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gnuviechadmin-historic/gnuviechadmin/backend/BackendEntityHandler.py

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# -*- coding: utf-8 -*-
#
# Copyright (C) 2007, 2008 by Jan Dittberner.
#
# This program 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 2 of the License, or
# (at your option) any later version.
#
# This program 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 this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
# USA.
#
# Version: $Id$
"""This module defines the BackendEntityHandler class."""
import logging
from sqlalchemy.orm import create_session
class BackendEntityHandler(object):
"""This class is a handler for BackendEntity instances."""
def __init__(self, entityclass, toclass, verbose = False):
"""Initialize the handler with a specific entity class,
transfer object class and verbosity flag."""
self.logger = logging.getLogger("%s.%s" % (
self.__class__.__module__, self.__class__.__name__))
self.entityclass = entityclass
self.toclass = toclass
self.verbose = verbose
def create(self, **kwargs):
"""Create a new entity of the managed type with the fields set
to the values in kwargs."""
self.logger.debug("create with params %s", str(kwargs))
sess = create_session()
transaction = sess.create_transaction()
delegate = self.toclass(**kwargs)
entity = self.entityclass(delegate, self.verbose)
try:
sess.save(delegate)
sess.flush()
sess.refresh(delegate)
entity.create_hook(sess)
sess.flush()
transaction.commit()
except:
transaction.rollback()
self.logger.exception("Exception in create.")
raise
def fetchall(self, **kwargs):
"""Fetches all entities of the managed entity type."""
self.logger.debug("fetchall with params %s", str(kwargs))
session = create_session()
query = session.query(self.toclass)
if kwargs:
allentities = query.filter_by(**kwargs).all()
else:
allentities = query.all()
return [self.entityclass(entity, self.verbose) \
for entity in allentities]
def delete(self, pkvalue):
"""Deletes the entity of the managed entity type that has the
specified primary key value."""
self.logger.debug("delete with primary key %s", str(pkvalue))
sess = create_session()
transaction = sess.create_transaction()
try:
tobj = sess.query(self.toclass).get(pkvalue)
if tobj:
entity = self.entityclass(tobj, self.verbose)
self.logger.info("delete %s", str(entity))
if self.verbose:
print "delete %s" % (str(entity))
entity.delete_hook(sess)
sess.delete(tobj)
sess.flush()
transaction.commit()
except Exception:
transaction.rollback()
self.logger.exception("Exception in delete.")
raise