rest_framework

1. 开发模式
        - 普通开发方式（前后端放在一起写）
        - 前后端分离

    2. 后端开发
        为前端提供URL（API/接口的开发）
        注：永远返回HttpResponse

    3. Django FBV、CBV
        FBV,function base view
            def users(request):
                user_list = ['alex','oldboy']
                return HttpResponse(json.dumps((user_list)))

        CBV,class base view
            路由：
                url(r'^students/', views.StudentsView.as_view()),

            视图：
                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')
    4. 列表生成式

        class Foo:
            pass

        class Bar:
            pass

        v = []
        for i in [Foo,Bar]:
            obj = i()
            v.append(obj)


        v = [item() for item in [Foo,Bar]]

        v对象列表

    5. 面向对象
        - 封装
            - 对同一类方法封装到类中
                class File:
                    文件增删改查方法

                Class DB:
                    数据库的方法

            - 将数据封装到对象中
                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)
                obj2 = File(456,999)

            PS: 扩展
                class Request(object):

                    def __init__(self,obj):
                        self.obj = obj

                    @property
                    def user(self):
                        return self.obj.authticate()

                class Auth(object):
                    def __init__(self,name,age):
                        self.name = name
                        self.age = age

                    def authticate(self):
                        return self.name


                class APIView(object):

                    def dispatch(self):
                        self.f2()

                    def f2(self):
                        a = Auth('alex',18)
                        b = Auth('oldboy',18)
                        req = Request(b)
                        print(req.user)

                obj = APIView()
                obj.dispatch()





    1. restful 规范（建议）

    2. django rest framework框架

内容详细：
    0. FBV、CBV
        CBV，基于反射实现根据请求方式不同，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')

        继承（多个类共用的功能，为了避免重复编写）：
            from django.views import View


            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')

        面试题：
            1. django中间件
                - process_request
                - process_view
                - process_response
                - process_exception
                - process_render_template
            2. 使用中间件做过什么？
                - 权限
                - 用户登录验证
                - django的csrf是如何实现？
                    process_view方法
                        - 检查视图是否被 @csrf_exempt （免除csrf认证）
                        - 去请求体或cookie中获取token
            3.
                情况一：
                    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csrf认证
                    def users(request):
                        user_list = ['alex','oldboy']
                        return HttpResponse(json.dumps((user_list)))

                情况二：
                    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_protect # 该函数需csrf认证
                    def users(request):
                        user_list = ['alex','oldboy']
                        return HttpResponse(json.dumps((user_list)))


        CBV小知识,csrf时需要使用
            - @method_decorator(csrf_exempt)
            - 在dispatch方法中（单独方法无效）

            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')

        总结：
            - 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）

            扩展：
                - 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）


    1. restful 规范（建议）
        a. 接口开发

            urlpatterns = [
                # url(r'^admin/', admin.site.urls),
                url(r'^get_order/', views.get_order),
                url(r'^add_order/', views.add_order),
                url(r'^del_order/', views.del_order),
                url(r'^update_order/', views.update_order),
            ]


            def get_order(request):
                return HttpResponse('')


            def add_order(request):
                return HttpResponse('')


            def del_order(request):
                return HttpResponse('')


            def update_order(request):
                return HttpResponse('')

        b. restful 规范（建议）

            1. 根据method不同做不同的操作，示例：

                基于FBV:
                    urlpatterns = [
                        url(r'^order/', views.order),
                    ]

                    def order(request):
                        if request.method == 'GET':
                            return HttpResponse('获取订单')
                        elif request.method == 'POST':
                            return HttpResponse('创建订单')
                        elif request.method == 'PUT':
                            return HttpResponse('更新订单')
                        elif request.method == 'DELETE':
                            return HttpResponse('删除订单')
                基于CBV:
                    urlpatterns = [
                        url(r'^order/', views.OrderView.as_view()),
                    ]

                    class OrderView(View):
                        def get(self,request,*args,**kwargs):
                            return HttpResponse('获取订单')

