四：drf视图组件
一. 前言
Django REST framwork 提供的视图的主要作用
1. 控制序列化器的执行（检验、保存、转换数据）
2. 控制数据库查询的执行
二. 两个视图基类
两个视图基类: APIView, GenericAPIView
1. APIView
1) models.py
class Book(models.Model):
name = models.CharField(max_length=32, null=True)
price = models.DecimalField(max_digits=8, decimal_places=2, null=True)
author = models.CharField(max_length=32, null=True)
publish = models.CharField(max_length=32, null=True)
2) serializer.py 自定义序列化.py文件
from rest_framework import serializers
from .models import Book
def check_name(data):
return data
class BookSerializer(serializers.Serializer):
nid = serializers.CharField(read_only=True, source='pk')
name = serializers.CharField(required=True, error_messages={
'required': '必须输入内容'
}, validators=[check_name])
price = serializers.DecimalField(max_digits=8, decimal_places=2, max_value=1000000, min_value=1)
author = serializers.CharField(max_length=32, min_length=0, trim_whitespace=True)
publish = serializers.CharField(allow_blank=True)
def update(self, instance, validate_data):
for key, value in validate_data.items():
if hasattr(instance, key):
setattr(instance, key, value)
instance.save()
return instance
def create(self, validate_data):
return Book.objects.create(**validate_data)
3) views.py
# 自定义封装的SelfResponse类
'''
from rest_framework.response import Response
class SelfResponse(Response):
def __init__(self, status=1000, messages='成功', results=None, error=None, *args, **kwargs):
self.data = {
'status': status,
'messages': messages,
}
if results:
self.data['results'] = results
elif results:
self.data['error'] = error
super().__init__(data=self.data, *args, **kwargs)
'''
from rest_framework.views import APIView
from rest_framework.renderers import JSONRenderer
from .models import Book
from .serializer import BookSerializer
from drf_views.utils import SelfResponse
# Create your views here.
class BookListCreateView(APIView):
# 控制响应格式. 默认有2种: 一种响应浏览器, 一种响应json格式数据
renderer_classes = [JSONRenderer]
def get(self, request):
book_queryset = Book.objects.filter()
serializer = BookSerializer(instance=book_queryset, many=True)
return SelfResponse(results=serializer.data)
def post(self, request):
serializer = BookSerializer(data=request.data)
if serializer.is_valid():
serializer.save()
obj = SelfResponse(results=serializer.data)
else:
obj = SelfResponse(2000, '失败', error=serializer.errors)
return obj
class BookDestroyRetrieveUpdate(APIView):
def get(self, request, pk):
book_obj = Book.objects.filter(pk=pk).first()
serializer = BookSerializer(instance=book_obj)
return SelfResponse(results=serializer.data)
def put(self, request, pk):
book_obj = Book.objects.filter(pk=pk).first()
serializer = BookSerializer(instance=book_obj, data=request.data)
if serializer.is_valid():
serializer.save()
obj = SelfResponse(results=serializer.data)
else:
obj = SelfResponse(2000, '失败', error=serializer.errors)
return obj
def delete(self, request, pk):
Book.objects.filter(pk=pk).delete()
return SelfResponse()
4) urls.py
Copyfrom django.conf.urls import url
from .views import BookListCreateView
from .views import BookDestroyRetrieveUpdate
urlpatterns = [
url(r'^books/$', BookListCreateView.as_view()),
url(r'^books/(?P<pk>\d+)', BookDestroyRetrieveUpdate.as_view()),
]
5) 总结
1. 继承关系: APIView继承View
2. APIView基于View的拓展:
APIView重写了View的dispatch方法, 在该方法中实现了实现了一下功能:
1) 对来的原生请求对象request进行了封装.
