REST-APIView源碼分析

前言:APIView基于View 看這部分內(nèi)容一定要懂django—CBV里的內(nèi)容

在django—CBV源碼分析中，我們是分析的from django.views import View下的執(zhí)行流程
這篇博客我們就來了解下APIView是如何執(zhí)行的，跟django.views模塊下的view有何關(guān)聯(lián)？
我們依然從urls.py配置入手分析

from django.conf.urls import url
from django.contrib import admin
from app01 import views

urlpatterns = [
    url(r'^publishes/', views.PublishView.as_view()),
]

views.py

from rest_framework.views import  APIView

class PublishView(APIView):

    def get(self,request):
        publish_list=Publish.objects.all()
        ret=serialize("json",publish_list)

        return HttpResponse(ret)

    def post(self,request):
        pass

1、首先我們還是來確認(rèn)urls.py中as_view是誰執(zhí)行的?
首先我們?nèi)?code>views.PublishView中找,發(fā)現(xiàn)找不到,所以我們接著再去PublishView的父類APIView中去找,找到了所以執(zhí)行調(diào)用APIView.as_view(),內(nèi)容如下:

class APIView(View):

    # 多余的代碼暫且刪掉了
    @classmethod
    def as_view(cls, **initkwargs):
        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
        
        # 1. super調(diào)用父類的as_view的執(zhí)行結(jié)果賦值給view這個(gè)變量
        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.
        
        # csrf_exempt 不在執(zhí)行調(diào)用csrf_token那個(gè)中間件
        # 中間件是針對(duì)全局的 
        # 2. 這里返回的view就是父類View.view
        return csrf_exempt(view)

2、大家是不是以為這樣就結(jié)束了?NO!NO!NO!
如果是as_view是View的as_view,dispatch是View的dispatch,那rest-framework不就成廢鈔了么?
as_view的執(zhí)行結(jié)果是dispatch的執(zhí)行結(jié)果,那么dispatch還是View的dispatch么?

1. 我們先看下views.PublishView里邊有沒有dispatch,發(fā)現(xiàn)沒有
2. 我們?cè)趘iews.PublishView的父類APIView,發(fā)現(xiàn)有
3. 所以dispatch是APIView.dispatch非View.dispatch
4. APIView.dispatch 里邊有一堆組件,這里不說

中間的這點(diǎn)代碼跟之前的View.dispatch一樣:
還是做請(qǐng)求分發(fā),在請(qǐng)求之外又做了一堆事情

    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)

總結(jié):

url 轉(zhuǎn)變過程

1. url(r'^publishes/', views.PublishView.as_view()),
2. url(r'^publishes/', APIView.as_view()),
3. url(r'^publishes/', View.as_view()),

View.as_view()我們?cè)?a href="http://www.itdecent.cn/p/dc942c470f56" target="_blank">django—CBV講解過了
所以最后調(diào)用還是,只是APIView.as_view在里邊加了一些他自己定義的一些東西,只是這里沒講到而已

APIView.as_view()---> View.as_view()---> APIView.dispatch()--->response--->handler()--> 自己定義請(qǐng)求方法函數(shù)的返回結(jié)果,否則就拋錯(cuò)405