pagination.py

"""
Pagination fields
"""

from rest_framework.pagination import LimitOffsetPagination, PageNumberPagination
from rest_framework.utils.urls import remove_query_param, replace_query_param
from rest_framework.views import Response


class JsonApiPageNumberPagination(PageNumberPagination):
    """
    A JSON:API compatible pagination format.
    """

    page_query_param = "page[number]"
    page_size_query_param = "page[size]"
    max_page_size = 100

    def build_link(self, index):
        if not index:
            return None
        url = self.request and self.request.build_absolute_uri() or ""
        return replace_query_param(url, self.page_query_param, index)

    def get_paginated_response(self, data):
        next = None
        previous = None

        if self.page.has_next():
            next = self.page.next_page_number()
        if self.page.has_previous():
            previous = self.page.previous_page_number()

        return Response(
            {
                "results": data,
                "meta": {
                    "pagination": {
                        "page": self.page.number,
                        "pages": self.page.paginator.num_pages,
                        "count": self.page.paginator.count,
                    }
                },
                "links": {
                    "first": self.build_link(1),
                    "last": self.build_link(self.page.paginator.num_pages),
                    "next": self.build_link(next),
                    "prev": self.build_link(previous),
                },
            }
        )


class JsonApiLimitOffsetPagination(LimitOffsetPagination):
    """
    A limit/offset based style. For example:

    .. code::

        http://api.example.org/accounts/?page[limit]=100
        http://api.example.org/accounts/?page[offset]=400&page[limit]=100

    """

    limit_query_param = "page[limit]"
    offset_query_param = "page[offset]"
    max_limit = 100

    def get_last_link(self):
        if self.count == 0:
            return None

        url = self.request.build_absolute_uri()
        url = replace_query_param(url, self.limit_query_param, self.limit)

        offset = (self.count // self.limit) * self.limit

        if offset <= 0:
            return remove_query_param(url, self.offset_query_param)

        return replace_query_param(url, self.offset_query_param, offset)

    def get_first_link(self):
        if self.count == 0:
            return None

        url = self.request.build_absolute_uri()
        return remove_query_param(url, self.offset_query_param)

    def get_paginated_response(self, data):
        return Response(
            {
                "results": data,
                "meta": {
                    "pagination": {
                        "count": self.count,
                        "limit": self.limit,
                        "offset": self.offset,
                    }
                },
                "links": {
                    "first": self.get_first_link(),
                    "last": self.get_last_link(),
                    "next": self.get_next_link(),
                    "prev": self.get_previous_link(),
                },
            }
        )