Сериализаторы

# serializers.py

from rest_framework import serializers
from ..models import Subject

class RelatedObjectSerializer(serializers.ModelSerializer)

    class Meta:
        model = SomeModel
        fields = ('...', '...', )

class SubjectSerializer(serializers.ModelSerializer)

    related_object = RelatedObjectSerializer(many=True, read_only=True)

    class Meta:
        model = Subject
        fields = ('id', 'title', 'slug', 'related_object')

class rest_framework.serializers.HyperlinkedModelSerializer

class rest_framework.serializers.ModelSerializer

class rest_framework.serializers.Serializer