How do I make my model's depdent fields appear in my JSON using Django serializers?

Question

I'm using Django 2.0 and Python 3.7. I have the following models ...

from django.db import models

from address.models import AddressField
from phonenumber_field.modelfields import PhoneNumberField
from address.models import State
from address.models import Country


class CoopTypeManager(models.Manager):

    def get_by_natural_key(self, name):
        return self.get_or_create(name=name)[0]


class CoopType(models.Model):
    name = models.CharField(max_length=200, null=False)

    objects = CoopTypeManager()

    class Meta:
        unique_together = ("name",)


class Coop(models.Model):
    name = models.CharField(max_length=250, null=False)
    type = models.ForeignKey(CoopType, on_delete=None)
    address = AddressField(on_delete=models.CASCADE)
    enabled = models.BooleanField(default=True, null=False)
    phone = PhoneNumberField(null=True)
    email = models.EmailField(null=True)
    web_site = models.TextField()

And then I created the following serializers ...

from rest_framework import serializers
from maps.models import Coop, CoopType


class CoopSerializer(serializers.ModelSerializer):
    class Meta:
        model = Coop
        fields = ['id', 'name', 'type', 'address', 'enabled', 'phone', 'email', 'web_site']

    def create(self, validated_data):
        """
        Create and return a new `Snippet` instance, given the validated data.
        """
        return Coop.objects.create(**validated_data)

    def update(self, instance, validated_data):
        """
        Update and return an existing `Coop` instance, given the validated data.
        """
        instance.name = validated_data.get('name', instance.name)
        instance.type = validated_data.get('type', instance.type)
        instance.address = validated_data.get('address', instance.address)
        instance.enabled = validated_data.get('enabled', instance.enabled)
        instance.phone = validated_data.get('phone', instance.phone)
        instance.email = validated_data.get('email', instance.email)
        instance.web_site = validated_data.get('web_site', instance.web_site)
        instance.save()
        return instance

class CoopTypeSerializer(serializers.ModelSerializer):
    class Meta:
        model = CoopType
        fields = ['id', 'name']

    def create(self, validated_data):
        """
        Create and return a new `CoopType` instance, given the validated data.
        """
        return CoopType.objects.create(**validated_data)

    def update(self, instance, validated_data):
        """
        Update and return an existing `Snippet` instance, given the validated data.
        """
        instance.name = validated_data.get('name', instance.name)
        instance.save()
        return instance

I'm trying to create an API to display my models as JSON. I created this views file

from maps.models import Coop
from maps.serializers import CoopSerializer
from django.http import Http404
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import status


class CoopList(APIView):
    """
    List all coops, or create a new coop.
    """
    def get(self, request, format=None):
        coops = Coop.objects.all()
        serializer = CoopSerializer(coops, many=True)
        return Response(serializer.data)

    def post(self, request, format=None):
        serializer = CoopSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)


class CoopDetail(APIView):
    """
    Retrieve, update or delete a coop instance.
    """
    def get_object(self, pk):
        try:
            return Coop.objects.get(pk=pk)
        except Coop.DoesNotExist:
            raise Http404

    def get(self, request, pk, format=None):
        coop = self.get_object(pk)
        serializer = CoopSerializer(coop)
        return Response(serializer.data)

    def put(self, request, pk, format=None):
        coop = self.get_object(pk)
        serializer = CoopSerializer(coop, data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    def delete(self, request, pk, format=None):
        coop = self.get_object(pk)
        coop.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)

However, my dependent model, CoopType, is not getting displayed as JSON. Only its primary key is getting displayed, e.g. ...

{
    "id": 915,
    "name": "Young Men's Educational Network",
    "type": 10,
    "address": 790,
    "enabled": true,
    "phone": null,
    "email": null,
    "web_site": "www.ymenchi.com/"
},

How do I get my dependent model to appear in my JSON?

score 2 · Accepted Answer · answered Feb 19 '20 at 02:54

Override the to_representation(...) method of the Serializer

class CoopSerializer(serializers.ModelSerializer):
    # other code snippets
    def to_representation(self, instance):
        rep = super().to_representation(instance)
        rep['type'] = CoopTypeSerializer(instance.type).data
        return rep

Reference: DRF: Simple foreign key assignment with nested serializers?

How do I make my model's depdent fields appear in my JSON using Django serializers?

1 Answers1