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

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

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


        c. 谈谈自己对restful api 规范的认识

            10个规则


        注意：推荐使用CBV



    2. django rest framework框架
        pip3 install djangorestframework

        a. 认证
            - 仅使用：
                    from django.views import View
                    from rest_framework.views import APIView
                    from rest_framework.authentication import BasicAuthentication
                    from rest_framework import exceptions
                    from rest_framework.request import Request

                    class MyAuthentication(object):
                        def authenticate(self,request):
                            token = request._request.GET.get('token')
                            # 获取用户名和密码，去数据校验
                            if not token:
                                raise exceptions.AuthenticationFailed('用户认证失败')
                            return ("alex",None)

                        def authenticate_header(self,val):
                            pass

                    class DogView(APIView):
                        authentication_classes = [MyAuthentication,]

                        def get(self,request,*args,**kwargs):
                            print(request)
                            print(request.user)
                            ret  = {
                                'code':1000,
                                'msg':'xxx'
                            }
                            return HttpResponse(json.dumps(ret),status=201)

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

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

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

            - 源码流程：
                dispatch...
***********************************************************************************

内容：
    1. 认证
    2. 权限
    3. 节流（访问频率控制）
    4. 版本

内容：
    1. 认证
        a. 问题1：有些API需要用户登录成功之后，才能访问；有些无需登录就能访问。
        b. 基本使用认证组件
            解决：
                a. 创建两张表
                b. 用户登录（返回token并保存到数据库）
        c. 认证流程原理
            - 见图示

        d. 再看一遍源码
            1. 局部视图使用&全局使用
            2. 匿名是request.user = None

        e. 内置认证类
            1. 认证类，必须继承：from rest_framework.authentication import BaseAuthentication
            2. 其他认证类：BasicAuthentication

        梳理：
            1. 使用
                - 创建类:继承BaseAuthentication； 实现：authenticate方法
                - 返回值：
                    - None,我不管了，下一认证来执行。
                    - raise exceptions.AuthenticationFailed('用户认证失败') # from rest_framework import exceptions
                    - (元素1，元素2)  # 元素1赋值给request.user; 元素2赋值给request.auth

                - 局部使用
                    from rest_framework.authentication import BaseAuthentication,BasicAuthentication
                    class UserInfoView(APIView):
                        """
                        订单相关业务
                        """
                        authentication_classes = [BasicAuthentication,]
                        def get(self,request,*args,**kwargs):
                            print(request.user)
                            return HttpResponse('用户信息')
                - 全局使用：
                    REST_FRAMEWORK = {
                        # 全局使用的认证类
                        "DEFAULT_AUTHENTICATION_CLASSES":['api.utils.auth.FirstAuthtication','api.utils.auth.Authtication', ],
                        # "UNAUTHENTICATED_USER":lambda :"匿名用户"
                        "UNAUTHENTICATED_USER":None, # 匿名，request.user = None
                        "UNAUTHENTICATED_TOKEN":None,# 匿名，request.auth = None
                    }
            2. 源码流程
                - dispatch
                    - 封装request
                        - 获取定义的认证类（全局/局部），通过列表生成时创建对象。
                    - initial
                        - perform_authentication
                            request.user(内部循环....)


    2. 权限
        问题：不用视图不用权限可以访问

        基本使用：

            class MyPermission(object):

                def has_permission(self,request,view):
                    if request.user.user_type != 3:
                        return False
                    return True


                class OrderView(APIView):
                    """
                    订单相关业务(只有SVIP用户有权限)
                    """
                    permission_classes = [MyPermission,]

                    def get(self,request,*args,**kwargs):
                        # request.user
                        # request.auth
                        self.dispatch
                        ret = {'code':1000,'msg':None,'data':None}
                        try:
                            ret['data'] = ORDER_DICT
                        except Exception as e:
                            pass
                        return JsonResponse(ret)

        源码流程：
            - ...

        梳理：
            1. 使用
                - 类，必须继承：BasePermission，必须实现：has_permission方法
                    from rest_framework.permissions import BasePermission

                    class SVIPPermission(BasePermission):
                        message = "必须是SVIP才能访问"
                        def has_permission(self,request,view):
                            if request.user.user_type != 3:
                                return False
                            return True
                - 返回值：
                    - True, 有权访问
                    - False，无权访问
                - 局部
                    class UserInfoView(APIView):
                        """
                        订单相关业务（普通用户、VIP）
                        """
                        permission_classes = [MyPermission1, ]

