Serializer to include User's Followers in Django Rest Framework

Question

I have the following models:

class User(AbstractUser):
    ...some fields...
    relationships = models.ManyToManyField('self', through='Relationship', symmetrical=False, related_name='related_to')

class Relationship(models.Model):
    from = models.ForeignKey(User, related_name='from')
    to = models.ForeignKey(User, related_name='to')
    type = models.IntegerField()

I have the following User Serializer:

class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ('id', 'username', 'first_name', 'last_name', ...some fields...)
        read_only_field = 'username'

It works great, but now I need to get followers nested with the user. My first attempt was to create a UserBasicSerializer like that:

class UserBasicSerializers(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ('id', 'username', 'first_name', 'last_name')
        read_only_field = 'username'

and add the following to User Serializer:

followers = UserBasicSerializers(required=False, many=True, source='to')

However, I get AttributeError: Relationship object has no attribute first_name

Thank you!

score 2 · Answer 1 · edited May 23 '17 at 11:49

You can see that instead using to related name, you need to use related_to, which is pointing to an actual user object (to is pointing to Relationship object instead). That's why you get this exception.

With a little help of the following tip: https://stackoverflow.com/a/24216503/1566605, you can display nested users:

class RecursiveField(serializers.Serializer):
    def to_native(self, value):
        return self.parent.to_native(value)

class UserSerializer(serializers.ModelSerializer):
    related_to = RecursiveField(many=True)

    class Meta:
        model = User
        fields = ('id', 'username', 'first_name', 'last_name', 'related_to')
        read_only_field = 'username'

Serializer to include User's Followers in Django Rest Framework

1 Answers1