conv_dict_to_update.py

def convert_dict_to_update(dictionary, roots=None, return_dict=None):
    """
      Returns a new dict that can be used in Document.update(**dict),
      this is used for updating MongoEngine documents with dictionary
      serialized from json.

      >>> data = {'email' : 'email@example.com'}
      >>> convert_dict_to_update(data)
      {'set__email': 'email@example.com'}

      :param dictionary: dictionary with update parameters
      :param roots: roots of nested documents - used for recursion
      :param return_dict: used for recursion

      :return: new dict
    """
    if return_dict is None:
        return_dict = {}
    if roots is None:
        roots = []

    for key, value in dictionary.iteritems():
        if isinstance(value, dict):
            roots.append(key)
            convert_dict_to_update(value, roots=roots, return_dict=return_dict)
            roots.remove(key)  # go one level down in the recursion
        else:
            if roots:
                set_key_name = 'set__{roots}__{key}'.format(
                    roots='__'.join(roots), key=key)
            else:   
                set_key_name = 'set__{key}'.format(key=key)
            return_dict[set_key_name] = value

    return return_dict