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

                - 全局
                    REST_FRAMEWORK = {
                        "DEFAULT_PERMISSION_CLASSES":['api.utils.permission.SVIPPermission']
                    }

            2. 源码流程


    3. 访问频率控制（节流）
        问题：控制访问频率
            import time
            VISIT_RECORD = {}

            class VisitThrottle(object):
                """60s内只能访问3次"""

                def __init__(self):
                    self.history = None

                def allow_request(self,request,view):
                    # 1. 获取用户IP
                    remote_addr = request.META.get('REMOTE_ADDR')
                    ctime = time.time()
                    if remote_addr not in VISIT_RECORD:
                        VISIT_RECORD[remote_addr] = [ctime,]
                        return True
                    history = VISIT_RECORD.get(remote_addr)
                    self.history = history

                    while history and history[-1] < ctime - 60:
                        history.pop()

                    if len(history) < 3:
                        history.insert(0,ctime)
                        return True

                    # return True    # 表示可以继续访问
                    # return False # 表示访问频率太高，被限制

                def wait(self):
                    """
                    还需要等多少秒才能访问
                    :return:
                    """
                    ctime = time.time()
                    return 60 - (ctime - self.history[-1])

            class AuthView(APIView):
                """
                用于用户登录认证
                """
                authentication_classes = []
                permission_classes = []
                throttle_classes = [VisitThrottle,]

                def post(self,request,*args,**kwargs):


                    ret = {'code':1000,'msg':None}
                    try:
                        user = request._request.POST.get('username')
                        pwd = request._request.POST.get('password')
                        obj = models.UserInfo.objects.filter(username=user,password=pwd).first()
                        if not obj:
                            ret['code'] = 1001
                            ret['msg'] = "用户名或密码错误"
                        # 为登录用户创建token
                        token = md5(user)
                        # 存在就更新，不存在就创建
                        models.UserToken.objects.update_or_create(user=obj,defaults={'token':token})
                        ret['token'] = token
                    except Exception as e:
                        ret['code'] = 1002
                        ret['msg'] = '请求异常'

                    return JsonResponse(ret)

        内置控制频率类：
            from rest_framework.throttling import BaseThrottle,SimpleRateThrottle
            class VisitThrottle(SimpleRateThrottle):
                scope = "Luffy"

                def get_cache_key(self, request, view):
                    return self.get_ident(request)


            class UserThrottle(SimpleRateThrottle):
                scope = "LuffyUser"

                def get_cache_key(self, request, view):
                    return request.user.username


            REST_FRAMEWORK = {
                # 全局使用的认证类
                "DEFAULT_AUTHENTICATION_CLASSES":['api.utils.auth.FirstAuthtication','api.utils.auth.Authtication', ],
                # "DEFAULT_AUTHENTICATION_CLASSES":['api.utils.auth.FirstAuthtication', ],
                # "UNAUTHENTICATED_USER":lambda :"匿名用户"
                "UNAUTHENTICATED_USER":None, # 匿名，request.user = None
                "UNAUTHENTICATED_TOKEN":None,# 匿名，request.auth = None
                "DEFAULT_PERMISSION_CLASSES":['api.utils.permission.SVIPPermission'],
                "DEFAULT_THROTTLE_CLASSES":["api.utils.throttle.UserThrottle"],
                "DEFAULT_THROTTLE_RATES":{
                    "Luffy":'3/m',
                    "LuffyUser":'10/m',
                }
            }


        梳理：
            a. 基本使用
                - 类， 继承：BaseThrottle，实现：allow_request、wait
                - 类， 继承：SimpleRateThrottle，实现：get_cache_key、scope = "Luffy"（配置文件中的key）

            b. 局部
                class AuthView(APIView):
                    """
                    用于用户登录认证
                    """
                    authentication_classes = []
                    permission_classes = []
                    throttle_classes = [VisitThrottle,] # *******************

                    def post(self,request,*args,**kwargs):

                        ret = {'code':1000,'msg':None}
                        try:
                            user = request._request.POST.get('username')
                            pwd = request._request.POST.get('password')
                            obj = models.UserInfo.objects.filter(username=user,password=pwd).first()
                            if not obj:
                                ret['code'] = 1001
                                ret['msg'] = "用户名或密码错误"
                            # 为登录用户创建token
                            token = md5(user)
                            # 存在就更新，不存在就创建
                            models.UserToken.objects.update_or_create(user=obj,defaults={'token':token})
                            ret['token'] = token
                        except Exception as e:
                            ret['code'] = 1002
                            ret['msg'] = '请求异常'

