importers = super(FromCOREPOSToRattail, self).get_importers()
+        importers['Store'] = StoreImporter
+        return importers
+
+
+class StoreImporter(base.StoreImporter):
+    """
+    Tweak how we import Store data from CORE-POS API.
+    """
+
+    def cache_query(self):
+        model = self.model
+        # we ignore any Store records which are not associated with CORE, so
+        # the importer will never be tempted to delete them etc.
+        return self.session.query(model.Store)\
+                           .join(model.CoreStore)\
+                           .filter(model.CoreStore.corepos_id != None)