2) 提供了对包装过后的请求对象的三段认证: 认证, 权限控制, 频率控制
3) 重写了View中通过本次请求的方式动态的反射到自定义继承APIView类实例化的对象中定义的请求方法
4) 使用异常处理处理2,3步骤中的异常
5) 处理完毕异常以后使用drf的response对象对请求响应
3. 针对路由配置
路由中的有名分组必须指定pk, 视图中使用必须使用相同的关键字参数接受
2. GenericAPIView和5个视图扩展类写的接口#
1) models.py
from django.db import models
# Create your models here.
class Book(models.Model):
name = models.CharField(max_length=32, null=True)
price = models.DecimalField(max_digits=8, decimal_places=2, null=True)
author = models.CharField(max_length=32, null=True)
publish = models.CharField(max_length=32, null=True)
publish_time = models.DateTimeField(auto_now_add=True)
2) serializer.py 自定义序列化.py文件#
from rest_framework import serializers
from .models import Book
class BookModelSerializer(serializers.ModelSerializer):
class Meta:
model = Book
fields = '__all__'
# exclude = ('id', )
# exclude = ['id']
extra_kwargs = {
# 'price': {'write_only': True}
}
read_only_fields = ['id', ]
# 该方式在drf3.2版本以后就被弃用了, 使用ModelSerializer现在使用的的extra_kwargs
# write_only_fields = []
3) views.py
# 自定义封装的SelfResponse类
'''
from rest_framework.response import Response
class SelfResponse(Response):
def __init__(self, status=1000, messages='成功', results=None, error=None, *args, **kwargs):
self.data = {
'status': status,
'messages': messages,
}
if results:
self.data['results'] = results
elif results:
self.data['error'] = error
super().__init__(data=self.data, *args, **kwargs)
'''
from rest_framework.generics import GenericAPIView
from drf_views.utils import SelfResponse
from .models import Book
from .serializer import BookModelSerializer
# Create your views here.
class BookListCrateView(GenericAPIView):
# queryset = Book.objects.all()
queryset = Book.objects
serializer_class = BookModelSerializer
def get(self, request):
book_obj = self.get_queryset()
serializer = self.get_serializer(instance=book_obj, many=True)
return SelfResponse(results=serializer.data)
def post(self, request):
serializer = self.get_serializer(data=request.data)
if serializer.is_valid():
serializer.save()
obj = SelfResponse(results=serializer.data)
else:
obj = SelfResponse(2000, '失败', error=serializer.errors)
return obj
class BookUpdateDestroyRetrieve(GenericAPIView):
queryset = Book.objects
serializer_class = BookModelSerializer
lookup_url_kwarg = 'www'
def get(self, request, www):
book_obj = self.get_object()
serializer = self.get_serializer(instance=book_obj)
return SelfResponse(results=serializer.data)
def put(self, request, pk):
book_obj = self.get_object()
serializer = self.get_serializer(instance=book_obj, data=request.data)
if serializer.is_valid():
serializer.save()
obj = SelfResponse(results=serializer.data)
else:
obj = SelfResponse(2000, '失败', error=serializer.errors)
return obj
def delete(self, request, pk):
self.get_object().delete()
return SelfResponse()
4) GenericAPIView提供的三种方法的源码分析
# 1. self.get_queryset
def get_queryset(self):
# 1) 断言继承GenericAPIView的视图类实例化的对象时候有queryset对象
'''
如果没有: 那么断言成功抛出异常
如果有: 那么将会继续往下执行
因此为什么视图类中要为类新增一个queryset属性的原因就明白了
'''
assert self.queryset is not None, (
"'%s' should either include a `queryset` attribute, "
"or override the `get_queryset()` method."
% self.__class__.__name__
)
# 2) 由自定义视图类实例化出来的对象获取类中定义的queryset对象. 进行判断
''''
如果我们自定义视图类中书写的属性是queryset对象, 那么就会帮我们自动.all(). 因此我们可以不用点all了.
如果不是, 那么就直接返回数据对象
'''
queryset = self.queryset
if isinstance(queryset, QuerySet):
# Ensure queryset is re-evaluated on each request.
queryset = queryset.all()
return queryset
# 2. self.get_serializer
def get_serializer(self, *args, **kwargs):
# 1) 获取继承GenericAPIView视图类实例化对象中找get_serializer_class
'''
def get_serializer_class(self):
# ① 断言继承GenericAPIVIew的自定义视图类实例化出来的对象中serializer_class时候为None
'''
为None断言成功, 抛出指定异常
不为None断言失败, 继续往下执行
'''
assert self.serializer_class is not None, (
"'%s' should either include a `serializer_class` attribute, "
"or override the `get_serializer_class()` method."
