drf source code analysis and global catch exception

Python之drfSource code analysis and global catch exceptions

一、认证源码分析

views.pyUsed within the authentication class,Custom authentication class with file

# authentication.py
from rest_framework.authentication import BaseAuthentication
# Inherit the authentication base classBaseAuthentication
class bookAuthentication(BaseAuthentication):
    # 重写authenticate方法
    def authenticate(self,request):
       token =  request.GET.get('token')
       user_token = UserToken.objects.filter(token=token).first()
        if user_token:
            # 带的token是有效的
            # user_token.user当前登录用户
            return user_token.user, token
        else:
            raise AuthenticationFailed('token不合法或没有迭代token')
            
# views.py
from .serializers import Bookserializers
from .models import Book
from rest_framework.generics import ListCreateAPIView
from .authentication import bookAuthentication

class BookListCreateAPIView(ListCreateAPIView):
    queryset = Book.objects.all()
    serializer_class = Bookserializers
    authentication_classes = [bookAuthentication,]

源码分析

#1 入口---》APIView的dispatch---》self.initial(request, *args, **kwargs)————》The code for the authentication classself.perform_authentication(request)

# 2 self.perform_authentication(request)
    def perform_authentication(self, request):
        request.user # 新的request对象的user方法
        
# 2 Request类的user方法
    @property
    def user(self):
        if not hasattr(self, '_user'):
            with wrap_attributeerrors():
                self._authenticate()  # 核心就是这句话,是Request的
        return self._user
    
    
# 3 Request类的_authenticate(self)方法
    def _authenticate(self):
        for authenticator in self.authenticators: #self.authenticators是个列表,An object of the authentication class is placed in the list
            try:
                # self是request,So our authentication classauthenticate,有两个参数,selfThe second parameter is given
                user_auth_tuple = authenticator.authenticate(self) # 执行认证类的authenticate方法
            except exceptions.APIException:
                self._not_authenticated()
                raise

            if user_auth_tuple is not None:
                self._authenticator = authenticator
                self.user, self.auth = user_auth_tuple  #解压赋值,后续的requtst对象就有user属性了
                return

        self._not_authenticated()
        
 
# 4 Request类的self.authenticators属性
	-是在Request初始化的时候,传入的
    -RequestWhen is the class initialized---》APIView的dispatchstarting position in 
    -APIView的dispatch---》request = self.initialize_request(request, *args, **kwargs)

    
# 5 APIView的self.initialize_request方法
	def initialize_request(self, request, *args, **kwargs):
        return Request(
            request,
            parsers=self.get_parsers(),
            authenticators=self.get_authenticators(),# APIView
            negotiator=self.get_content_negotiator(),
            parser_context=parser_context
        )
    
# 6 APIView的get_authenticators
    def get_authenticators(self):
        # An object of the authentication class is placed in the list
        return [auth() for auth in self.authentication_classes]

二、权限源码分析

#1 入口---》APIView的dispatch---》Permission class codeself.check_permissions(request)

#2 APIView的check_permissions(request)方法
    def check_permissions(self, request):
        for permission in self.get_permissions():
            if not permission.has_permission(request, self):
                self.permission_denied(
                    request,
                    message=getattr(permission, 'message', None),
                    code=getattr(permission, 'code', None)
                )
#3 APIView的self.get_permissions():
    def get_permissions(self):
        # There are objects of the permission class in the list
        return [permission() for permission in self.permission_classes]
    
# 4 权限认证失败,返回中文
	-Configured in the permission classmessage即可（给对象,类都可以）

三、频率源码分析

#1 入口---》APIView的dispatch---》The code for the frequency classself.check_throttles(request)

# 2 APIView的self.check_throttles(request)
    def check_throttles(self, request):
        throttle_durations = []
        for throttle in self.get_throttles():# #列表,It is an object of the frequency class configured in each view class
            if not throttle.allow_request(request, self):
                throttle_durations.append(throttle.wait())
                
# 3 APIView的self.get_throttles()
       def get_throttles(self):
        return [throttle() for throttle in self.throttle_classes]

四、Filter source code analysis

from rest_framework.generics import GenericAPIView,ListAPIView
from rest_framework.mixins import ListModelMixin

class Book(ListAPIView):
    filter_backends = ['过滤类']


首先要明确一点,The filter query is to query all the data that meet the conditions
So the view layer must inheritGenericAPIView和ListModelmixin.也就是ListAPIView

ListModelmixin里有list方法————>方法里有queryset = self.filter_queryset(self.get_queryset())This is where the query bar is filtered.self.get_queryset()取出所有数据,然后调用filter_queryset方法进行过滤

在视图类GenericAPIView中有filter_queryset：
	    def filter_queryset(self, queryset):
            for backend in list(self.filter_backends): # Go to the view layer to find itfilter_backends
            Find its filter class and add parentheses to call the overridden under itfilter_queryset方法
                queryset = backend().filter_queryset(self.request, queryset, self) 
            return queryset

个人理解：
如果你使用rest_framework.filter中的SearchFilterFor filtering then your code in the view layer will be like this:
    from rest_framework.filters import SearchFilter
    from rest_framework.generics import GenericAPIView,ListAPIView
    from rest_framework.mixins import ListModelMixin

    class Book(ListAPIView):
        filter_backends = [SearchFilter,]
在其GenericAPIView源码中：视图类GenericAPIView中的filter_queryset方法下的backend().filter_queryset(self.request, queryset, self)就变成了SearchFilter().filter_queryset(self.request, queryset, self)
而SearchFilter().filter_queryset(self.request, queryset, self),Internal filtering is performedSearchFilter()类的filter_queryset()方法.

