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Django框架的使用教程--类视图-中间间-模板[六]

2018-07-06 01:19:05来源：博客园阅读 ()

类视图

类视图的使用

视图函数

class class_view(View):
    """类视图"""

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

    def post(self, request):
        return render(request, 'show.html')

路由

url(r'^class_view/$', views.class_view.as_view()),

结果

类视图的源码

    @classonlymethod
    def as_view(cls, **initkwargs):
        """
        Main entry point for a request-response process.
        """
        for key in initkwargs:
            if key in cls.http_method_names:
                raise TypeError("You tried to pass in the %s method name as a "
                                "keyword argument to %s(). Don't do that."
                                % (key, cls.__name__))
            if not hasattr(cls, key):
                raise TypeError("%s() received an invalid keyword %r. as_view "
                                "only accepts arguments that are already "
                                "attributes of the class." % (cls.__name__, key))
　　　　　# 类视图的函数
        def view(request, *args, **kwargs):
            self = cls(**initkwargs)
            if hasattr(self, 'get') and not hasattr(self, 'head'):
                self.head = self.get
            self.request = request
            self.args = args
            self.kwargs = kwargs
            return self.dispatch(request, *args, **kwargs)
        view.view_class = cls
        view.view_initkwargs = initkwargs

        # take name and docstring from class
        update_wrapper(view, cls, updated=())

        # and possible attributes set by decorators
        # like csrf_exempt from dispatch
        update_wrapper(view, cls.dispatch, assigned=())
        return view
　　　　# 根据不同的请求函数返回不同的值
    def dispatch(self, request, *args, **kwargs):
        # 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)
        else:
            handler = self.http_method_not_allowed
        return handler(request, *args, **kwargs)

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

类视图使用装饰器

方法一:使用装饰器定义类视图(不推荐使用,只能整个类添加装饰器,不能单独方法添加)

代码

def my_decorator(func):
    def without(request, *args, **kwargs):
        print('装饰器被调用')
        print('路径%s' % request.path)
        return func(request, *args, **kwargs)

    return without


class decorator_view(View):
    def get(self, request):
        print('这是get方法')
        return HttpResponse('ok')

    def post(self, request):
        print('这是post方法')
        return HttpResponse('ok')

路由

# 直接在URL中使用装饰器
from .views import decorator_view
url(r'^decorator_view/$', views.my_decorator(decorator_view.as_view())),

结果

方法二:使用装饰器定义类视图(可以指定的请求方式)

代码(以下的视图函数名字可以自己定义过)

# 可以指定装饰器的特定请求，如name='get'
@method_decorator(my_decorator, name='dispatch')
class decorator_view(View):
    def get(self, request):
        print('这是get方法')
        return HttpResponse('ok')

    def post(self, request):
        print('这是post方法')
        return HttpResponse('ok')

路由

# 直接在URL中使用装饰器
from .views import decorator_view
url(r'^decorator_view/$', views.my_decorator(decorator_view.as_view())),

运行结果

方法三:使用装饰器定义类视图(定义方法的类装饰器)

代码

class decorator_view(View):
    # 给get添加装饰器
    @method_decorator(my_decorator)
    def get(self, request):
        print('这是get方法')
        return HttpResponse('ok')

    # 给post添加装饰器
    @method_decorator(my_decorator)
    def post(self, request):
        print('这是post方法')
        return HttpResponse('ok')

路由

# 直接在URL中使用装饰器
from .views import decorator_view
url(r'^decorator_view/$', views.my_decorator(decorator_view.as_view())),

运行(postman测试)

中间件

在子应用工程目录中新建一个middleware.py文件

middleware.py(在调试模式下,中间件被调用两次)

def my_middleware(get_response):
    print('__init__初始化')

    def in_middleware(request):
        print('请求之前被调用')
        response = get_response(request)
        print('请求之后被调用')
        return response

    return in_middleware

视图函数

def index_view(request):
    print('view视图被调用')
    return HttpResponse('ok')

运行

注册中间件

多个中间件的使用

1)在视图函数执行之前,中间件由上至下执行

2)在视图函数请求至后,中间间由下到上

注册中间间

定义两个中间件

def my_middleware(get_response):
    print('__init__初始化')

    def in_middleware(request):
        print('请求之前被调用')
        response = get_response(request)
        print('请求之后被调用')
        return response

    return in_middleware


def my_middleware1(get_response):
    print('__init2__初始化')

    def in_middleware(request):
        print('请求2之间被调用')
        response = get_response(request)
        print('请求2之后被调用')
        return response
    return in_middleware