DRF之分页器
一. DRF分页器
我们数据库有几千万条数据,这些数据需要展示,我们不可能直接从数据库把数据全部读取出来,这样会给内存造成特别大的压力,有可能还会内存溢出,所以我们希望一点一点的取,那展示的时候也是一样的,总是要进行分页显示。
DRF给我们提供了三种分页方式,我们看下他们都是什么样的。
1.分页组件的使用
DRF提供的三种分页:
from rest_framework.pagination import PageNumberPagination, LimitOffsetPagination, CursorPagination
第一种 PageNumberPagination 看第n页,每页显示n条数据
路由进行了一层分发:
path('pagination/', include('pagination.urls'))
urls:
from django.urls import path from pagination.views import PageView urlpatterns = [ path('test/', PageView.as_view()) ]
自己写的分页器类:
from rest_framework.pagination import PageNumberPagination class MyPagination(PageNumberPagination):
page_size = 2 # 每页显示多少条
page_size_query_param = 'size' # URL中每页显示条数的参数
page_query_param = 'page' # URL中页码的参数
max_page_size = None # 最大页码数限制
views:
from rest_framework.views import APIView from utiles.pagination import MyPagination from xuliehua import models from xuliehua.serializers import BookModelSerializer # Create your views here. class PageView(APIView): def get(self, request): queryset = models.Book.objects.all() page_obj = MyPagination() page_queryset = page_obj.paginate_queryset(queryset=queryset, request=request, view=self) ret = BookModelSerializer(page_queryset,many=True) return page_obj.get_paginated_response(ret.data)
特别注意:
1. 通过 page_obj.get_paginated_response(ret.data)的方法返回的数据,会带有吓一跳路径。
{ "count": 3, "next": "http://127.0.0.1:8000/pagination/test/?page=2", "previous": null, "results": [ { "id": 1, "category_display": "Python", "publisher_info": { "id": 1, "title": "北京出版社" }, "authors": [ { "id": 1, "name": "alex" }, { "id": 2, "name": "wupeiqi" } ], "title": "python全栈开发2", "pub_time": "2020-10-14" }, { "id": 2, "category_display": "Linux", "publisher_info": { "id": 2, "title": "上海出版社" }, "authors": [ { "id": 1, "name": "alex" } ], "title": "数据库基础", "pub_time": "2020-10-01" } ] }
第二种 LimitOffsetPagination 在第n个位置 向后查看n条数据
from rest_framework.pagination import LimitOffsetPagination
class MyLimitOffset(LimitOffsetPagination): default_limit = 1 limit_query_param = 'limit' offset_query_param = 'offset' max_limit = 999
第三种 CursorPagination 加密游标的分页 把上一页和下一页的id记住
from rest_framework.pagination import CursorPagination
class MyCursorPagination(CursorPagination): cursor_query_param = 'cursor' page_size = 1 ordering = '-id'