Response pagination (not always performed)

[David Miranda]

Hi,

The pagination in my APIs (ModelViewSet) does not always work. Sometimes returns the paged results and sometimes not (the get_paginated_response method is not executed). I have the settings set pagination class and the PAGE_SIZE parameter. A

Thanks

[Norbert Mate]

Hi,

  does this happen if the result size is smaller than the requested items per page? Example: you have 3 items in the db and from the frontend you request 10.

Regards,

Norbert.

[David Miranda]

Yes! Any suspicion of what might be ?

Regards

[Norbert Mate]

The problem might be that the generic views list method (like ListApiView) returns a list of objects it the page is None.

    def list(self, request, *args, **kwargs):

        queryset = self.filter_queryset(self.get_queryset())

        page = self.paginate_queryset(queryset)

        if page is not None:

            serializer = self.get_serializer(page, many=True)

            return self.get_paginated_response(serializer.data)

        serializer = self.get_serializer(queryset, many=True)

        return Response(serializer.data)

The problem might be in the default pagination class (in PageNumberPagination the page_size_query_param is set to None). To fix this I have created a custom pagination class:

https://gist.github.com/robintema/a2dee269041325d19d47d78853ed4572

Use it by overwriting the default pagination class:

REST_FRAMEWORK = {

…

    'DEFAULT_PAGINATION_CLASS': ‘path.to.pagination.CustomPageNumberPagination',

…

}

[Norbert Mate]

And don't forget to set the page_size query param when you are making the request or set the default page size in the settings:

'PAGE_SIZE': 10,

[David Miranda]

I'm already using a custom pagination class. The problem is that when this happens the list method is not invoked.

[Norbert Mate]

Then I would need more info to be able to try to help. Can you share some code?

[David Miranda]

I recently introduced django cachalot (redis cache). Can be this?

[Norbert Mate]

Disable it and check if the problem still persist.