allow setting a custom Django Paginator in pagination.PageNumberPagin…

[syphar]

…ation

[xordoquy]

What's the motivation behind that change ? Why isn't the django validator enough ?

[syphar]

@xordoquy in our codebase we are using a different Django Paginator for some bigger tables (where the count(*) takes too much time, and an estimated page-count is enough.

This would help us setting our own paginator without having to copy/paste the paginate_queryset method

[lovelydinosaur]

Out of curiosity, what do you use for estimated page counts?
Also, is modifying get_paginated_response an alternative here, or is that not sufficient?

Follow up... I guess num_pages performs a count() - might be good if we could avoid that?

[syphar]

we are using the postgres statistics for this table. it has currently around 3 Mio records, and the rough value is exact enough.

we already have modified get_paginated_response (similar to the Header based example in the docs, which removes one call to Paginator.count.

But paginate_queryset calls Paginator.num_pages, which also calls Paginator.count.

(a count in these specific tables takes around 2-3 seconds)

[xordoquy]

Sounds sensible to me.
Would probably rename the django_paginator_class to simply paginator_class

[lovelydinosaur]

django_paginator_class seems right - differentiate from our pagination controls.
I'm not 100% convinced if we want to add public API around this or not, but on balance I guess probably okay as-is.

[lovelydinosaur]

But paginate_queryset calls Paginator.num_pages, which also calls Paginator.count.

Indeed. Making this easier to eliminate might be a good plan

[lovelydinosaur]

Milestoning to push this to the top for a final review.

[lovelydinosaur]

Thanks @syphar!

[syphar]

thanks @tomchristie and @xordoquy :)