drf : 过滤 排序 分页

过滤和排序

并不是所有的接口都需要写，查询所有才需要过滤(根据条件过滤)，排序(按某个规则排序，也可倒序)。

导入模块：

"""
OrderingFilter : 排序
SearchFilter : 过滤
"""
from rest_framework.filters import OrderingFilter,SearchFilter

过滤，内置的过滤，必须继承GenericAPIView，才会有这个类属性。

作用：模糊匹配原则，查询关键字只能为search

views.py

from rest_framework.filters import SearchFilter
class BookAPIView(ViewSetMixin,ListAPIView):
    queryset = Books.objects.all()
    serializer_class = BookSerializers
    # 在视图类中配置，最顶层至少是GenericAPIView，GenericAPIView中有filter_backends
    filter_backends = [SearchFilter,]
    # 过滤条件：按自钉子字段过滤
    search_fields = ['price']
 

排序

view.py

from rest_framework.filters import OrderingFilter
class BookAPIView(ViewSetMixin,ListAPIView):
    queryset = Books.objects.all()
    serializer_class = BookSerializers
    # 在视图类中配置，最顶层至少是GenericAPIView，GenericAPIView中有filter_backends
    filter_backends = [OrderingFilter]
    # 按照那个字段排序
    ordering_fields = ['id']

过滤和排序组合

views.py

 
"""
OrderingFilter : 排序
SearchFilter : 过滤
"""
from rest_framework.filters import OrderingFilter,SearchFilter
class BookAPIView(ViewSetMixin,ListAPIView):
    queryset = Books.objects.all()
    serializer_class = BookSerializers
    # 在视图类中配置，最顶层至少是GenericAPIView，GenericAPIView中有filter_backends
    filter_backends = [SearchFilter,OrderingFilter]
    # 过滤条件：按名字过滤
    search_fields = ['name']
    # 按照那个字段排序
    ordering_fields = ['id']
    # 排序可以多个条件排序，前提第一个条件要一直
    ordering_fields = ['id','price']

按照name字段(西)过滤，按到id字段倒序过滤，正序不用加-。

如果多个条件排序: http://127.0.0.1:8000/books/?ordering=-id,100

第三方过滤

作用：只能精准匹配，查询字为字段名。

安装：

pip install django-filter

导入模块：

from django_filters.rest_framework import DjangoFilterBackend

注册：

INSTALLED_APPS = [
    'django_filters'
]

views.py，视图层

from django_filters.rest_framework import DjangoFilterBackend
 
 
class BookAPIView(ViewSetMixin, ListAPIView):
    queryset = Books.objects.all()
    serializer_class = BookSerializers
    filter_backends = [DjangoFilterBackend, ]
    # 过滤条件：按名字过滤
    filterset_fields = ['name']
    # 按照那个字段排序
    ordering_fields = ['id']

第三方过滤查询多个

自定义过滤器

作用：模糊匹配与精准匹配，查询关键字为字段名。

开设一个filter.py文件。

 
from rest_framework.filters import BaseFilterBackend
 
 
class MyFilter(BaseFilterBackend):
    def filter_queryset(self, request, queryset, view):
        # <rest_framework.request.Request: GET '/books/?name=%E8%A5%BF'>
        print(request)
        """
        过滤前的数据
        <QuerySet 
        [<Books: Books object (1)>, 
        <Books: Books object (2)>, 
        <Books: Books object (3)>, 
        <Books: Books object (4)>, 
        <Books: Books object (5)>]>
        """
        print(queryset)
        query = request.query_params.get('name')
 
        if query:
            # 西
            print(query)
            queryset = queryset.filter(name__contains=query)
            """
            过滤后的数据。
            <QuerySet 
            [<Books: Books object (1)>, 
            <Books: Books object (2)>, 
            <Books: Books object (3)>]>
            """
            print(queryset)
        return queryset

views.py

from .filter import MyFilter

自定义过滤

class BookAPIView(ViewSetMixin, ListAPIView):
    queryset = Books.objects.all()
    serializer_class = BookSerializers
    filter_backends = [MyFilter, ]

