drf : 過濾 排序 分頁
阿新 • • 發佈：2022-04-11
目錄
過濾和排序
並不是所有的介面都需要寫，查詢所有才需要過濾(根據條件過濾)，排序(按某個規則排序，也可倒序)。
匯入模組：
"""
OrderingFilter : 排序
SearchFilter : 過濾
"""
from rest_framework.filters import OrderingFilter,SearchFilter
過濾，內建的過濾，必須繼承GenericAPIView，才會有這個類屬性。
作用：模糊匹配原則，查詢關鍵字只能為search
views.py
from rest_framework.filters import SearchFilter class BookAPIView(ViewSetMixin,ListAPIView): queryset = Books.objects.all() serializer_class = BookSerializers # 在檢視類中配置，最頂層至少是GenericAPIView，GenericAPIView中有filter_backends filter_backends = [SearchFilter,] # 過濾條件：按自釘子欄位過濾 search_fields = ['price']
排序
view.py
from rest_framework.filters import OrderingFilter class BookAPIView(ViewSetMixin,ListAPIView): queryset = Books.objects.all() serializer_class = BookSerializers # 在檢視類中配置，最頂層至少是GenericAPIView，GenericAPIView中有filter_backends filter_backends = [OrderingFilter] # 按照那個欄位排序 ordering_fields = ['id']
過濾和排序組合
views.py
"""
OrderingFilter : 排序
SearchFilter : 過濾
"""
from rest_framework.filters import OrderingFilter,SearchFilter
class BookAPIView(ViewSetMixin,ListAPIView):
queryset = Books.objects.all()
serializer_class = BookSerializers
# 在檢視類中配置，最頂層至少是GenericAPIView，GenericAPIView中有filter_backends
filter_backends = [SearchFilter,OrderingFilter]
# 過濾條件：按名字過濾
search_fields = ['name']
# 按照那個欄位排序
ordering_fields = ['id']
# 排序可以多個條件排序，前提第一個條件要一直
ordering_fields = ['id','price']
按照name欄位(西)過濾，按到id欄位倒序過濾，正序不用加-。
如果多個條件排序: http://127.0.0.1:8000/books/?ordering=-id,100
第三方過濾
作用：只能精準匹配，查詢字為欄位名。
安裝：
pip install django-filter
匯入模組：
from django_filters.rest_framework import DjangoFilterBackend
註冊：
INSTALLED_APPS = [
'django_filters'
]
views.py，檢視層
from django_filters.rest_framework import DjangoFilterBackend
class BookAPIView(ViewSetMixin, ListAPIView):
queryset = Books.objects.all()
serializer_class = BookSerializers
filter_backends = [DjangoFilterBackend, ]
# 過濾條件：按名字過濾
filterset_fields = ['name']
# 按照那個欄位排序
ordering_fields = ['id']
第三方過濾查詢多個
自定義過濾器
作用：模糊匹配與精準匹配，查詢關鍵字為欄位名。
開設一個filter.py檔案。
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)
"""
過濾前的資料
<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)
"""
過濾後的資料。
<QuerySet
[<Books: Books object (1)>,
<Books: Books object (2)>,
<Books: Books object (3)>]>
"""
print(queryset)
return queryset
views.py
from .filter import MyFilter
# 自定義過濾
class BookAPIView(ViewSetMixin, ListAPIView):
queryset = Books.objects.all()
serializer_class = BookSerializers
filter_backends = [MyFilter, ]
分頁
首先：在五個介面中，只有查詢所有才涉及到分頁。
預設提供三種分頁方式：
- PageNumberPagination
- LimitOffsetPagination
- CursorPagination
匯入模組
from rest_framework.pagination import PageNumberPagination,CursorPagination,LimitOffsetPagination
基本分頁，使用頻率高：PageNumberPagination
匯入模組:
from rest_framework.pagination import PageNumberPagination
需要重寫PageNumberPagination中的四個類方法。
page.py
from rest_framework.pagination import PageNumberPagination, CursorPagination, LimitOffsetPagination
class MyPageNumberPagination(PageNumberPagination):
# 每頁顯示條數
page_size = 3
# 查詢條件為page --> ?page=頁數
page_query_param = 'page'
# 每頁顯示的條數的查詢條件，?page=3&size=9 查詢第三頁，第三頁顯示9條
page_size_query_param = 'size'
# 控制每頁上限資料為幾條
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
# 自定義過濾
class BookAPIView(ViewSetMixin, ListAPIView):
queryset = Books.objects.all()
serializer_class = BookSerializers
filter_backends = [MyFilter, ]
# 分頁只要一種方式，必須繼承GenericAPIView類
pagination_class = MyPageNumberPagination
舉例:
偏移分頁: LimitOffsetPagination
匯入模組：
from rest_framework.pagination import LimitOffsetPagination
page.py
class MyLimitOffsetPagination(LimitOffsetPagination):
# 預設每頁顯示資料為幾條
default_limit = 3
# 當前頁獲取幾條資料: ?limit=3 , 如果沒有寫使用預設 default_limit
limit_query_param = 'limit'
# ?limit=3&offset=2 從第二條資料開始但不包括第二條資料向下展示三條。
offset_query_param = 'offset'
# 最大顯示條數
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
# 自定義過濾
class BookAPIView(ViewSetMixin, ListAPIView):
queryset = Books.objects.all()
serializer_class = BookSerializers
filter_backends = [MyFilter, ]
# 分頁只要一種方式，必須繼承GenericAPIView類
pagination_class = MyLimitOffsetPagination
CursorPagination,一般用作體量非常大或者手機端的查詢。
作用：只能選擇上一頁和下一頁，不能指定某一頁，但是查詢速度快。大資料量和app分頁不需要指定指定跳轉到第幾頁，下拉載入下一頁即可。
page.py
from rest_framework.pagination import CursorPagination
class MyCursorPagination(CursorPagination):
# 預設每頁顯示條數
page_size = 3
# 查詢關鍵字?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, ]
# 分頁只要一種方式，必須繼承GenericAPIView類
pagination_class = MyCursorPagination
總結：PageNumberPagination，LimitOffsetPagination，CursorPagination。三者區別。
PageNumberPagination,LimitOffsetPagination: 可以從中間位置獲取到某一頁，CursorPagination分頁只能獲取上一頁和下一頁。
PageNumberPagination,LimitOffsetPagination:獲取到某一頁時，需要從開始過濾到要取的頁面數的資料。CursorPagination在取到某一頁時不用過濾之前的資料。