Add utility function, get_last_card_number()

corepos/db/util.py

@@ -0,0 +1,40 @@
+# -*- coding: utf-8; -*-
+################################################################################
+#
+#  pyCOREPOS -- Python Interface to CORE POS
+#  Copyright © 2018-2019 Lance Edgar
+#
+#  This file is part of pyCOREPOS.
+#
+#  pyCOREPOS is free software: you can redistribute it and/or modify it under
+#  the terms of the GNU General Public License as published by the Free
+#  Software Foundation, either version 3 of the License, or (at your option)
+#  any later version.
+#
+#  pyCOREPOS is distributed in the hope that it will be useful, but WITHOUT ANY
+#  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+#  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+#  details.
+#
+#  You should have received a copy of the GNU General Public License along with
+#  pyCOREPOS.  If not, see <http://www.gnu.org/licenses/>.
+#
+################################################################################
+"""
+CORE POS Database Utilities
+"""
+
+from __future__ import unicode_literals, absolute_import
+
+import sqlalchemy as sa
+
+from corepos.db import model as corepos
+
+
+def get_last_card_number(session):
+    """
+    Convenience function, to return the "last" (max) value for the
+    ``custdata.CardNo`` field, for use when generating new values.
+    """
+    return session.query(sa.func.max(corepos.Customer.card_number))\
+                  .scalar() or 0