小记， django select 字段中含有连表查询分页优化

例如查询每本书的借阅数量，在 select 中加入连表

select id,(select count(*) from book where book.user_id= user.id) as count,name from user;

在 django 分页最后会变成

select count(*) from (
select id,(select count(*) from book where book.user_id= user.id) as count,name from user)

优化,在 restframework 中分页, 去掉 select 字段，只保留 filter 条件

from rest_framework.pagination import PageNumberPagination
from django.core.paginator import Paginator
from django.utils.functional import cached_property

class Pagination(Paginator):

    @cached_property
    def count(self):
        """Return the total number of objects, across all pages."""
        c = getattr(self.object_list, 'count', None)
        if callable(c) and not inspect.isbuiltin(c) and method_has_no_args(c):
            return self.object_list.values('id').count()
        return len(self.object_list)


class CustomPagination(PageNumberPagination):
    django_paginator_class = TicketPagination

接口中使用

class API(ModelViewSet):
  pagination_class = CustomPagination

小记， django select 字段中含有连表查询 分页优化

小记， django select 字段中含有连表查询分页优化