DRF: Pagination without queryset - django-rest-framework

Question

I am trying to make use of Django Rest Framework's pagination mechanisms in my case without success.
class TransactionView(viewsets.ViewSet):
serializer_class = TransactionSerializer
def list(self, request):
# fetching data from external API...
serializer = self.serializer_class(data=list_of_json, many=True)
if serializer.is_valid():
serializer.save()
return Response(serializer.data)
else:
return Response(serializer.errors)
class TransactionSerializer(serializers.Serializer):
# Serializer (transaction's) fields ...
def create(self, validated_data):
return APITransaction(**validated_data)
class APITransaction(object):
def __init__(self, arg1, arg2, ...):
self.arg1 = arg1
...
The problem is that registering the pagination_class (like I have done for the rest of my resources which are represented by Models), doesn't work since the data are created/fetched on the fly, thus I don't have a Model/queryset.
Any ideas on how I could use DRF's pagination mechanism?

Answer 1

Here's the class I wound up creating and using locally for this sort of thing. (Thanks to stelios above for the initial clues.) Of course the contents of "data" must be JSONable.
from typing import List, Any
from collections import OrderedDict
from django.core.paginator import Paginator
from django.http.response import JsonResponse
from rest_framework.request import Request
class ListPaginator:
def __init__(self, request: Request):
# Hidden HtmlRequest properties/methods found in Request.
self._url_scheme = request.scheme
self._host = request.get_host()
self._path_info = request.path_info
def paginate_list(self, data: List[Any], page_size: int, page_number: int) -> JsonResponse:
paginator = Paginator(data, page_size)
page = paginator.page(page_number)
previous_url = None
next_url = None
if self._host and self._path_info:
if page.has_previous():
previous_url = '{}://{}{}?limit={}&page={}'.format(self._url_scheme, self._host, self._path_info, page_size, page.previous_page_number())
if page.has_next():
next_url = '{}://{}{}?limit={}&page={}'.format(self._url_scheme, self._host, self._path_info, page_size, page.next_page_number())
response_dict = OrderedDict([
('count', len(data)),
('next', next_url),
('previous', previous_url),
('results', page.object_list)
])
return JsonResponse(response_dict, status=200, safe=False)

Answer 2

You can't reuse existing DRF's pagination because they are supposed to work with queryset.
However, you may roll your own class by inheriting BasePagination though I haven't done myself.