chrome/common/extensions/docs/server2/datastore_models.py

   1 # Copyright 2013 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 import cPickle
   6 import traceback
   7
   8 from appengine_wrappers import db
   9
  10 # A collection of the data store models used throughout the server.
  11 # These values are global within datastore.
  12
  13 class PersistentObjectStoreItem(db.Model):
  14   pickled_value = db.BlobProperty()
  15
  16   @classmethod
  17   def CreateKey(cls, namespace, key):
  18     path = '%s/%s' % (namespace, key)
  19     try:
  20       return db.Key.from_path(cls.__name__, path)
  21     except Exception:
  22       # Probably AppEngine's BadValueError for the name being too long, but
  23       # it's not documented which errors can actually be thrown here, so catch
  24       # 'em all.
  25       raise ValueError(
  26           'Exception thrown when trying to create db.Key from path %s: %s' % (
  27               path, traceback.format_exc()))
  28
  29   @classmethod
  30   def CreateItem(cls, namespace, key, value):
  31     return PersistentObjectStoreItem(key=cls.CreateKey(namespace, key),
  32                                      pickled_value=cPickle.dumps(value))
  33
  34   def GetValue(self):
  35     return cPickle.loads(self.pickled_value)