#!/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.

"""This module contains the Answer Model"""

__authors__ = [

  '"Todd Larsen" <tlarsen@google.com>',

  '"Sverre Rabbelier" <sverre@rabbelier.nl>',

]

from google.appengine.ext import db

import soc.models.question

import soc.models.quiz

import soc.models.response

from soc.models import base

class Answer(base.ModelWithFieldAttributes):

  """Model of a specific Answer to a Question in a specific Response.

  The properties in this Model do not have verbose_name or help_text,

  because the dynamic nature of the forms required to create, edit, and

  use entities of this Model make them pretty useless.

  """

  #: A required many:1 relationship, where each of many Answers is

  #: a specific answer to a single Question.  An Answer must always

  #: be associated with a Question in order to be interpreted.

  #: It is currently unclear how useful this back-reference will be,

  #: since the same Question could be used in multiple different

  #: Quizzes. Given this, 'answers' currently only exists for

  #: completeness.

  question = db.ReferenceProperty(

    reference_class=soc.models.question.Question, required=True,

    collection_name="answers")

  #: A many:1 relationship, where each of many Answers to different

  #: Questions represents the answer set of a specific Response to a Quiz.

  #: The back-reference in the Response model is a Query named 'answers'

  #: which represents all of the specific Answers to Questions in that

  #: Response.

  #:

  #: One and only one of the response or quiz ReferenceProperties *must*

  #: be defined for an Answer entity.

  response = db.ReferenceProperty(

      reference_class=soc.models.response.Response, required=False,

      collection_name="answers")

  #: A many:1 relationship, where each of many Answers to different

  #: Questions represents the solution set for the Questions in a Quiz.

  #: The back-reference in the Quiz model is a Query named 'solutions'

  #: which represents all of the solutions to Questions in that Quiz.

  #:

  #: One and only one of the response or quiz ReferenceProperties *must*

  #: be defined for an Answer entity.

  quiz = db.ReferenceProperty(

      reference_class=soc.models.quiz.Quiz, required=False,

      collection_name="solutions")

  #: db.ListProperty of strings representing the answer value or values.

  #:

  #: For Questions that are not multiple-choice (see the choice_ids and

  #: choices properties of soc.models.question.Question), this list will

  #: contain a single string that is a free-form text answer.

  #:

  #: For Questions that *are* multiple-choice, this list will contain one

  #: or more short, plain-text, "link_id-like" strings representing the

  #: "encoded" answer choices (see the choice_ids property in

  #: soc.models.question.Question).  For such multiple-choice Questions,    

  #: how many strings are stored depends on the max_answers property of

  #: the soc.models.question.Question entity for which this is an Answer.

  #:

  #: If question.is_optional is True, 'answers' may even be None or an

  #: empty list if no answers were provided.

  #:

  #: Answers can be indexed, filtered, and sorted by this list, but only in

  #: the way that query operators work with a db.ListProperty.

  answers = db.ListProperty(item_type=str)