                        return JsonResponse(ret)

            c. 全局
                REST_FRAMEWORK = {
                    # 全局使用的认证类
                    "DEFAULT_AUTHENTICATION_CLASSES":['api.utils.auth.FirstAuthtication','api.utils.auth.Authtication', ],
                    # "DEFAULT_AUTHENTICATION_CLASSES":['api.utils.auth.FirstAuthtication', ],
                    # "UNAUTHENTICATED_USER":lambda :"匿名用户"
                    "UNAUTHENTICATED_USER":None, # 匿名，request.user = None
                    "UNAUTHENTICATED_TOKEN":None,# 匿名，request.auth = None
                    "DEFAULT_PERMISSION_CLASSES":['api.utils.permission.SVIPPermission'],

                    "DEFAULT_THROTTLE_CLASSES":["api.utils.throttle.UserThrottle"],
                    "DEFAULT_THROTTLE_RATES":{
                        "Luffy":'3/m',
                        "LuffyUser":'10/m',
                    }
                }

    内容：
        1. 中间件

        2. csrf原理

        3. rest 10规范

        4. 面向对象

        5. django请求声明周期

        6. django请求声明周期（包含rest framework框架）
           PS: dispatch

        7. rest framework 认证流程（封装Request.user）

        8. rest framework 权限流程

        9. rest framework 节流流程

    代码：
        认证Demo，
        权限Demo（用户类型不同，权限不同）
        节流Demo（匿名，登录用）

        三组件组合

*********************************************************************************2. Django声明周期
        a. wsgi
            wsgi，是协议。
            wsgiref，是实现了wsgi协议的一个模块。模块本质：一个socket服务端。（Django）
            werkzeug ，是实现了wsgi协议的一个模块。模块本质：一个socket服务端（Flask框架）
            tornado ，是实现了wsgi协议的一个模块。模块本质：一个socket服务端（Flask框架）
            uwsgi，是实现了wsgi协议的一个模块。模块本质：一个socket服务端。


    3. Django生命周期（rest framework）


    4. 中间件&装饰器
        - 适用于所有请求批量做操作
            场景：
                - 基于角色的权限控制
                - 用户认证
                - csrf,（说原理）
                - session（说原理）
                - 黑名单
                - 日志记录
    5. rest 框架原理
        a. 认证流程
        b. 权限
        c. 节流


内容概要：
    1. 版本      *
    2. 解析器 *
    3. 序列化 ****
        - 请求数据进行校验
        - QuerySet进行序列化
    4. 分页   **
    5. 路由   **
    6. 视图   **
    7. 渲染器 *


内容详细：
    1. 版本
        a. URL中通过GET传参()
            自定义：
                http://127.0.0.1:8000/api/users/?version=v2

                class ParamVersion(object):
                    def determine_version(self, request, *args, **kwargs):
                        version = request.query_params.get('version')
                        return version

                class UsersView(APIView):

                    versioning_class = ParamVersion
                    def get(self,request,*args,**kwargs):
                        #version = request._request.GET.get('version')
                        #print(version)
                        # version = request.query_params.get('version')
                        # print(version)

                        print(request.version)

                        return HttpResponse('用户列表')


        b. 在URL中传参（推荐使用）

            urlpatterns = [
                # url(r'^admin/', admin.site.urls),
                url(r'^(?P<version>[v1|v2]+)/users/$', views.UsersView.as_view()),
            ]


            REST_FRAMEWORK = {
                "DEFAULT_VERSIONING_CLASS":"rest_framework.versioning.URLPathVersioning",
                "DEFAULT_VERSION":'v1',
                "ALLOWED_VERSIONS":['v1','v2'],
                "VERSION_PARAM":'version',
            }

            class UsersView(APIView):

                def get(self,request,*args,**kwargs):
                    print(request.version)
                    return HttpResponse('用户列表')

