视图

5个视图扩展类

视图拓展类的作用:

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)ListModelMixin

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。

源代码:

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)

举例:

from rest_framework.mixins import ListModelMixin

class BookListView(ListModelMixin, GenericAPIView):
queryset = BookInfo.objects.all()
serializer_class = BookInfoSerializer def get(self, request):
return self.list(request)

2)CreateModelMixin

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。

源代码:

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 {}

3)RetrieveModelMixin

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)

举例:

class BookDetailView(RetrieveModelMixin, GenericAPIView):
queryset = BookInfo.objects.all()
serializer_class = BookInfoSerializer def get(self, request, pk):
return self.retrieve(request)

4)UpdateModelMixin

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。

源代码:

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)

5)DestroyModelMixin

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:

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()

使用GenericAPIView和视图扩展类,实现api接口,代码:

"""GenericAPIView结合视图扩展类实现api接口"""
from rest_framework.mixins import ListModelMixin,CreateModelMixin
class Students2GenericAPIView(GenericAPIView,ListModelMixin,CreateModelMixin):
# 本次视图类中要操作的数据[必填]
queryset = Student.objects.all()
# 本次视图类中要调用的默认序列化器[玄天]
serializer_class = StudentModelSerializer def get(self, request):
"""获取多个学生信息"""
return self.list(request) def post(self,request):
"""添加学生信息"""
return self.create(request) from rest_framework.mixins import RetrieveModelMixin,UpdateModelMixin,DestroyModelMixin
class Student2GenericAPIView(GenericAPIView,RetrieveModelMixin,UpdateModelMixin,DestroyModelMixin):
queryset = Student.objects.all() serializer_class = StudentModelSerializer # 在使用GenericAPIView视图获取或操作单个数据时,视图方法中的代表主键的参数最好是pk
def get(self,request,pk):
"""获取一条数据"""
return self.retrieve(request,pk) def put(self,request,pk):
"""更新一条数据"""
return self.update(request,pk) def delete(self,request,pk):
"""删除一条数据"""
return self.destroy(request,pk)

GenericAPIView的视图子类

1)CreateAPIView

提供 post 方法

继承自: GenericAPIView、CreateModelMixin

2)ListAPIView

提供 get 方法

继承自:GenericAPIView、ListModelMixin

3)RetrieveAPIView

提供 get 方法

继承自: GenericAPIView、RetrieveModelMixin

4)DestoryAPIView

提供 delete 方法

继承自:GenericAPIView、DestoryModelMixin

5)UpdateAPIView

提供 put 和 patch 方法

继承自:GenericAPIView、UpdateModelMixin

6)RetrieveUpdateAPIView

提供 get、put、patch方法

继承自: GenericAPIView、RetrieveModelMixin、UpdateModelMixin

7)RetrieveUpdateDestoryAPIView

提供 get、put、patch、delete方法

继承自:GenericAPIView、RetrieveModelMixin、UpdateModelMixin、DestoryModelMixin

from rest_framework.generics import ListAPIView,CreateAPIView,RetrieveAPIView,UpdateAPIView,DestroyAPIView,RetrieveUpdateDestroyAPIView

class BookGenerView2(ListAPIView,):
serializer_class = BookModelSerializer
queryset = Book.objects.all() class BookGenerView3(RetrieveAPIView,):
serializer_class = BookModelSerializer
queryset = Book.objects.all()
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