app/soc/mapreduce/model_pacifier.py

# Copyright 2013 the Melange authors.
#
# 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.

"""MapReduce that removes all entities of the model which is specified
as its parameter.

Be aware that these scripts delete all the data belonging to a model. It
may be impossible to restore that data, so please use this module with
extreme caution after you have consulted the development mailing list.
"""

from google.appengine.ext import ndb

from mapreduce import operation


def process(entity):
  """Processes the entity by deleting it.

  Args:
    entity: the specified entity
  """
  yield operation.db.Delete(entity)
  yield operation.counters.Increment('entity_deleted')


@ndb.transactional
def _deleteEntityTxn(entity_key):
  """Deletes the specified entity in a transaction.

  Args:
    entity: Entity's key.
  """
  ndb.Key.from_old_key(entity_key).delete()


def processNDB(entity_key):
  """Processes the entity by deleting it.

  Args:
    entity: the specified entity
  """
  _deleteEntityTxn(entity_key)
  yield operation.counters.Increment('entity_deleted')