Misago/misago/categories/api.py

from rest_framework import viewsets
from rest_framework.response import Response

from .serializers import CategorySerializer
from .utils import get_categories_tree


class CategoryViewSet(viewsets.ViewSet):
    def list(self, request):
        categories_tree = get_categories_tree(request.user)
        return Response(CategorySerializer(categories_tree, many=True).data)