#!/usr/bin/python2.5

#

# Copyright 2008 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.

"""Helpers functions for updating different kinds of models in datastore.

"""

__authors__ = [

  '"Pawel Solyga" <pawel.solyga@gmail.com>',

  ]

from google.appengine.ext import db

def updateModelProperties(model, **model_properties):

  """Update existing model entity using supplied model properties.

  Args:

    model: a model entity

    **model_properties: keyword arguments that correspond to model entity

      properties and their values

  Returns:

    the original model entity with any supplied properties changed 

  """

  def update():

    return _unsafeUpdateModelProperties(model, **model_properties)

  return db.run_in_transaction(update)

def _unsafeUpdateModelProperties(model, **model_properties):

  """(see updateModelProperties)

  Like updateModelProperties(), but not run within a transaction. 

  """

  properties = model.properties()

  for prop in properties.values():

    if prop.name in model_properties:

      value = model_properties[prop.name]

      prop.__set__(model, value)

  model.put()

  return model