Django-CBV和跨域请求伪造

1. django模式

def users(request):
    user_list = ['alex','oldboy']
    return HttpResponse(json.dumps((user_list)))

路由：
    url(r'^students/', views.StudentsView.as_view()),
视图： 通过发射来找到对应的方法去执行
    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')        

详谈cbv工作模式

基于反射实现根据请求的方式不同，执行不同的方法

原理

-- url -> view方法 -> dispatch方法（反射执行其他：GET/POST/DELETE/PUT）

流程

class StudentsView(View):
    def dispatch(self, request, *args, **kwargs):
    print('before')
    ret=super(StudentsView,self).dispatch(request,*args,**kwargs)
    print('after')
    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')

2. 面向对象的继承

多个类共用的功能，为了避免重复编写

from django.views import View
最左原则
class MyBaseView(object):
    def dispatch(self, request, *args, **kwargs):
        print('before')
        ret = super(MyBaseView, self).dispatch(request, *args, **kwargs)
        print('after')
        return ret


class StudentsView(MyBaseView, 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')
    

class TeachersView(MyBaseView, 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')

3. 面向对象的封装

class File:
    文件增删改查方法
                    
Class DB:
    数据库的方法

class File:
    def __init__(self,a1,a2):
        self.a1 = a1 
    self.xxx = a2
    def get:...
    def delete:...
    def update:...
    def add:...
                    
obj1 = File(123,666)   将数据123，666 封装到对象中
obj2 = File(456,999)

from django.test import TestCase

# Create your tests here.

## 封装示例

class Request(object):
    def __init__(self,obj):   # OBJ=对象B,AUTH的这个对象
        self.obj = obj

    @property        # 静态方法
    def user(self):           # REQ.USER执行这里，返回 self.obj.authticate() = self.B.authticat() = Auth.authticat() = 'JOKER'
        return self.obj.authticate()

class Auth(object):
    def __init__(self,name,age):  # NAME=JOKER,AGE=18
        self.name = name
        self.age = age

    def authticate(self):
        return self.name  # 返回类的属性NAME


class APIView(object):
    def dispatch(self):   # 方法被执行
        self.f2()         # SELF就是这个类，调用F2()

    def f2(self):         # 调用属性方法
        b = Auth('joker',18)   # 实例化Auth，得到对象B
        req = Request(b)       # 实例化Request，得到对象REQ
        print(req.user)        #

obj = APIView()     # 得到APIView实例化对象OBJ
obj.dispatch()      # 调用属性方法

4. django中间件

- process_request
- process_view
- process_response
- process_exception
- process_render_template

中间件做过什么？

-权限  -登陆验证

4.1 django的csrf是如何实现？

a. 请求来，第一次来GET，不仅给你数据还给你一个大字符串，但是只能我自己反解，那你提交数据的时候要带着这个字符串
   取消 MIDDLEWARE里面的注释，发送login登录时候，会有CSRFTOKEN的COOKIES
b. 无CSRF时存在隐患
   所有网页都可以向你的网页提交数据
c. Form提交（CSRF）
   {% csrf_token %}
d. Ajax提交（CSRF）
   拿到请求头里面去，发送过去就可以了,CSRF请求头 X-CSRFToken

发生在，process_view方法，因为要检查函数是否被装饰器装饰
- 检查视图是否被 @csrf_exempt （免除csrf认证）
- 去请求体或cookie中获取token

请求时候会随机产生字符串，在访问的时候会携带这个随机字符串

4.2 针对django，fbv模式如何关闭验证

from django.views.decorators.csrf import csrf_exempt（无需验证）,csrf_protect（需验证）

找到需要验证的函数，@csrf_exempt，@csrf_protect

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

from django.views.decorators.csrf import csrf_exempt


@csrf_exempt  # 该函数无需认证
def users(request):
    user_list = ['alex', 'oldboy']
    return HttpResponse(json.dumps((user_list)))

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

from django.views.decorators.csrf import csrf_protect


@csrf_protect  # 该函数需认证
def users(request):
    user_list = ['alex', 'oldboy']
    return HttpResponse(json.dumps((user_list)))

4.3 针对django, cbv模式如何关闭验证

dispatch函数，或者方法，是通过反射来执行相对应的方法，控制它的验证或不验证

from django.views.decorators.csrf import csrf_exempt（无需验证）,csrf_protect（需验证）
from django.utils.decorators import method_decorator

- @method_decorator(csrf_exempt)
- 在dispatch方法中（单独方法无效）

可以针对验证的函数去写，但是不能单独写，要写在@method_decorator里面

@method_decorator（csrf_exempt），@method_decorator（csrf_protect）

from django.views.decorators.csrf import csrf_exempt, csrf_protect
from django.utils.decorators import method_decorator


class StudentsView(View):
    @method_decorator(csrf_exempt)  # 无需验证
    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')

可以针对类，然后指定类里面的方法去验证还是不验证，同样需要写在@method_decorator里面

from django.views.decorators.csrf import csrf_exempt, csrf_protect
from django.utils.decorators import method_decorator


@method_decorator(csrf_exempt, name='dispatch')  # 无需验证
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')

5. 总结 

- cbv
- 本质，基于反射来实现
- 流程：路由，view，dispatch(反射)
- 取消csrf认证（装饰器要加到dispatch方法上且method_decorator装饰）

- csrf
- 基于中间件的process_view方法
- 装饰器给单独函数进行设置（认证或无需认证）

-urlpatterns = [

url(r'^admin/', admin.site.urls),

url(r'^students/', views.StudentsView.as_view()), 点 as_view查看源码

]

class View(object):
    """
    Intentionally simple parent class for all views. Only implements
    dispatch-by-method and simple sanity checking.
    """

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

    def __init__(self, **kwargs):
        """
        Constructor. Called in the URLconf; can contain helpful extra
        keyword arguments, and other things.
        """
        # Go through keyword arguments, and either save their values to our
        # instance, or raise an error.
        for key, value in six.iteritems(kwargs):
            setattr(self, key, value)

    @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))

        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

    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)

django请求周期

FBV          wsgi--中间件--路由--视图--模版--渲染--返回

CBV          wsgi--中间件--路由--dispatch

RESTFRAMEWORK    wsgi--中间件--路由--dispatch