        总结：
            使用：
                配置文件：
                    REST_FRAMEWORK = {
                        "DEFAULT_VERSIONING_CLASS":"rest_framework.versioning.URLPathVersioning",
                        "DEFAULT_VERSION":'v1',
                        "ALLOWED_VERSIONS":['v1','v2'],
                        "VERSION_PARAM":'version',
                    }
                路由系统：

                    urlpatterns = [
                        # url(r'^admin/', admin.site.urls),
                        url(r'^api/', include('api.urls')),
                    ]

                    urlpatterns = [
                        # url(r'^admin/', admin.site.urls),
                        url(r'^(?P<version>[v1|v2]+)/users/$', views.UsersView.as_view(),name='uuu'),
                    ]


                视图：

                    class UsersView(APIView):

                    def get(self,request,*args,**kwargs):

                        # 1. 获取版本
                        print(request.version)

                        # 2. 获取处理版本的对象
                        print(request.versioning_scheme)

                        # 3. 反向生成URL（rest framework）
                        u1 = request.versioning_scheme.reverse(viewname='uuu',request=request)
                        print(u1)

                        # 4. 反向生成URL
                        u2 = reverse(viewname='uuu',kwargs={'version':2})
                        print(u2)

                        return HttpResponse('用户列表')

    2. 解析器
        前戏：django:request.POST/ request.body
            1. 请求头要求：
                Content-Type: application/x-www-form-urlencoded
                PS: 如果请求头中的 Content-Type: application/x-www-form-urlencoded，request.POST中才有值（去request.body中解析数据）。
            2. 数据格式要求：
                  name=alex&age=18&gender=男

            如：
                a. form表单提交
                    <form method...>
                        input...

                    </form>

                b. ajax提交
                    $.ajax({
                        url:...
                        type:POST,
                        data:{name:alex,age=18} # 内部转化 name=alex&age=18&gender=男
                    })

                    情况一：
                        $.ajax({
                            url:...
                            type:POST,
                            headers:{'Content-Type':"application/json"}
                            data:{name:alex,age=18} # 内部转化 name=alex&age=18&gender=男
                        })
                        # body有值；POST无
                    情况二：
                        $.ajax({
                            url:...
                            type:POST,
                            headers:{'Content-Type':"application/json"}
                            data:JSON.stringfy({name:alex,age=18}) # {name:alex,age:18...}
                        })
                        # body有值；POST无
                        # json.loads(request.body)

        rest_framework 解析器，对请求体数据进行解析

        总结：
            使用：
                配置：
                    REST_FRAMEWORK = {
                        "DEFAULT_VERSIONING_CLASS":"rest_framework.versioning.URLPathVersioning",
                        "DEFAULT_VERSION":'v1',
                        "ALLOWED_VERSIONS":['v1','v2'],
                        "VERSION_PARAM":'version',

                        "DEFAULT_PARSER_CLASSES":['rest_framework.parsers.JSONParser','rest_framework.parsers.FormParser']
                    }

                使用：
                    class ParserView(APIView):
                        # parser_classes = [JSONParser,FormParser,]
                        """
                        JSONParser:表示只能解析content-type:application/json头
                        JSONParser:表示只能解析content-type:application/x-www-form-urlencoded头
                        """

                        def post(self,request,*args,**kwargs):
                            """
                            允许用户发送JSON格式数据
                                a. content-type: application/json
                                b. {'name':'alex',age:18}
                            :param request:
                            :param args:
                            :param kwargs:
                            :return:
                            """
                            """
                            1. 获取用户请求
                            2. 获取用户请求体
                            3. 根据用户请求头 和 parser_classes = [JSONParser,FormParser,] 中支持的请求头进行比较
                            4. JSONParser对象去请求体
                            5. request.data
                            """
                            print(request.data)


                            return HttpResponse('ParserView')


            源码流程 & 本质：
                a. 本质
                    请求头 :...
                    状态码: ...
                    请求方法:...
                b. 源码流程
                    - dispatch: request封装
                    - request.data



    3. 序列化

        序列化：
            部分总结：
                1. 写类
                    class RolesSerializer(serializers.Serializer):
                        id = serializers.IntegerField()
                        title = serializers.CharField()

                    class UserInfoSerializer(serializers.ModelSerializer):
                        class Meta:
                            model = models.UserInfo
                            # fields = "__all__"
                            fields = ['id','username','password',]

