Django Rest - Item aninhado

gistfile1.txt

class SerializerDaFK(serializers.ModelSerializer):
    """ Serializer com Fields Específicos """

    class Meta:
        model = NomeDoModeldaFK
        fields = ('id',
                  'campo1',
                  'campo2')

class SerializerPrincipal(serializers.ModelSerializer):
    """ Serializer principal """

    field_fk = SerializerDaFK()

    class Meta:
        model = ModelPrincipal
        fields = ('id', 'titulo', 'field_fk')