appengine/standard/multitenancy/datastore.py

# Copyright 2015 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""
Sample App Engine application demonstrating how to use the Namespace Manager
API with Datastore.

For more information, see README.md.
"""

# [START gae_multitenancy_datastore]
from google.appengine.api import namespace_manager
from google.appengine.ext import ndb
import webapp2


class Counter(ndb.Model):
    count = ndb.IntegerProperty()


@ndb.transactional
def update_counter(name):
    """Increment the named counter by 1."""
    counter = Counter.get_by_id(name)
    if counter is None:
        counter = Counter(id=name, count=0)

    counter.count += 1
    counter.put()

    return counter.count


class DatastoreCounterHandler(webapp2.RequestHandler):
    """Increments counters in the global namespace as well as in whichever
    namespace is specified by the request, which is arbitrarily named 'default'
    if not specified."""

    def get(self, namespace="default"):
        global_count = update_counter("counter")

        # Save the current namespace.
        previous_namespace = namespace_manager.get_namespace()
        try:
            namespace_manager.set_namespace(namespace)
            namespace_count = update_counter("counter")
        finally:
            # Restore the saved namespace.
            namespace_manager.set_namespace(previous_namespace)

        self.response.write(
            "Global: {}, Namespace {}: {}".format(
                global_count, namespace, namespace_count
            )
        )


app = webapp2.WSGIApplication(
    [
        (r"/datastore", DatastoreCounterHandler),
        (r"/datastore/(.*)", DatastoreCounterHandler),
    ],
    debug=True,
)
# [END gae_multitenancy_datastore]