When posting to my Django API : errorcom.google.gson.JsonParseException: unable to parse json

Question

Can someone tell me what I am doing wrong in this post?

I suspect I am posting to my django API incorrectly. I have basically a Question object that has a field for an array of Answers. I can post correctly without the answers, but when I try to add the JsonArray for answers the post fails with the unable to parse error.

LogCat Excerpt

05-21 00:12:52.875  15720-15720/com.pipit.waffle D/ConnectToBackend﹕ {"text":"gf or ed","answers":[{"text":"gf","votes":0,"id":null},{"text":"ed","votes":0,"id":null}],"user_id":"temp user id"}
05-21 00:12:52.875  15720-15720/com.pipit.waffle D/ConnectToBackend﹕ postQuestion called with {MY API} and has errorcom.google.gson.JsonParseException: unable to parse json
05-21 00:12:52.875  15720-15720/com.pipit.waffle D/ConnectToBackend﹕ postQuestion returns result with NULL

Django Side

serializers.py

class EmbeddedAnswerSerializer(serializers.ModelSerializer):
    votes = serializers.IntegerField(read_only=True)
    picture = serializers.ImageField(read_only=True)
    class Meta:
        model = Answer
        fields = ('id', 'picture', 'text', 'votes',)


class QuestionSerializer(serializers.ModelSerializer):
    answers = EmbeddedAnswerSerializer(many=True, source='answer_set')

    class Meta:
        model = Question
        fields = ('id', 'answers', 'created_at', 'text', 'user_id',)


class AnswerSerializer(serializers.ModelSerializer):
    text = serializers.CharField(read_only=True)
    vote = serializers.BooleanField(required=True)
    picture = serializers.ImageField(read_only=True)
    votes = serializers.IntegerField(read_only=True)

models.py

class Question(models.Model):
    user_id = models.CharField(max_length=36)
    text = models.CharField(max_length=140)
    created_at = models.DateTimeField(auto_now_add=True)

    def __unicode__(self):
        return u'Question #{}'.format(self.pk)

class Answer(models.Model):
    picture = models.ImageField(("Picture"), upload_to=upload_pic_to, blank=True)
    question = models.ForeignKey(Question)
    text = models.CharField(max_length=25)
    votes = models.IntegerField(default=0)

    def __unicode__(self):
        return u'Answer to question {} ({} votes)'.format(self.question_id, self.votes)

Client Side (android)

public static void postQuestion(final Context mcontext, Question mquestion){
        JsonArray answerarray = new JsonArray();
        JsonObject answerjson = new JsonObject();
        JsonObject answerjson2 = new JsonObject();
        answerjson.addProperty("text", mquestion.getChoices().get(0).getAnswerBody());
        answerjson2.addProperty("text", mquestion.getChoices().get(1).getAnswerBody());
        answerjson.addProperty("votes", 0);
        answerjson2.addProperty("votes", 0);
        answerjson.addProperty("id", mquestion.getId());
        answerjson2.addProperty("id", mquestion.getId());
        answerarray.add(answerjson);
        answerarray.add(answerjson2);

        JsonObject json = new JsonObject();
        json.addProperty("text", mquestion.getQuestionBody());
        json.add("answers", answerarray);
        json.addProperty("user_id", "temp user id");
        final String url = "my endpoint";
        Ion.with(mcontext) //Ion Koush is just a library for making async android requests to a URL  - doubt this is the problem
                .load(url)
                .setJsonObjectBody(json)
                .asJsonObject()
                .setCallback(new FutureCallback<JsonObject>() {
                    @Override
                    public void onCompleted(Exception e, JsonObject result) {
                        if (e != null){
                            Log.d("ConnectToBackend", "postQuestion called with "+url+" and has error" + e.toString());
                            if (result==null){
                                Log.d("ConnectToBackend", "postQuestion returns result with NULL");
                            }
                        }
                        else{
                            //Do Stuff
                        }

                    }
                });
    }

This is an example of what a successful GET to the same endpoint looks like

{"id":5,"answers":[{"id":10,"picture":"someurl","text":"microsoft","votes":0},{"id":9,"picture":"someurl","text":"apple","votes":0}],"created_at":"2015-03-15T04:14:00.782903Z","text":"MicroSoft or Apple","user_id":"8"}

Answer 1

Are you sure it's not actually a string that is successful rather than a dictionary? I've ran into this problem on the Django side, don't know much about Android.

With python it would be:

import json
your_dict = {...}

# this stringifies the dict
json.dumps(your_dict)

I know you're doing this on the client, so the code above won't be your answer, but it's an idea and hopefully it helps!

Answer 2

You can try this in an alternative way by changing the QuestionSerializer:

class QuestionSerializer(serializers.ModelSerializer):
    answers = serializers.SerializerMethodField()

    class Meta:
        model = Question
        fields = ('id', 'answers', 'created_at', 'text', 'user_id',)

    def get_answers(self,obj):
        ans_set = AnswerSerializer(Answer.objects.filter(question=obj),many=True)
        return ans_set