app/melange/appengine/db.py

# 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.

"""App Engine datastore related functions and classes."""

from django.core import validators

from google.appengine.ext import ndb


def email_validator(property, value):
  """Validates whether the input value for the specified property
  is a valid email address.

  The function signature is required by NBD API. Property parameter is not
  actually used in this function.

  Args:
    property: validated model property
    value: value to validate

  Raises:
    ValueError: if the specified value is not a valid email address.
  """
  try:
    # use internal django's validator
    validators.validate_email(value)
  except Exception:
    raise ValueError('%s is not a valid email address.' % value)


_LINK_VALIDATOR = validators.URLValidator()
def link_validator(property, value):
  """Validates whether the input value for the specified property
  is a valid URL.

  The function signature is required by NBD API. Property parameter is not
  actually used in this function.

  Args:
    property: validated model property
    value: value to validate

  Raises:
    ValueError: if the specified value is not a valid URL.
  """
  try:
    # use internal django's validator
    _LINK_VALIDATOR(value)
  except Exception:
    raise ValueError('%s is not a valid URL.' % value)


def addFilterToQuery(query, prop, values):
  """Extends the specified query by adding a filter on the specified property
  with the specified value.

  Args:
    query: query object to extend.
    prop: property of the query model on which to add a filter.
    values: sequence of values to compare with the property value.
  """
  if len(values) == 1:
    query.filter(prop.name, values[0])
  else:
    query.filter('%s IN' % prop.name, values)


def addFilterToNDBQuery(query, prop, values):
  """Extends the specified query by adding a filter on the specified property
  with the specified value.

  Args:
    query: query object to extend.
    prop: property of the query model on which to add a filter.
    values: sequence of values to compare with the property value.
  """
  if len(values) == 1:
    return query.filter(prop == values[0])
  else:
    return query.filter(prop.IN(values))


def toDict(entity, exclude_computed=None):
  """Returns a dict with values of a datastore entity.

  Args:
    entity: Datastore entity.
    exclude_computed: If set to True, computed properties are not included.
      in the result.

  Returns:
    A dict mapping properties to the corresponding values.

  Raises:
    TypeError: if the specified entity is not App Engine datastore entity.
  """
  if not exclude_computed:
    return entity.to_dict()
  else:
    values = {}
    for prop_name, prop_type in entity._properties.iteritems():
      if type(prop_type) != ndb.ComputedProperty:
        values[prop_name] = getattr(entity, prop_name)
    return values