% self.__class__.__name__
)
# ② 发现本质就是获取视图类中定义的serializer_class序列化器类, 因此从这里我们就明白为什么视图类中要写序列化器类了.
return self.serializer_class
'''
# 2) get_serializer_class方法就是获取到了我们自定义视图类中定义的serializer_classes属性
serializer_class = self.get_serializer_class()
# 3) 内部就是return, 获取我们自定义视图类中的上下文一些信息
'''
def get_serializer_context(self):
return {
'request': self.request,
'format': self.format_kwarg,
'view': self
}
'''
kwargs['context'] = self.get_serializer_context()
# 4) 这里的serializer_class就是自定义视图类中的类属性, 通过类属性调用传值
return serializer_class(*args, **kwargs)
# 3. self.get_object
def get_object(self):
# 1) 执行过滤操作, 默认没有配置过滤类. 因此queryset还是queryset
queryset = self.filter_queryset(self.get_queryset())
# 2) 运用短路运算, lookup_url_kwarg默认就是None, lookup_field默认就是pk, 因此返回值就是pk
'''
提示: 继承GenericAPIView的自定义视图类中没有定义以下参数. 默认使用的是GenericAPIView类中配置的
lookup_field = 'pk'
lookup_url_kwarg = None
'''
lookup_url_kwarg = self.lookup_url_kwarg or self.lookup_field
# 3) 断言刚刚的pk时候在self.kwargs中
'''
查找顺序: 视图对象 -> 视图类 -> GenericAPIView -> APIView -> dispatch.
kwargs就是路由匹配来了, 走到APIVIew中的dispatch方法中将传入的关键字参数形式的key:value对到kwargs字典中,
再存到的对象当中, 直至此刻拿出来进行判断.
本质就是必须安装关键字pk=xxx的形式传参, 路由中必须指定又名分组pk, 视图中必须指定接受的关键字参数是pk
'''
assert lookup_url_kwarg in self.kwargs, (
'Expected view %s to be called with a URL keyword argument '
'named "%s". Fix your URL conf, or set the `.lookup_field` '
'attribute on the view correctly.' %
(self.__class__.__name__, lookup_url_kwarg)
)
# 4) 这里就是获取默认定义lookup_field充当字典的key, 又从self.kwargs这个dispatch方法就赋值的字典中, 将通过key取值, lookup_url_kwarg就是第2步分析出来的值
filter_kwargs = {self.lookup_field: self.kwargs[lookup_url_kwarg]}
# 5) get_object_or_404的功能就是获取对象 或者 抛出抛出404异常
'''
**filter_kwargs就是步骤4的字典. 字典的结构{'pk': value},
**就将字典拆散, 以关键字的形式传参, 传给了get_object_or_404方法
def get_object_or_404(queryset, *filter_args, **filter_kwargs):
try:
# _get_object_or_404内部就是从闯传进来的queryset对象中使用get以关键字的形式查询,但是get方法会在2种情况下, 会抛出异常, 因此内部也做了异常处理
return _get_object_or_404(queryset, *filter_args, **filter_kwargs)
except (TypeError, ValueError, ValidationError):
# 这里就获取到了_get_object_or_404中抛出异常, 由Http404实例化类实例化出来的对象返回到上一层
raise Http404
拓展: 修改必须使用pk作为有名分组!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
本质就是通过get将传过来的字段拆散, 以关键字的形式获取对应的数据对象
因此在自定义的视图类中重写 lookup_url_kwarg 就可以实现, 修改路由中, 对应的又名分组必须取名是pk了.
例如: 有名分组是(?P<num>), 关键字必须num接受
那么self.kwargs在给视图对象中方法传参的时候就是{'num': param}而,
self.kwargs[lookup_url_kwarg]这一步操作直接获取到的就是param了.
'''
obj = get_object_or_404(queryset, **filter_kwargs)
# 5) 这一步是APIView中dispatch方法中定义的三段认证中的权限认证. 在drf的认证中会讲到
self.check_object_permissions(self.request, obj)
return obj
5) urls.py
from django.conf.urls import url
from .views import BookListCrateView
from .views import BookUpdateDestroyRetrieve
urlpatterns = [
url(r'^books/$', BookListCrateView.as_view()),
url(r'^books/(?P<www>\d+)', BookUpdateDestroyRetrieve.as_view()),
]
6) 总结
1. 继承GenericAPIView的视图类, 当需要修改接口指定操作的模型类, 以及序列化的模型类直接在视图类中修改即可了.其他都不用动就可以实现偷换模型类以及序列化类
2. GenericAPIView提供了3个主要的方法
self.get_object() 获取单条数据
self.get_queryset() 获取多条数据
self.serializer_classes(参数同原来即可) 执行自定义视图类中定义的序列化类进行序列化, 将ORM对象的数据转换成python的对象
3. GenericAPIView提供了可修改路由又名分组的指定不再是默认的pk
自定义的视图类
三. 五个视图扩展类
1) models.py
from django.db import models
# Create your models here.
class Book(models.Model):
name = models.CharField(max_length=32)
price = models.DecimalField(max_digits=8, decimal_places=2)
author = models.CharField(max_length=32)