If you need to customize the filter class, you need to inherit the filter base classBaseFilterBackend,重写BaseFilterBackend类下的filter_queryset()方法
The execution flow of internal source code is the same

五、Paging source code analysis

Pagination is to page through all the data,So the view layer must inheritGenericAPIView和ListModelmixin.也就是ListAPIView
from rest_framework.generics import GenericAPIView,ListAPIView
from rest_framework.mixins import ListModelMixin

class Book(ListAPIView):
    pagination_class =['分页类']
    
ListModelmixin里有list方法————>方法里有：
	page = self.paginate_queryset(queryset) # 执行分页
    if page is not None:
        serializer = self.get_serializer(page, many=True) # Serialize the current paginated data
        return self.get_paginated_response(serializer.data) # Returns the previous and next pages and the total number of entries
在视图类GenericAPIView中有paginate_queryset：
	   if self.paginator is None: # self.paginatorIt is an object of the paging class
            return None
        # 实现了分页功能,取出从前端地址中传入的,第几页,取多少条
    	# 在该方法中自动实现分页,返回当前页码的数据
        return self.paginator.paginate_queryset(queryset, self.request, view=self)
在视图类GenericAPIView中有get_paginated_response：
	# self.paginatorIt is an object of the paging class
	return self.paginator.get_paginated_response(data)

Combining personal understandingPageNumberPagination：
如果你使用rest_framework.pagination中PageNumberPagination来进行分页,Your code in the view layer will look like this：
	from rest_framework.pagination import PageNumberPagination,LimitOffsetPagination,CursorPagination
    from rest_framework.generics import GenericAPIView,ListAPIView
    from rest_framework.mixins import ListModelMixin

    class Book(ListAPIView):
        pagination_class =[PageNumberPagination,]
在其GenericAPIView源码中self.paginate_queryset(queryset)就会变成paginate_queryset(self, queryset)下的
return PageNumberPagination.paginate_queryset(queryset, self.request, view=self)
而get_paginated_response下的self.paginator.get_paginated_response(data)会变成PageNumberPagination.paginate_queryset(queryset, self.request, view=self)

继承APIView实现分页

# 首先需要新建一个pyThe file is written on an inheritancePageNumberPagination的类,And modify the class properties inside as follows：
papg.py
from rest_framework.pagination import PageNumberPagination
class bookPageNumberPagination(PageNumberPagination):
    page_size = 5
    page_query_param = 'page'
    page_size_query_param = 'size'
    max_page_size = 10
   
# 在viewsWrite code in the view class：
from rest_framework.virews import APIView
from .papg import bookPageNumberPagination
from .models import Book
from .serializers import BookserializersModelserializer
from rest_framework.response import Response
class book(APIView):
    def get(self,request):
        # Get all the data
        all_book_queryset = Book.objcets.all()
        # Instantiate an object of the paging class
        page = bookPageNumberPagination()
        # Calls the class inherited from its paging classPageNumberPagination中的paginate_queryset方法,And pass all the data into the method
        res= page.paginate_queryset(all_book_queryset,request,self)
        # Serialize the data in the pagination class
        serializer = BookserializersModelserializer(res, many=True)
        # 将data返回出去
        return Response(serializer.data)/page.get_paginated_response(serializer.data)

六、Custom global catch exception

from rest_framework.views import exception_handler
from rest_framework.response import Response

# 自定义异常处理
def common_exceptions_handler(exc, context):
    response_exceptions = exception_handler(exc,context)
    user_id = context.get('request').user.id
    if not user_id:
        user_id = '用户未登录'
    # Precise positioning is abnormal,It is convenient to write to the log later
    errors_detail = '视图类:%s出错了,访问者的ip为:%s,访问者的id为:%s,错误原因为:%s'%(
        str(context.get('view')),
        context.get('request').META.get('REMOTE_ADDR'),
        user_id,
        str(exc)
        )
    print(errors_detail)

    dic = {
    'code':999,'msg':''}
    # 如果response_exceptionsA value indicates that the exception is presentexceptions_handler中的Http404、PermissionDenied、exceptions.APIException,异常中
    if response_exceptions:
        dic['msg'] = response_exceptions.data
        return Response(dic)
    # No value description is other exception
    dic['msg'] = '服务器异常'
    return Response(dic)

""" 注意： 自定义异常必须继承APIView及其子类,因为exception_handler()方法就是APIView下的 """

全局配置

REST_FRAMEWORK = {
    
    # Path to custom exception
    'EXCEPTION_HANDLER':'appo1.lib.execption.common_exceptions_handler',
}

七、coreapi自动生成接口文档

# front and rear separation
	-A group of people at the front
    	-No idea what interface you wrote,What are the request parameters,What is the response data like
        -I don't know what encoding to use
    -A group of people at the back end
    	-We wrote a lot of interfaces
        
        
# 需要写接口文档（Different companies have specifications）
	-1 The company has an interface documentation platform,The backend enters the interface on the platform
    -2 Use a third-party interface documentation platform,The back-end is written in the platform entry
    	-Yapi:开源
    -3 使用md,word文档写,write togit上
    -4 自动生成接口文档（swagger,coreapi）
    	-swagger自动导入,导入到Yapi中

        
# coreapi
	-pip3 install coreapi
    -在路由中配置
    from rest_framework.documentation import include_docs_urls
    path('docs/', include_docs_urls(title='Luffy project interface documentation platform'))
    -在配置文件中配置
    	REST_FRAMEWORK = {
    
    	'DEFAULT_SCHEMA_CLASS': 'rest_framework.schemas.coreapi.AutoSchema',
}
    
    -访问地址http://127.0.0.1:8000/docs（As long as there are routes,都能看到）