                2. 字段
                    a. title = serializers.CharField(source="xxx.xxx.xx.xx")
                    b. title = serializers.SerializerMethodField()
                       class UserInfoSerializer(serializers.ModelSerializer):
                            rls = serializers.SerializerMethodField()  # 自定义显示

                            class Meta:
                                model = models.UserInfo
                                fields = ['id','username','password','rls',]

                            # 自定义方法
                            def get_rls(self, row):
                                role_obj_list = row.roles.all()

                                ret = []
                                for item in role_obj_list:
                                    ret.append({'id':item.id,'title':item.title})
                                return ret
                    c. 自定义类

                3. 自动序列化连表
                    class UserInfoSerializer(serializers.ModelSerializer):
                    class Meta:
                        model = models.UserInfo
                        # fields = "__all__"
                        fields = ['id','username','password','group','roles']
                        depth = 1 # 0 ~ 10

                4. 生成链接
                    class UserInfoSerializer(serializers.ModelSerializer):
                        group = serializers.HyperlinkedIdentityField(view_name='gp',lookup_field='group_id',lookup_url_kwarg='xxx')
                        class Meta:
                            model = models.UserInfo
                            # fields = "__all__"
                            fields = ['id','username','password','group','roles']
                            depth = 0 # 0 ~ 10

                    class UserInfoView(APIView):
                        def get(self,request,*args,**kwargs):

                            users = models.UserInfo.objects.all()

                            ser = UserInfoSerializer(instance=users,many=True,context={'request': request})
                            ret = json.dumps(ser.data, ensure_ascii=False)
                            return HttpResponse(ret)

            源码：
                对象， Serializer类处理；
                QuerySet，ListSerializer类处理；
                # ser.data

        请求数据校验：

                class XXValidator(object):
                    def __init__(self, base):
                        self.base = base

                    def __call__(self, value):
                        if not value.startswith(self.base):
                            message = '标题必须以 %s 为开头。' % self.base
                            raise serializers.ValidationError(message)

                    def set_context(self, serializer_field):
                        """
                        This hook is called by the serializer instance,
                        prior to the validation call being made.
                        """
                        # 执行验证之前调用,serializer_fields是当前字段对象
                        pass

                class UserGroupSerializer(serializers.Serializer):
                    title = serializers.CharField(error_messages={'required':'标题不能为空'},validators=[XXValidator('老男人'),])


                class UserGroupView(APIView):

                    def post(self,request,*args,**kwargs):

                        ser = UserGroupSerializer(data=request.data)
                        if ser.is_valid():
                            print(ser.validated_data['title'])
                        else:
                            print(ser.errors)

                        return HttpResponse('提交数据')


            问： 自定义验证规则时，需要钩子函数？请问钩子函数如何写？
********************************************************************************
内容：
    0. 序列化源码

    1. 分页
        a. 分页，看第n页，每页显示n条数据；
            from rest_framework.pagination import PageNumberPagination

            class MyPageNumberPagination(PageNumberPagination):

                page_size = 2
                page_size_query_param = 'size'
                max_page_size = 5
                page_query_param = 'page'

            class Pager1View(APIView):

                def get(self,request,*args,**kwargs):

                    # 获取所有数据
                    roles = models.Role.objects.all()

                    # 创建分页对象
                    # pg = MyPageNumberPagination()
                    pg = PageNumberPagination()

                    # 在数据库中获取分页的数据
                    pager_roles = pg.paginate_queryset(queryset=roles,request=request,view=self)

                    # 对数据进行序列化
                    ser = PagerSerialiser(instance=pager_roles, many=True)

                    return Response(ser.data)
                    # return pg.get_paginated_response(ser.data)


        b. 分页，在n个位置，向后查看n条数据；

                from api.utils.serializsers.pager import PagerSerialiser
                from rest_framework.response import Response
                from rest_framework.pagination import PageNumberPagination,LimitOffsetPagination


                class MyLimitOffsetPagination(LimitOffsetPagination):
                    default_limit = 2
                    limit_query_param = 'limit'
                    offset_query_param = 'offset'
                    max_limit = 5


                class Pager1View(APIView):

                    def get(self,request,*args,**kwargs):

