Question

I’ve just started using Tastypie and am trying to work out how to format the output as I would like (I’m only interested in GET methods).
I have a quiz object which may have multiple questions, each question may be in multiple quizzes (hence the many to many, rather than one to many) – but when someone requests the quiz object via the API, I only want to return a (json) array of the questions, I don’t want/need to display the intermediate relationship table data.

Some code:

Models.py:

class Question(models.Model):
    owner = models.ForeignKey(User)
    created_date = models.DateTimeField('date created',default=datetime.now)
    lastupdated_date = models.DateTimeField('date updated',default=datetime.now)
    title = models.CharField(max_length=500)   
    def __unicode__(self):
        return self.title

class Quiz(models.Model):
    owner = models.ForeignKey(User)
    created_date = models.DateTimeField('date created',default=datetime.now)
    lastupdated_date = models.DateTimeField('date updated',default=datetime.now)
    title = models.CharField(max_length=200)
    description = models.TextField(blank=True)
    props = models.TextField(blank=True)
    questions = models.ManyToManyField(Question, through='QuizQuestion')

    def __unicode__(self):
        return self.title


class QuizQuestion(models.Model):
    quiz = models.ForeignKey(Quiz)
    question = models.ForeignKey(Question)
    order = models.IntegerField(default=1)

and resources.py:

class QuizResource(ModelResource):
    q = fields.ToManyField('mquiz.api.resources.QuizQuestionResource', 'quizquestion_set', related_name='quiz', full=True)
    class Meta:
        queryset = Quiz.objects.all()
        allowed_methods = ['get']
        fields = ['title', 'id']
        resource_name = 'quiz'
        include_resource_uri = False

class QuizQuestionResource(ModelResource):
    question = fields.ToOneField('mquiz.api.resources.QuestionResource', 'question', full=True)
    class Meta:
        queryset = QuizQuestion.objects.all()
        allowed_methods = ['get']
        include_resource_uri = False

class QuestionResource(ModelResource): 
    class Meta:
        queryset = Question.objects.all()
        allowed_methods = ['get']
        fields = ['title']
        resource_name = 'question'
        include_resource_uri = False

This functions well enough, but doesn’t quite give the output I’d like. It gives me the output:

{
  "id": "1",
  "q": [
    {
      "id": "1",
      "order": 1,
      "question": {
        "title": "What is the capital of Latvia?"
      }
    },
    {
      "id": "2",
      "order": 2,
      "question": {
        "title": "What is the capital of Ethiopia?"
      }
    }
  ],
  "title": "Capitals"
}

However, what I would really like is the output in this format, since I don’t need to have all the intermediate table id/order fields showing:

{
  "id": "1",
  "q": [
    {
        "title": "What is the capital of Latvia?"
    },
    {
        "title": "What is the capital of Ethiopia?"
    }
  ],
  "title": "Capitals"
}

Is there a way to achieve this? Any help/pointers much appreciated.

UPDATE:
Using a custom serialiser like this seems to work:

class QuizJSONSerializer(Serializer):
    json_indent = 2

    def to_json(self, data, options=None):
        options = options or {}
        data = self.to_simple(data, options)
        for question in data['q']:
            del question['id']
            del question['order']
            for qkey, qvalue in question['question'].items():
                question[qkey] = qvalue
            del question['question']
        return simplejson.dumps(data, cls=json.DjangoJSONEncoder,
                sort_keys=True, ensure_ascii=False, indent=self.json_indent)

Sure there may be more generic way to code this – but works for now.

Answer 1

Overriding the serialize function of the resource object with your own code would be a good approach, but refactoring the data bundle within the dehydrate method would be a quick fix