Example Describing How to Serialize Multiple Models through One Serializer (Case of Foreign Keys) | Django Rest Framework

models.py

from django.db import models


class ModelA(models.Model):
    fieldA1 = models.CharField(max_length=100, unique=True)
    fieldA2 = models.TextField(validators=[URLValidator()], blank=True, null=True)
    fieldA3 = models.CharField(max_length=100, unique=True, null=True, blank=True)
    field4 = models.BooleanField(default=True)


class ModelB(models.Model):
    model_a_field = models.ForeignKey('ModelA', on_delete=models.CASCADE, related_name="model_b_field")
    fieldB1 = models.CharField(max_length=70, null=True, blank=True)
    fieldB2 = models.PositiveIntegerField(default=0)
    fieldB3 = models.BooleanField(default=False)
    field4 = models.BooleanField(default=True)
    

serializers.py

from rest_framework import serializers


class ModelACreateSerializer(serializers.ModelSerializer):
    """
    Serializer to Add ModelA together with ModelB
    """

    class ModelBTempSerializer(serializers.ModelSerializer):
        class Meta:
            model = ModelB
            # 'model_a_field' is a FK which will be assigned after creation of 'ModelA' model entry
            # First entry of ModelB will have (default) fieldB3 value as True, rest as False
            # 'field4' will be derived from its counterpart from the 'Product' model attribute
            exclude = ['model_a_field', 'fieldB3', 'field4']

    model_b = ModelBTempSerializer()  

    class Meta:
        model = ModelA
        fields = '__all__'

    def create(self, validated_data):
        model_b_data = validated_data.pop('model_b')
        model_a_instance = ModelA.objects.create(**validated_data)
        ModelB.objects.create(model_a_field=model_a_instance,
                              fieldB3=True,
                              field4=model_a_instance.field4,
                              **model_b_data)
        return model_a_instance
    

views.py

from rest_framework import generics


class ModelACreateAPIView(generics.CreateAPIView):
    """
    Create a new ModelA entry with ModelB entry
    """
    queryset = ModelA.objects.all()
    serializer_class = ModelACreateSerializer
    

This is a super helpful and easy to understand example since its very well written! Thank you so much!

Hey what would you do if you want something like below?

{
"fieldA1": "",
"fieldA2": "",
"fieldA3": "",
"field4": "",
"fieldB1": "",
"fieldB2": "",
"fieldB3": "",
"field4": "",
}

I don't want to do it with methods.