一、简述
Mixins的几种后端视图.png
Mixins类提供了提供了几种后端视图（对数据资源进行曾删改查）处理流程的实现，如果需要编写的视图属于这五种，则视图可以通过继承相应的扩展类来复用代码，减少自己编写的代码量。这五个扩展类需要搭配GenericAPIView父类，因为五个扩展类的实现需要调用GenericAPIView提供的序列化器与数据库查询的方法。
1.1CreateModelMixin：增加数据
创建视图扩展类，提供create(request, *args, **kwargs)方法快速实现创建资源的视图，成功返回201状态码。如果序列化器对前端发送的数据验证失败，返回400错误。
源码如下：
class CreateModelMixin(object):
"""
Create a model instance.
"""
def create(self, request, *args, **kwargs):
# 获取序列化器
serializer = self.get_serializer(data=request.data)
# 验证
serializer.is_valid(raise_exception=True)
# 保存
self.perform_create(serializer)
headers = self.get_success_headers(serializer.data)
return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
def perform_create(self, serializer):
serializer.save()
def get_success_headers(self, data):
try:
return {'Location': str(data[api_settings.URL_FIELD_NAME])}
except (TypeError, KeyError):
return {}
实例代码：实现增加一条出版社数据
from rest_framework.generics import GenericAPIView
from rest_framework.mixins import CreateModelMixin
from .models import Publisher
from .serializers import PublisherSerializer
from rest_framework.response import Response
# Create your views here.
class PublisherListView(GenericAPIView, CreateModelMixin):
lookup_field = 'pk'
serializer_class = PublisherSerializer
queryset = Publisher.objects.all()
def post(self, request):
return self.create(request)
结果如下：
增加一条数据.png
1.2UpdateModelMixin：更新数据
更新视图扩展类，提供update(request, *args, **kwargs)方法，可以快速实现更新一个存在的数据对象。同时也提供partial_update(request, *args, **kwargs)方法，可以实现局部更新。成功返回200，序列化器校验数据失败时，返回400错误。
源码如下：
class UpdateModelMixin(object):
"""
Update a model instance.
"""
def update(self, request, *args, **kwargs):
partial = kwargs.pop('partial', False)
instance = self.get_object()
serializer = self.get_serializer(instance, data=request.data, partial=partial)
serializer.is_valid(raise_exception=True)
self.perform_update(serializer)
if getattr(instance, '_prefetched_objects_cache', None):
# If 'prefetch_related' has been applied to a queryset, we need to
# forcibly invalidate the prefetch cache on the instance.
instance._prefetched_objects_cache = {}
return Response(serializer.data)
def perform_update(self, serializer):
serializer.save()
def partial_update(self, request, *args, **kwargs):
kwargs['partial'] = True
return self.update(request, *args, **kwargs)
实例代码如下：实现出版社数据更新
from rest_framework.generics import GenericAPIView
from rest_framework.mixins import UpdateModelMixin
from .models import Publisher
from .serializers import PublisherSerializer
from rest_framework.response import Response
# Create your views here.
class PublisherListView(GenericAPIView, UpdateModelMixin):
lookup_field = 'pk'
serializer_class = PublisherSerializer
queryset = Publisher.objects.all()
def put(self, request, pk):
return self.update(request, pk)
更新数据前：
更新前数据.png
调用接口：
调用接口.png
调用接口后：
更新后.png
1.3RetrieveModelMixin：获取单条数据
源码如下：
详情视图扩展类，提供retrieve(request, *args, **kwargs)方法，可以快速实现返回一个存在的数据对象。如果存在，返回200， 否则返回404。
源代码：
class RetrieveModelMixin(object):
"""
Retrieve a model instance.
"""
def retrieve(self, request, *args, **kwargs):
# 获取对象，会检查对象的权限
instance = self.get_object()
# 序列化
serializer = self.get_serializer(instance)
return Response(serializer.data)
实例代码：实现查询单条数据
from rest_framework.generics import GenericAPIView
from rest_framework.mixins import RetrieveModelMixin
from .models import Publisher
from .serializers import PublisherSerializer
from rest_framework.response import Response
# Create your views here.
class PublisherListView(GenericAPIView, RetrieveModelMixin):
lookup_field = 'pk'
serializer_class = PublisherSerializer
queryset = Publisher.objects.all()
def get(self, request, pk):
return self.retrieve(request)
url.py做如下更改
from django.urls import path, re_path
from .views import PublisherListView
urlpatterns = [
path('publisher/list/', PublisherListView.as_view()),
re_path('publisher/list/(?P<pk>[0-9])/', PublisherListView.as_view()),
path('publisher/add/', PublisherListView.as_view()),
re_path('publisher/update/(?P<pk>[0-9])/', PublisherListView.as_view()),
re_path('publisher/delete/(?P<pk>[0-9])/', PublisherListView.as_view())
]
结果如下：
单条数据查询.png
1.4ListModelMixin：获取多条数据
列表视图扩展类，提供list(request, *args, **kwargs)方法快速实现列表视图，返回200状态码。该Mixin的list方法会对数据进行过滤和分页。
源码如下：
class ListModelMixin(object):
"""
List a queryset.
"""
def list(self, request, *args, **kwargs):
# 过滤
queryset = self.filter_queryset(self.get_queryset())
# 分页
page = self.paginate_queryset(queryset)
if page is not None:
serializer = self.get_serializer(page, many=True)
return self.get_paginated_response(serializer.data)
# 序列化
serializer = self.get_serializer(queryset, many=True)
return Response(serializer.data)
实例代码：实现出版社的查询
from rest_framework.generics import GenericAPIView
from rest_framework.mixins import ListModelMixin
from .models import Publisher
from .serializers import PublisherSerializer
from rest_framework.response import Response
# Create your views here.
class PublisherListView(GenericAPIView, ListModelMixin):
lookup_field = 'pk'
serializer_class = PublisherSerializer
queryset = Publisher.objects.all()
def get(self, request):
return self.list(request)
结果如下：
接口返回.png
1.5DestroyModelMixin：删除数据
删除视图扩展类，提供destroy(request, *args, **kwargs)方法，可以快速实现删除一个存在的数据对象。成功返回204，不存在返回404
源代码如下：
class DestroyModelMixin(object):
"""
Destroy a model instance.
"""
def destroy(self, request, *args, **kwargs):
instance = self.get_object()
self.perform_destroy(instance)
return Response(status=status.HTTP_204_NO_CONTENT)
def perform_destroy(self, instance):
instance.delete()
实例代码如下：删除一条出版商数据
from django.shortcuts import render
from rest_framework.generics import GenericAPIView
from rest_framework.mixins import DestroyModelMixin
from .models import Publisher
from .serializers import PublisherSerializer
from rest_framework.response import Response
# Create your views here.
class PublisherListView(GenericAPIView, DestroyModelMixin):
lookup_field = 'pk'
serializer_class = PublisherSerializer
queryset = Publisher.objects.all()
def delete(self, request, pk):
return self.destroy(request, pk)
结果如下：
删除出版商.png
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