How to retrieve all models data by User id in Django Serializer?

Question

I have following serializers

class UserSerializer(serializers.ModelSerializer):
class Meta:
    model = User
    fields = ['id']


class PersonSerializer(serializers.ModelSerializer):
user = UserSerializer()
comments = CommentSerializer(source='comment_set', many=True)

class Meta:
    model = Person
    fields = '__all__'

And related views

class PersonRetrieveView(generics.RetrieveAPIView):

    queryset = Person.objects.all()
    serializer_class = PersonSerializer


class UserRetrieveView(generics.RetrieveAPIView):

    queryset = User.objects.all()
    serializer_class = UserSerializer
    permission_classes = (permissions.IsAuthenticated, )

The models are standard, Person related to User by Foreign key. So my url path('persons/<int:pk>/', PersonRetrieveView.as_view()), returns Person object with user field with user id. I want to make kinda reverse logic. By user id I want to query all users with field person with all persons related to this user by user id.

I can't just make

class UserSerializer(serializers.ModelSerializer):
person = PersonSerializer()

class Meta:
    model = User
    fields = ['id']

because Person serializer defined below the User serializer. Is there any way to do it simple with generics?

Answer 1

Your models.py should look like this:

class Person(models.Model):
    user = models.ForeignKey(settings.AUTH_USER_MODEL,
               related_name='persons', # This is important
               on_delete=models.CASCADE
           )
    # Other fields...

Then serializers.py:

class PersonSerializer(serializers.ModelSerializer):
    persons=serializers.PrimaryKeyRelatedField(many=True, read_only=True)

    class Meta:
        model = Person

For more info or other relation types you can look at the DRF doc: https://www.django-rest-framework.org/api-guide/relations/