pycorepos/corepos/db/util.py

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# -*- coding: utf-8; -*-
################################################################################
#
# pyCOREPOS -- Python Interface to CORE POS
# Copyright © 2018-2020 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
"""
import sqlalchemy as sa
from corepos.db.office_op 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
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def table_exists(session, model_class):
"""
Determine if a table exists in the database.
:param session: SQLAlchemy session object, opened against the database in
question.
:param model_class: The model class associated with the table in question.
:returns: Boolean indicating if the table exists.
"""
try:
session.query(model_class).count()
except sa.exc.ProgrammingError as error:
if "doesn't exist" in str(error):
return False
else:
raise
else:
return True