How to add and serialise additional fields of an existing model in Django

Question

I'm using django-rest-framework and python-social-auth in my Django project.

Here is the serializer class of UserSocialAuth model in my project

class SocialAuthSerializer(serializers.HyperlinkedModelSerializer):
    id = serializers.CharField()

    class Meta:
        model = UserSocialAuth
        fields = ('id', 'provider')

Then I want to an additional field UserSocialAuth.extra_data['login'] to above Serializer, the traditional way should be

class UserSocialAuth(AbstractUserSocialAuth):
    def login:
        return self.extra_data['login']

class SocialAuthSerializer(serializers.HyperlinkedModelSerializer):
    login = serializers.CharField(source='login')
     ...

        fields = ('id', 'provider', 'login')

The problem is that UserSocialAuth is belong to python-social-auth, I have to change the code of python-social-auth app directly to add def login:, so how can I add the additional field to the existing model UserSocialAuth without touching the code of python-social-auth.

Answer 1

I just find that I can use SerializerMethodField here, no need to change the raw class UserSocialAuth, just add one more field to the serializer like this:

class SocialAuthSerializer(serializers.HyperlinkedModelSerializer):
    login = serializers.SerializerMethodField()

    def get_login(self, obj):
        return obj.extra_data['login']