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django 视图函数

[toc]

3.视图函数​

3.1 request对象​

request.path  	#request.path当前请求路径
request.method 	#当前请求方法(get,post...)
request.GET 		#获取所有get请求携带过来的数据
request.POST 		#获取所有post请求携带过来的数据
request.body 		#获取所有post请求携带过来的数据的原始格式

3.2 视图函数使用小示例​

urls文件

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    #编写一个login登陆视图文件
    url(r'^login/', views.login),

]

views文件

from django.shortcuts import render,HttpResponse
def login(request):
    if request.method == 'GET':
        return render(request,'login.html')
    else:
        uname = request.POST.get('username')
        pwd = request.POST.get('password')

        if uname == 'admin' and pwd == 'admin':
            return HttpResponse('登陆成功！')
        else:
            return HttpResponse('登陆失败!!!')

html文件

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="" method="post">
{#<form action="">#}
    用户名：<input type="text" name="username">
    密码：<input type="password" name="password">
    <input type="submit" value="登陆">
</form>

</body>
</html>

为了验证post请求，注释settings文件中的一行

Django项目下同名目录中的settings文件，48行
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',
]

浏览器访问

login1

错误的示例​

urls文件

def login(request):
    if request.method == 'POST':
        return render(request,'login.html')
    else:
        uname = request.GET.get('username')
        pwd = request.GET.get('password')

        if uname == 'admin' and pwd == 'admin':
            return HttpResponse('登陆成功！')
        else:
            return HttpResponse('登陆失败!!!')

html文件

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
{#<这里指定提交请求方法为post>#}  
<form action="" method="post">
    用户名：<input type="text" name="username">
    密码：<input type="password" name="password">
    <input type="submit" value="登陆">
</form>

</body>
</html>

为了验证post请求，注释settings文件中的一行

Django项目下同名目录中的settings文件，48行
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',
]

按照之前的理解应该是会返回登陆界面，因为我login.html文件中form表单写的请求方法是post，而views视图文件中的逻辑判断是如果请求是post则返回登陆界面，但是实际情况并不是这样

iShot_2024-08-29_19.27.05

为什么会直接返回登陆失败呢？

原因：当浏览器打开页面的时候，默认的方法就是GET，当点击登陆那一刻才会根据form表单中的method指定的请求类型而进行转变，但是现在直接就是GET方法，因此在login函数的判断中就直接跳到了第一个else后面，但是此时根本就没有用户登陆界面出现，所以就无法获取用户名和密码，所以会直接提示登陆失败！！！

3.3 响应方法​

  • render返回html页面
  • HttpResponse返回字符串
  • redirect

3.3.1render 返回html页面​

views文件中的写法

#需要导入HttpResponse
from django.shortcuts import render,HttpResponse

# Create your views here.

def index(request):
    return render(request,'index.html')

3.3.2 HttpResponse 返回字符串​

views文件中的写法

#需要导入HttpResponse
from django.shortcuts import render,HttpResponse

# Create your views here.

#HttpResponse方法中直接写字符串
def index(request):
    # return render(request,'index.html')
    return HttpResponse('HttpResponse方法返回的是字符串')

iShot_2024-08-29_19.29.06

3.3.3 redirect 重定向​

FBV写法​

urls文件

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^home/', views.home),
    url(r'^login/', views.login),
]

views文件

#redirect方法需要导入redirect
from django.shortcuts import render,HttpResponse,redirect
# Create your views here.

def home(request):

    return HttpResponse('登陆成功')


def login(request):
    if request.method == 'GET':
        return render(request,'login.html')
    else:
        uname = request.POST.get('uname')
        pwd = request.POST.get('pwd')

        if uname == 'admin' and pwd == 'admin':
            # return HttpResponse('登陆成功')
            return redirect('/home/')
        else:
            # return HttpResponse('登陆失败')
            return redirect('/login/')

redict是重定向，之前我们访问的时候如果登陆失败就直接提示登陆失败
现在使用了redict重定向
	如果登陆成功就重定向到另一个路径下，这里是/home，也就是登陆成功页面
  如果登陆失败就还是重定向到访问路径下，这里是/login，也就是登陆界面
CBV写法​

urls文件

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    # url(r'^login/', views.login),
    url(r'^login/', views.LoginView.as_view()),
]

views文件

#redirect方法需要导入redirect
from django.shortcuts import render,HttpResponse,redirect
from django.views import View   #CBV写法中需要导入View
# Create your views here.

