DJango REST framework之分页组件以及对源码的阅读

分页围绕三类

　　a. 分页看第n页，每页显示的n条数据 PageNumberPagination
　　b. 在n个位置，向后查看n条数据 LimitOffsetPagination
　　c. 加密分页上一页和下一页CursorPagination 用户不能随便输入页码，页码已被这个类加密，这个类做的好，它把当前页的最大的id和最小的id的记住，下次在分页的时候根据最大和最小id来，如果不加密的话，假如数据库数据非常多的话，用户万一从当前页直接输入“四九”页，这时候应该数据响应速度慢，MySQL服务器压力太大了。

举例：

表设计

 1 from django.db import models
 2 
 3 
 4 class UserGroup(models.Model):
 5     title = models.CharField(max_length=32)
 6 
 7 
 8 class UserInfo(models.Model):
 9     user_type_choices = (
10         (1, '普通用户'),
11         (2, 'vip'),
12         (3, 'svip'),
13     )
14     user_type = models.IntegerField(choices=user_type_choices)
15     username = models.CharField(max_length=32, unique=True)
16     password = models.CharField(max_length=64)
17     group = models.ForeignKey('UserGroup', on_delete=models.CASCADE)
18     roles = models.ManyToManyField('Role')
19 
20 
21 class UserToken(models.Model):
22     user = models.OneToOneField(to='UserInfo', on_delete=models.CASCADE)
23     token = models.CharField(max_length=64)
24 
25 
26 class Role(models.Model):
27     title = models.CharField(max_length=32)

路由：

1 from django.contrib import admin
2 from django.urls import path, re_path, include
3 
4 urlpatterns = [
5     path('admin/', admin.site.urls),
6     re_path('api/', include('api.urls')),
7 ]

分发：

1 from django.urls import path, re_path, include
2 from api import views
3 
4 urlpatterns = [
5     # 分页
6     re_path('(?P<version>[v1|v2]+)/page1/$', views.Page1View.as_view()),
7 ]

视图以及序列化

 1 class PagerSerializer(serializers.ModelSerializer):
 2     class Meta:
 3         model = models.Role
 4         fields = '__all__'
 5 
 6 
 7 from rest_framework.response import Response
 8 from rest_framework.pagination import PageNumberPagination, LimitOffsetPagination, CursorPagination
 9 
10 
11 class MyPageNumberPagination(PageNumberPagination):
12     """
13     http://api.example.org/accounts/?page=4
14     http://api.example.org/accounts/?page=4&page_size=100
15     """
16     page_size = 2
17     # 自己通过传参定制一页显示多少数据
18     # http://127.0.0.1:8000/api/v1/page1/?page=2&size=3
19     page_size_query_param = 'size'
20     max_page_size = 5
21 
22     page_query_param = 'page'
23 
24 
25 class MyLimitOffsetPagination(LimitOffsetPagination):
26     """
27     http://api.example.org/accounts/?limit=100
28     http://api.example.org/accounts/?offset=400&limit=100
29     """
30     default_limit = 2
31     limit_query_param = 'limit'
32     offset_query_param = 'offset'
33     max_limit = 5
34 
35 
36 class MyCursorPagination(CursorPagination):
37     """
38     "next": "http://127.0.0.1:8000/api/v1/page1/?cursor=cD02",
39     "previous": "http://127.0.0.1:8000/api/v1/page1/?cursor=cj0xJnA9NQ%3D%3D",
40     """
41     cursor_query_param = 'cursor'
42     page_size = 2
43     ordering = 'id'
44     page_size_query_param = None
45     max_page_size = None
46 
47 
48 class Page1View(APIView):
49     def get(self, request, *args, **kwargs):
50         roles = models.Role.objects.all()
51 
52         # pg = PageNumberPagination()
53         # pg = MyPageNumberPagination()
54         # pg = MyLimitOffsetPagination()
55         pg = MyCursorPagination()
56 
57         # 在数据库中获取分页的数据
58         pg_roles = pg.paginate_queryset(queryset=roles, request=request, view=self)
59         # 对数据序列化
60         ser = PagerSerializer(instance=pg_roles, many=True)
61 
62         # 返回两种方式
63         # ret = ser.data
64         # return Response(ret)
65         # 帮我们做了上一页下一页的
66         # "count": 8,
67         # "next": "http://127.0.0.1:8000/api/v1/page1/?page=3&size=3",
68         # "previous": "http://127.0.0.1:8000/api/v1/page1/?size=3",
69         ret = pg.get_paginated_response(ser.data)
70         return ret

全局也可配置：

1 REST_FRAMEWORK = {
2     # 分页
3     'PAGE_SIZE': 2
4 }

内置的分页类：

我觉得这个三个已经够用了。CursorPagination这个重要，而且涉及到了性能。

DJango REST framework之分页组件以及对源码的阅读

分页围绕三类

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