Django之FBV / CBV和中間件

FBV / CBV 

FBV：function base view

 url(r'^index$',user)

路由

def users(request):
    return HttpResponse(‘OK’)

視圖

CBV：class base view

url(r'^students/', views.StudentsView.as_view())

路由

from django.views import View

class StudentsView(View):

    def get(self,request,*args,**kwargs):
    return HttpResponse('GET')

    def post(self, request, *args, **kwargs):
    return HttpResponse('POST')

    def put(self, request, *args, **kwargs):
    return HttpResponse('PUT')

    def delete(self, request, *args, **kwargs):
    return HttpResponse('DELETE')

視圖

CBV實現原理

　　基於反射實現根據請求方式不一樣，執行不一樣的方法。具體實現流程：url中的as_view() —》 view方法 —》 dispatch方法（根據反射執行相應函數）

CBV中可使用的方法：

 http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace']

from django.views import View
class RestApi(View):
    def dispatch(self,request,*args,**kwargs):
        func = getattr(self,request.method.lower())
        ret = func(request,*args,**kwargs)
        return ret

    def get(self,request,*args,**kwargs):
        return HttpResponse('get')

    def post(self,request,*args,**kwargs):
        return HttpResponse('post')

    def put(self,request,*args,**kwargs):
        return HttpResponse('put')

    def delete(self,request,*args,**kwargs):
        return HttpResponse('delete')

手動實現dispatch方法

from django.views import View
class RestApi(View):
    def dispatch(self,request,*args,**kwargs):
        ret = super(RestApi, self).dispatch(request,*args,**kwargs)
        return ret

    def get(self,request,*args,**kwargs):
        return HttpResponse('get')

    def post(self,request,*args,**kwargs):
        return HttpResponse('post')

    def put(self,request,*args,**kwargs):
        return HttpResponse('put')

    def delete(self,request,*args,**kwargs):
        return HttpResponse('delete')

手動繼承dispatch方法

Django中間件

　　django 中的中間件（middleware），在django中，中間件其實就是一個類，在請求到來和結束後，django會根據本身的規則在合適的時機執行中間件中相應的方法。

咱們從瀏覽器發出一個請求 Request，獲得一個響應後的內容 HttpResponse ，這個請求傳遞到 Django的過程以下：

　　每個請求都是先經過中間件中的 process_request 函數，這個函數返回 None 或者 HttpResponse 對象，若是返回前者，繼續處理其它中間件，若是返回一個 HttpResponse，就處理停止，返回到網頁上。

中間件中能夠定義4個方法,分別是:

1. process_request(self,request) 發送請求
2. process_view(self, request, callback, callback_args, callback_kwargs) 執行完 request 預處理函數並肯定待執行的 view 以後，但在 view 函數實際執行以前。
3. process_template_response(self,request,response)
4. process_exception(self, request, exception) 收集錯誤信息
5. process_response(self, request, response) 必須返回 HttpResponse 對象. 這個 response 對象能夠是傳入函數的那一個原始對象（一般已被修改），也能夠是全新生成的。

執行順序也是按照以上順序執行的.

自定義中間件

from django.utils.deprecation import MiddlewareMixin

class test1(MiddlewareMixin):
    def process_request(self, request):
        print('wusir')

class test2(MiddlewareMixin):
    def process_request(self, request):
        print('jack')

View Code

註冊中間件

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'wusir.m1.test1',
    'wusir.m1.test2',
]

View Code

終端輸出結果

wusir
jack
tom
[17/Dec/2018 17:08:04] "GET /app/aa HTTP/1.1" 200 2

View Code

PS:與mange.py在同一目錄下的文件夾 wusir下的m1.py文件中的test1,test2類

中間件能夠作什麼

• 　　權限
• 　　用戶登陸驗證
• 　　Django的csrf的實現

狀況一：
MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware', # 全站使用csrf認證
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]


from django.views.decorators.csrf import csrf_exempt
@csrf_exempt # 該函數無需認證
def users(request):
    user_list = ['alex','oldboy']
    return HttpResponse(json.dumps((user_list)))

狀況二：
MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    #'django.middleware.csrf.CsrfViewMiddleware', # 全站不使用csrf認證
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]


from django.views.decorators.csrf import csrf_exempt
@csrf_protect # 該函數需認證
def users(request):
    user_list = ['alex','oldboy']
    return HttpResponse(json.dumps((user_list)))

爲某個函數單獨增長或取消CSRF認證

CSRF在CBV中的使用補充
　　裝飾器@csrf_exempt，@csrf_protect必須在dispatch方法中（單獨方法無效）

方式一：
    from django.views.decorators.csrf import csrf_exempt,csrf_protect
    from django.utils.decorators import method_decorator
    class StudentsView(View):
        
        @method_decorator(csrf_exempt)
        def dispatch(self, request, *args, **kwargs):
            return super(StudentsView,self).dispatch(request, *args, **kwargs)

        def get(self,request,*args,**kwargs):
            print('get方法')
            return HttpResponse('GET')

        def post(self, request, *args, **kwargs):
            return HttpResponse('POST')

        def put(self, request, *args, **kwargs):
            return HttpResponse('PUT')

        def delete(self, request, *args, **kwargs):
            return HttpResponse('DELETE')
方式二：
    from django.views.decorators.csrf import csrf_exempt,csrf_protect
    from django.utils.decorators import method_decorator

    @method_decorator(csrf_exempt,name='dispatch')
    class StudentsView(View):

        def get(self,request,*args,**kwargs):
            print('get方法')
            return HttpResponse('GET')

        def post(self, request, *args, **kwargs):
            return HttpResponse('POST')

        def put(self, request, *args, **kwargs):
            return HttpResponse('PUT')

        def delete(self, request, *args, **kwargs):
            return HttpResponse('DELETE')

View Code