restframework安装及APIView分析

一、restframework的安装

方式一：pip3 install djangorestframework

方式二：pycharm图形化界面安装

方式三：pycharm命令行下安装（装在当前工程所用的解释器下）

二、基于Django实现的API(不带restframework)

FBV

 from django.shortcuts import render,HttpResponse
 
 # Create your views here.
 import json
 
 def users(request):
     response = {'code':1000,'data':None}  #code用来表示状态，比如1000代表成功，1001代表
     response['data'] = [
         {'name':'haiyan','age':22},
         {'name':'haidong','age':10},
         {'name':'haixiyu','age':11},
     ]
     return HttpResponse(json.dumps(response))  #返回多条数据
 
 def user(request,pk):
     if request.method =='GET':
         return HttpResponse(json.dumps({'name':'haiyan','age':11}))  #返回一条数据
     elif request.method =='POST':
         return HttpResponse(json.dumps({'code':1111}))  #返回一条数据
     elif request.method =='PUT':
         pass
     elif request.method =='DELETE':
         pass
 
 views

CBV

from django.views import View
class UsersView(View):
    def get(self,request):
        response = {'code':1000,'data':None}
        response['data'] = [
            {'name': 'haiyan', 'age': 22},
            {'name': 'haidong', 'age': 10},
            {'name': 'haixiyu', 'age': 11},
        ]
        return HttpResponse(json.dumps(response),stutas=200)
 
class UserView(View):
    def get(self,request,pk):
        return HttpResponse(json.dumps({'name':'haiyan','age':11}))  #返回一条数据
    def post(self,request,pk):
        return HttpResponse(json.dumps({'code':1111}))  #返回一条数据
    def put(self,request,pk):
        pass
    def delete(self,request,pk):
        pass
 
views

三、restframework里封装的APIView分析

基于django实现的API许多功能都需要我们自己开发，这时候djangorestframework就给我们提供了方便，直接基于它来返回数据，总之原理都是一样的，就是给一个接口也就是url，让前端的人去请求这个url去获取数据，在页面上显示出来。这样也就达到了前后端分离的效果。

as_view方法

 @classmethod
     def as_view(cls, **initkwargs):
         """
         Store the original class on the view function.
 
         This allows us to discover information about the view when we do URL
         reverse lookups.  Used for breadcrumb generation.
         """
         if isinstance(getattr(cls, 'queryset', None), models.query.QuerySet):
             def force_evaluation():
                 raise RuntimeError(
                     'Do not evaluate the `.queryset` attribute directly, '
                     'as the result will be cached and reused between requests. '
                     'Use `.all()` or call `.get_queryset()` instead.'
                 )
             cls.queryset._fetch_all = force_evaluation
 
         view = super(APIView, cls).as_view(**initkwargs)
         view.cls = cls
         view.initkwargs = initkwargs
 
         # Note: session based authentication is explicitly CSRF validated,
         # all other authentication is CSRF exempt.
         return csrf_exempt(view)
 
 as_view方法

dispatch方法

 def dispatch(self, request, *args, **kwargs):
         """
         `.dispatch()` is pretty much the same as Django's regular dispatch,
         but with extra hooks for startup, finalize, and exception handling.
         """
         self.args = args
         self.kwargs = kwargs
         request = self.initialize_request(request, *args, **kwargs)
         self.request = request
         self.headers = self.default_response_headers  # deprecate?
 
         try:
             self.initial(request, *args, **kwargs)
 
             # Get the appropriate handler method
             if request.method.lower() in self.http_method_names:
                 handler = getattr(self, request.method.lower(),
                                   self.http_method_not_allowed)
             else:
                 handler = self.http_method_not_allowed
 
             response = handler(request, *args, **kwargs)
 
         except Exception as exc:
             response = self.handle_exception(exc)
 
         self.response = self.finalize_response(request, response, *args, **kwargs)
         return self.response
 
 dispatch

initialize_request

 def initialize_request(self, request, *args, **kwargs):
         """
         Returns the initial request object.
         """
         parser_context = self.get_parser_context(request)
 
         return Request(
             request,
             parsers=self.get_parsers(),
             authenticators=self.get_authenticators(),
             negotiator=self.get_content_negotiator(),
             parser_context=parser_context
         )
 
 initialize_request

initial方法（内部调用认证，权限和频率）

 def initial(self, request, *args, **kwargs):
         """
         Runs anything that needs to occur prior to calling the method handler.
         """
         self.format_kwarg = self.get_format_suffix(**kwargs)
 
         # Perform content negotiation and store the accepted info on the request
         neg = self.perform_content_negotiation(request)
         request.accepted_renderer, request.accepted_media_type = neg
 
         # Determine the API version, if versioning is in use.
         version, scheme = self.determine_version(request, *args, **kwargs)
         request.version, request.versioning_scheme = version, scheme
 
         # Ensure that the incoming request is permitted
         self.perform_authentication(request)
         self.check_permissions(request)
         self.check_throttles(request)
 
 initial方法（内部调用认证，权限和频率）