分页

首先：在五个接口中，只有查询所有才涉及到分页。

默认提供三种分页方式：

• PageNumberPagination
• LimitOffsetPagination
• CursorPagination
  导入模块

from rest_framework.pagination import PageNumberPagination,CursorPagination,LimitOffsetPagination

基本分页，使用频率高：PageNumberPagination

导入模块:

from rest_framework.pagination import PageNumberPagination

需要重写PageNumberPagination中的四个类方法。

page.py

from rest_framework.pagination import PageNumberPagination, CursorPagination, LimitOffsetPagination
class MyPageNumberPagination(PageNumberPagination):
    # 每页显示条数
    page_size = 3
	  # 查询条件为page --> ?page=页数
    page_query_param = 'page'  
		 # 每页显示的条数的查询条件，?page=3&size=9 查询第三页，第三页显示9条
    page_size_query_param = 'size' 
		# 控制每页上限数据为几条
    max_page_size = 5 

views.py

from rest_framework.generics import ListAPIView
from rest_framework.viewsets import ViewSetMixin
from .filter import MyFilter
from .page import MyPageNumberPagination
 
# 自定义过滤
class BookAPIView(ViewSetMixin, ListAPIView):
    queryset = Books.objects.all()
    serializer_class = BookSerializers
    filter_backends = [MyFilter, ]
    # 分页只要一种方式，必须继承GenericAPIView类
    pagination_class = MyPageNumberPagination

举例:

偏移分页: LimitOffsetPagination

导入模块：

from rest_framework.pagination import LimitOffsetPagination

page.py

class MyLimitOffsetPagination(LimitOffsetPagination):
    # 默认每页显示数据为几条
    default_limit = 3
    # 当前页获取几条数据: ?limit=3 , 如果没有写使用默认 default_limit
    limit_query_param = 'limit'
    # ?limit=3&offset=2 从第二条数据开始但不包括第二条数据向下展示三条。
    offset_query_param = 'offset'
    # 最大显示条数
    max_limit = 5

views.py

from rest_framework.generics import ListAPIView
from rest_framework.viewsets import ViewSetMixin
from .filter import MyFilter
from .page import MyPageNumberPagination,MyLimitOffsetPagination
 
# 自定义过滤
class BookAPIView(ViewSetMixin, ListAPIView):
    queryset = Books.objects.all()
    serializer_class = BookSerializers
    filter_backends = [MyFilter, ]
    # 分页只要一种方式，必须继承GenericAPIView类
    pagination_class = MyLimitOffsetPagination

CursorPagination,一般用作体量非常大或者手机端的查询。

作用：只能选择上一页和下一页，不能指定某一页，但是查询速度快。大数据量和app分页不需要指定指定跳转到第几页，下拉加载下一页即可。

page.py

from rest_framework.pagination import CursorPagination
 
 
class MyCursorPagination(CursorPagination):
    # 默认每页显示条数
    page_size = 3
    # 查询关键字?cursor=cD0z
    cursor_query_param = 'cursor'
    # 排序，正向或者倒序
    ordering = 'id'

views.py

from rest_framework.generics import ListAPIView
from rest_framework.viewsets import ViewSetMixin
from .filter import MyFilter
from .page import MyCursorPagination
 
class BookAPIView(ViewSetMixin, ListAPIView):
    queryset = Books.objects.all()
    serializer_class = BookSerializers
    filter_backends = [MyFilter, ]
    # 分页只要一种方式，必须继承GenericAPIView类
    pagination_class = MyCursorPagination

总结：PageNumberPagination，LimitOffsetPagination，CursorPagination。三者区别。

PageNumberPagination,LimitOffsetPagination: 可以从中间位置获取到某一页，CursorPagination分页只能获取上一页和下一页。

PageNumberPagination,LimitOffsetPagination:获取到某一页时，需要从开始过滤到要取的页面数的数据。CursorPagination在取到某一页时不用过滤之前的数据。

分类: drf