gistfile1.py

class NestedLazyModelField(serializers.ModelSerializer):
    """
    Use this class for defining a nested relationship based on a funciton
    instead of an attribute.

    For example, 'get_profile' method of user
    """
    def field_to_native(self, obj, field_name):
        obj = getattr(obj, self.source or field_name)

        # FIX: Resolve obj if its callable
        if fields.is_simple_callable(obj):
            obj = obj()

        # If the object has an "all" method, assume it's a relationship
        if fields.is_simple_callable(getattr(obj, 'all', None)):
            return [self.to_native(item) for item in obj.all()]

        return self.to_native(obj)