Unable to join two tables with django rest framework - django

Question

I am trying to join two tables and serialize them as an API. I have referred to the docs of the Django rest framework and tried a code. It didn't work. Could not resolve the problem even after trying so many times. I am trying to get a JSON file like
{
'album_name': 'The Grey Album',
'artist': 'Danger Mouse',
'tracks': [
{'order': 1, 'title': 'Public Service Announcement'},
{'order': 2, 'title': 'What More Can I Say'},
{'order': 3, 'title': 'Encore'},
...
],
}
But what I get is
{
'album_name': 'The Grey Album',
'artist': 'Danger Mouse',
}
This is the model file I am using
Model.py
from django.db import models
from django.contrib.auth.models import User
STATUS_CHOICE = (
('simple', 'simple'),
('intermediate', 'intermediate'),
)
class Quiz(models.Model):
quiz_name = models.CharField(max_length=1000)
video_id = models.ForeignKey("youtube.Youtube", on_delete=models.CASCADE)
questions_count = models.IntegerField(default=0)
description = models.CharField(max_length=70, null=True)
created = models.DateTimeField(auto_now_add=True)
slug = models.SlugField()
pass_mark = models.IntegerField()
class Meta:
ordering = ['created']
def __str__(self):
return self.quiz_name
class Category(models.Model):
category = models.CharField(max_length=20, choices=STATUS_CHOICE, default='simple')
quiz_id = models.ForeignKey(Quiz, on_delete=models.CASCADE)
def __str__(self):
return self.category
class Questions(models.Model):
quiz = models.ForeignKey(Quiz, on_delete=models.CASCADE)
question = models.CharField(max_length=1000)
mark = models.IntegerField()
def __str__(self):
return self.question
class Choice(models.Model):
question = models.ForeignKey(Questions, on_delete=models.CASCADE)
choice_1 = models.CharField(max_length=1000)
choice_2 = models.CharField(max_length=1000)
choice_3 = models.CharField(max_length=1000)
choice_4 = models.CharField(max_length=1000)
answer = models.CharField(max_length=1000, default=choice_1)
def __str__(self):
return self.answer
Serializer.py
from rest_framework import serializers
from rest_framework.permissions import IsAuthenticated
from .models import Category, Quiz, Questions, Choice
from django.contrib.auth import authenticate
from django.contrib.auth.hashers import make_password
class QuizSerializer(serializers.ModelSerializer):
class Meta:
model = Quiz
fields = '__all__'
class QuestionsSerializer(serializers.ModelSerializer):
class Meta:
model = Questions
fields = '__all__'
class ChoiceSerializer(serializers.ModelSerializer):
class Meta:
model = Choice
fields = '__all__'
class CategorySerializer(serializers.ModelSerializer):
quiz_name = QuizSerializer(read_only=True)
class Meta:
model = Category
fields = ['id','category','quiz_name']
View.py
from rest_framework import generics, permissions, mixins
from rest_framework.response import Response
from .serializer import CategorySerializer
from .models import Category
class ViewQuiz(generics.ListCreateAPIView):
permission_classes = [
permissions.AllowAny,
]
queryset = Category.objects.all()
serializer_class = CategorySerializer
def list(self, request):
queryset = self.get_queryset()
serializer = CategorySerializer(queryset, many=True)
print(serializer.data)
return Response(serializer.data)

Answer 1

class CategorySerializer(serializers.ModelSerializer):
class Meta:
model = Category
fields = ['id','category','quiz_id']
def to_representation(self, instance):
response = super().to_representation(instance)
response['quiz_id'] = QuizSerializer(instance.quiz_id).data
return response
This will produce the result you want, I made an change in how the serializer represent the data. I have some of my serializer doing the same, but my views are working a bit different from yours.

Answer 2

Looks like you are trying to get questions serializes in quiz.
To do that you need to:
1. In Questions model include related_name in quiz field:
class Questions(models.Model):
quiz = models.ForeignKey(Quiz, on_delete=models.CASCADE, related_name="questions")
question = models.CharField(max_length=1000)
mark = models.IntegerField()
def __str__(self):
return self.question
In QuizSerializer include questions field and set many to True:
class QuizSerializer(serializers.ModelSerializer):
questions = QuestionsSerializer(source="questions", many=True)
class Meta:
model = Quiz
fields = ("questions", ... other needed fields)
Include source attribute in QuizSerializer in CategorySerializer:
class CategorySerializer(serializers.ModelSerializer):
quiz_name = QuizSerializer(read_only=True, source="quiz_id")
class Meta:
model = Category
fields = ['id', 'category', 'quiz_name']
Your Quiz was not serialized because the relation between Category and Quiz in tables are called quiz_id but your field is called quiz_name, so the framework did not know where it should take quiz, because it was looking at quiz_name relation which does not exist.