from __future__ import unicode_literals from rest_framework import serializers from .models import Folder class FolderSerializer(serializers.ModelSerializer): documents = serializers.SerializerMethodField('get_documents_count') class Meta: fields = ('id', 'title', 'user', 'datetime_created', 'documents') model = Folder read_only_fields = ('user',) def get_documents_count(self, obj): return obj.documents.count()