# 这里的定义可以让序列化类中当作序列化字段来处理, return的结果是什么就是什么.
@property
def current_time(self):
import time
return time.strftime("%Y-%m-%d %X")
publish = models.ForeignKey(to='Publish')
class Publish(models.Model):
name = models.CharField(max_length=32)
email = models.EmailField()
2) serializer.py 自定义序列化.py文件
from rest_framework import serializers
from .models import Book
from .models import Publish
class PublishModelSerializer(serializers.ModelSerializer):
class Meta:
model = Publish
fields = '__all__'
class BookModelSerializer(serializers.ModelSerializer):
publish = PublishModelSerializer()
'''
publish = serializers.SerializerMethodField(read_only=True, source='publish')
# publish = serializers.CharField()
def get_publish(self, instance):
print('instance:', instance)
fields_list = ['name', 'email']
fields_dict = {}
for field in fields_list:
if hasattr(instance.publish, field):
fields_dict[field] = getattr(instance.publish, field)
return fields_dict
'''
# 这里不做任何格外的校验处理, 只是看看校验成功以后的结果
def validated_price(self, data):
# print('data:', data)
return data
# 这里也是
def validate(self, validate_data):
# print('validate validate_data:', validate_data)
return validate_data
class Meta:
model = Book
# fields = ['id', 'name', ...]
# exclude = ['id']
fields = '__all__'
extra_kwargs = {
'price': {'max_value': 10000, 'min_value': 0}
}
def create(self, validated_data):
publish_dict = validated_data.pop('publish')
publish_obj = Publish.objects.create(**dict(publish_dict))
Book.objects.create(**validated_data, publish=publish_obj)
validated_data.update({'publish': publish_dict})
return validated_data
def update(self, instance, validated_data):
print('validated_data:', validated_data)
publish_dict = validated_data.pop('publish')
Publish.objects.filter(book__pk=instance.pk).update(**publish_dict)
Book.objects.filter(pk=instance.pk).update(**validated_data)
validated_data.update({'publish': publish_dict})
return validated_data
3) views.py
from rest_framework.generics import GenericAPIView
from rest_framework.mixins import ListModelMixin, DestroyModelMixin, UpdateModelMixin, CreateModelMixin, \
RetrieveModelMixin
from .models import Book
from .serializer import BookModelSerializer
class BookCreateListView(CreateModelMixin, ListModelMixin, GenericAPIView):
queryset = Book.objects
serializer_class = BookModelSerializer
def get(self, request):
"""
list 的实现是 ListModelMixin 类中定义的 list 方法,
并在 GenericAPIView 类中定义的的方法基础之上实现查询数据的功能
"""
return self.list(request)
def post(self, request):
"""
create 的实现是 CreateModelMixin 类中定义的 create 方法,
并在 GenericAPIView 类中定义的的方法基础之上实现新增数据的功能
"""
print('request.data:', request.data)
return self.create(request)
class BookUpdateDestroyRetrieveView(RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin, GenericAPIView):
queryset = Book.objects
serializer_class = BookModelSerializer
def get(self, request, pk):
"""
retrieve 的实现是 RetrieveModelMixin 类中定义的 retrieve 方法,
并在 GenericAPIView 类中定义的的方法基础之上实现查询一条数据的功能
"""
return self.retrieve(request, pk)
def put(self, request, pk):
"""
update 的实现是 UpdateModelMixin 类中定义的 update 方法,
并在 GenericAPIView 类中定义的的方法基础之上实现更新一条数据的功能
"""
return self.update(request, pk)
def delete(self, request, pk):
"""
destroy 的实现是 DestroyModelMixin 类中定义的 destroy 方法,
并在 GenericAPIView 类中定义的的方法基础之上实现删除一条数据的功能
"""
return self.destroy(request, pk)
4) urls.py
from django.conf.urls import url
from .views import BookUpdateDestroyRetrieveView
from .views import BookCreateListView
