custom pagination of limit and page in Django Rest Framework - python-3.x

Question

I wanted to create custom paginations for this get_queryset.
get_queryset = Comments.objects.filter(language_post_id=post_in_lang_id,is_post_comment=True).order_by('-created_on')[offset:offset+limit]
I want to change the offset value whenever the page_no updates. Suppose someone enters page_no=1, so offset must be 0, and when enters 2, so offset should be 10, and so on. Every time page_no updates, it should update the offset value accordingly.
like ?page_no=3:
get_queryset = Comments.objects.filter(language_post_id=post_in_lang_id,is_post_comment=True).order_by('-created_on')[offset:offset+limit] # [ 20 : 20 + 10 ]

Answer 1

I guess you want to do that in a ListAPIView. If that's the case, you can do this really simply using PageNumberPagination.Just define the page size and the page_query_param you want, and the default paginate_queryset() method will take care of everything for you, you don't have to override it or calculate the offset by yourself.
# pagination.py
from rest_framework.pagination import PageNumberPagination
class CustomPagination(PageNumberPagination):
# Returns 10 elements per page, and the page query param is named "page_no"
page_size = 10
page_query_param = 'page_no'
# views.py
from rest_framework.generics import ListAPIView
from my_app.pagination import CustomPagination
class MyListView(ListAPIView):
pagination_class = CustomPagination
serializer_class = CommentSerializer
def get_queryset(self):
post_in_lang_id = '1' # Retrieve your post_in_lang_id here
return Comments.objects.filter(language_post_id=post_in_lang_id,is_post_comment=True).order_by('-created_on')
You can also set it as the default paginator by defining DEFAULT_PAGINATION_CLASS in your settings file.
Here is a mock of what you would get as a result for the first page using this method :
{
"count": 20,
"previous": null,
"next": "http://localhost:8000/api/comments/?page_no=2",
"results": [ # List of first 10 elements
{
"id": 1,
[...]
},
[...]
{
"id": 10,
[...]
},
]
}