def home(request):

    return HttpResponse('登陆成功')

class LoginView(View):
    def get(self,request):
        return render(request, 'login.html')

    def post(self,request):
        uname = request.POST.get('username')
        pwd = request.POST.get('password')

        if uname == 'admin' and pwd == 'admin':
            # return HttpResponse('登陆成功')
            return redirect('/home/')
        else:
            # return HttpResponse('登陆失败')
            return redirect('/login/')
          
          
redict是重定向，之前我们访问的时候如果登陆失败就直接提示登陆失败
现在使用了redict重定向
	如果登陆成功就重定向到另一个路径下，这里是/home，也就是登陆成功页面
  如果登陆失败就还是重定向到访问路径下，这里是/login，也就是登陆界面

3.4 CBV和FBV​

3.4.1含义​

  • FBV:function based view :基于函数的视图逻辑
  • CBV:class based view :基于类的视图逻辑

3.4.2 CBV​

CBV中url写法

 # url(r'^login/', views.login),
 url(r'^login/', views.LoginView.as_view()),

CBV中views写法

from django.shortcuts import render,HttpResponse,redirect
from django.views import View   #CBV写法中需要导入View
# Create your views here.

class LoginView(View):
    def get(self,request):
        return render(request, 'login.html')

    def post(self,request):
        uname = request.POST.get('username')
        pwd = request.POST.get('password')

        if uname == 'admin' and pwd == 'admin':
            # return HttpResponse('登陆成功')
            return redirect('/home/')
        else:
            # return HttpResponse('登陆失败')
            return redirect('/login/')

CBV中源码重点

    def dispatch(self, request, *args, **kwargs):  #根据请求方法去分发对应的类发放来执行
        # Try to dispatch to the right method; if a method doesn't exist,
        # defer to the error handler. Also defer to the error handler if the
        # request method isn't on the approved list.
        if request.method.lower() in self.http_method_names:  
            handler = getattr(self, request.method.lower(), self.http_method_not_allowed)  #反射!!!!
        else:
            handler = self.http_method_not_allowed
        return handler(request, *args, **kwargs)

CBV中重写dispatch方法

class LoginView(View):
    def dispatch(self, request, *args, **kwargs):
        print(111)
        # print(request.META)  #http所有相关请求头信息
        ret = super().dispatch(request, *args, **kwargs) #render(request, 'login.html')
        print(222)
        return ret
    def get(self,request):
        print('this is get method!!!')
        return render(request, 'login.html')
    def post(self,request):
        uname = request.POST.get('username')
        pwd = request.POST.get('password')
        if uname == 'admin' and pwd == 'admin':
            return redirect('/home/')
        else:
            return redirect('/login/')

3.4.3 FBV​

FBV中url写法

url(r'^login/', views.login),
#url(r'^login/', views.LoginView.as_view()),

FBV中views写法

from django.shortcuts import render,HttpResponse,redirect
# Create your views here.

def login(request):
    if request.method == 'GET':
        return render(request,'login.html')
    else:
        uname = request.POST.get('uname')
        pwd = request.POST.get('pwd')

        if uname == 'admin' and pwd == 'admin':
            # return HttpResponse('登陆成功')
            return redirect('/home/')
        else:
            # return HttpResponse('登陆失败')
            return redirect('/login/')

3.4.4 CBV和FBV的装饰器​

def func(f):
    def foo(request):
        print(111)
        ret = f(request)
        print(222)
        return ret
    return foo


#FBV 模式下,和普通函数加装饰器是一样的写法
    @func   
    def home(request):
        print('home')
        return HttpResponse('你懂什么是装饰器吗？')
    
    
CBV加装饰的三个姿势:
    # @method_decorator(func,name='get') 位置3
    class LoginView(View):
        # @method_decorator(func) #位置2
        def dispatch(self, request, *args, **kwargs):
            print('aaaa')
            ret = super().dispatch(request, *args, **kwargs) #render(request, 'login.html')
            print('bbbb')
            return ret
        @method_decorator(func)  #位置1
        def get(self,request):
            print('this is get method!!!')
            return render(request, 'login.html')

        def post(self,request):
            uname = request.POST.get('username')
            pwd = request.POST.get('password')
            if uname == 'admin' and pwd == 'admin':
                return redirect('/home/')
            else:
                return redirect('/login/')
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