urlpatterns = [
url(r'^books/$', BookCreateListView.as_view()),
url(r'^books/(?P<pk>\d+)', BookUpdateDestroyRetrieveView.as_view()),
]
5) 总结
提示: 以下的5种视图扩展类必须和GenericAPIView连用
ListModelMixin 内部封装了list方法, 实现了查询所有数据
CreateModelMixin 内部封装了create方法, 实现了新增数据
RetrieveModelMixin 内部封装了retrieve方法, 实现了查询一条数据
UpdateModelMixin 内部封装了update方法, 实现了更新一条数据
DestroyModelMixin 内部封装
四. GenericAPIView的9个视图子类
1) 9个GenericAPIView的视图子类快速介绍
提示: 以下都是基与对应的5种不同的视图扩展类ModelMixin和GenericAPiView. 在原来的基础之上剔除了对应的上一个节需要定义的重复的方法
CreateAPIView
DestroyAPIView
UpdateAPIView
ListAPIView
RetrieveAPIView
ListCreateAPIView
RetrieveDestroyAPIView
RetrieveUpdateDestroyAPIView
RetrieveUpdateAPIView
2) views.py
from rest_framework.generics import GenericAPIView, \
CreateAPIView, DestroyAPIView, UpdateAPIView, ListAPIView, RetrieveAPIView, \
ListCreateAPIView, RetrieveDestroyAPIView, RetrieveUpdateDestroyAPIView, RetrieveUpdateAPIView
class BookListCreateAPIView(ListCreateAPIView):
queryset = Book
serializer_class = BookModelSerializer
class BookRetrieveUpdateDestroyAPIView(RetrieveUpdateDestroyAPIView):
queryset = Book
serializer_class = BookModelSerializer
3) urls.py
from django.conf.urls import url
from . import views
urlpatterns = [
url(r'^books/$', views.BookModelViewSet.as_view(actions={'get': 'list',})),
url(r'^books/(?P<pk>\d+)',
views.BookModelViewSet.as_view(actions={'get': 'retrieve', 'put': 'update',})),
]
五. ViewSetMixin
1) views.py
from rest_framework.viewsets import ViewSetMixin
class Book6View(ViewSetMixin,APIView): #一定要放在APIVIew前
def get_all_book(self,request):
print("xxxx")
book_list = Book.objects.all()
book_ser = BookSerializer(book_list, many=True)
return Response(book_ser.data)
2) urls.py
# 继承ViewSetMixin的视图类，路由可以改写成这样
path('books6/', views.Book6View.as_view(actions={'get': 'get_all_book'})),
3) 总结
只要是基础 ViewSetMixin 的类都可以修改视图类中方法的调用名
六. ModelViewSet
1) views.py
Copyfrom rest_framework.viewsets import ModelViewSet, ViewSetMixin, GenericViewSet, ViewSet, ReadOnlyModelViewSet
class BookModelViewSet(ModelViewSet):
queryset = Book.objects
serializer_class = BookModelSerializer
# ModelViewSet -> GenericViewSet -> ViewSetMixin 因此继承了ModelViewSet的视图类, 也可以在视图类中自定义方法, 只是路由中指定的要一致
def get_all(self, request):
return self.list(request)
2) urls.py
from django.conf.urls import url
from . import views
urlpatterns = [
url(r'^books/$', views.BookModelViewSet.as_view(actions={'get': 'get_all', 'post': 'create'})),
url(r'^books/(?P<pk>\d+)',
views.BookModelViewSet.as_view(actions={'get': 'retrieve', 'put': 'update', 'delete': 'destroy'})),
]
3) 其他viewsets中的类
1. GenericViewSet(
ViewSetMixin, generics.GenericAPIView
)
2. ViewSet(
ViewSetMixin, views.APIView
)
3. ReadOnlyModelViewSet(
mixins.RetrieveModelMixin,
mixins.ListModelMixin,
GenericViewSet
)
4) 总结
介绍: ModelViewSet继承关系非常多, 通过一层层的继承, 只需要很少的代码就能实现API的5中视图接口
它, 还可以和路由组件使用, 这样就直接使用路由直接生成对应功能的路由接口, 以及在不指定路由的基础之上默认帮我们书写了路由中在as_view()类方法中添加的actions参数了
庞大的继承可实现的功能:
1. APIView提供的
request封装
三段认证
全局异常处理
response响应格式
2. GenericAPIView提供的
视图类中声明queryset 和 serializer_classes 类属性
self.get_object ()
self.get_queryset()
self.get_serializer()
3. 五个基本视图扩展类ModelMixin系列提供的
self.list()
self.create()
self.update()
self.retrieve()
self.destroy()
4. ViewSetMixin提供的
修改路由中ac_view()类方法的actions参数
如:
路由配置: url(r'index/', BookView.as_view(actions={'get': 'get_list'}))
视图使用:
class BookView(ViewSetMixin, APIView):
def get_list(self, request):
...
七. 继承关系流程图