                        # 获取所有数据
                        roles = models.Role.objects.all()

                        # 创建分页对象
                        # pg = MyLimitOffsetPagination()
                        pg = LimitOffsetPagination()

                        # 在数据库中获取分页的数据
                        pager_roles = pg.paginate_queryset(queryset=roles,request=request,view=self)

                        # 对数据进行序列化
                        ser = PagerSerialiser(instance=pager_roles, many=True)

                        return Response(ser.data)
                        # return pg.get_paginated_response(ser.data)



        c. 加密分页，上一页和下一页。

            from api.utils.serializsers.pager import PagerSerialiser
            from rest_framework.response import Response
            from rest_framework.pagination import PageNumberPagination,LimitOffsetPagination,CursorPagination

            class MyCursorPagination(CursorPagination):
                cursor_query_param = 'cursor'
                page_size = 2
                ordering = 'id'
                page_size_query_param = None
                max_page_size = None

            class Pager1View(APIView):

                def get(self,request,*args,**kwargs):

                    # 获取所有数据
                    roles = models.Role.objects.all()

                    # 创建分页对象
                    # pg = CursorPagination()
                    pg = MyCursorPagination()

                    # 在数据库中获取分页的数据
                    pager_roles = pg.paginate_queryset(queryset=roles,request=request,view=self)

                    # 对数据进行序列化
                    ser = PagerSerialiser(instance=pager_roles, many=True)

                    # return Response(ser.data)
                    return pg.get_paginated_response(ser.data)
        总结：
            1. 数据量大的话，如何做分页？
                - 数据库性能相关？
    2. 视图
        a. 过去
            class Pager1View(View):
                pass

        b. 现在
            class Pager1View(APIView): # View
                pass

        c. 无用

            from api.utils.serializsers.pager import PagerSerialiser
            from rest_framework.generics import GenericAPIView

            class View1View(GenericAPIView): # APIView
                queryset = models.Role.objects.all()
                serializer_class = PagerSerialiser
                pagination_class = PageNumberPagination
                def get(self,request,*args,**kwargs):
                    # 获取数据
                    roles = self.get_queryset() # models.Role.objects.all()

                    # [1, 1000,]     [1,10]
                    pager_roles = self.paginate_queryset(roles)

                    # 序列化
                    ser = self.get_serializer(instance=pager_roles,many=True)

                    return Response(ser.data)

        d. GenericViewSet(ViewSetMixin, generics.GenericAPIView):

            路由：
                url(r'^(?P<version>[v1|v2]+)/v1/$', views.View1View.as_view({'get': 'list'})),

            视图：
                from api.utils.serializsers.pager import PagerSerialiser
                from rest_framework.viewsets import GenericViewSet

                class View1View(GenericViewSet):
                    queryset = models.Role.objects.all()
                    serializer_class = PagerSerialiser
                    pagination_class = PageNumberPagination

                    def list(self, request, *args, **kwargs):
                        # 获取数据
                        roles = self.get_queryset()  # models.Role.objects.all()

                        # [1, 1000,]     [1,10]
                        pager_roles = self.paginate_queryset(roles)

                        # 序列化
                        ser = self.get_serializer(instance=pager_roles, many=True)

                        return Response(ser.data)

        e.
            路由系统：
                url(r'^(?P<version>[v1|v2]+)/v1/$', views.View1View.as_view({'get': 'list','post':'create'})),
                url(r'^(?P<version>[v1|v2]+)/v1/(?P<pk>\d+)/$', views.View1View.as_view({'get': 'retrieve','delete':'destroy','put':'update','patch':'partial_update'})),

            视图：
                from api.utils.serializsers.pager import PagerSerialiser
                from rest_framework.viewsets import GenericViewSet,ModelViewSet
                from rest_framework.mixins import ListModelMixin,CreateModelMixin

                class View1View(ModelViewSet):
                    queryset = models.Role.objects.all()
                    serializer_class = PagerSerialiser
                    pagination_class = PageNumberPagination

                PS: class View1View(CreateModelMixin,GenericViewSet):
        总结：
            a. 增删改查 ModelViewSet
            b. 增删     CreateModelMixin,DestroyModelMixin  GenericViewSet
            c. 复杂逻辑  GenericViewSet 或 APIView

            PS: 还债：
                GenericAPIView.get_object
                    check_object_permissions
                        has_object_permission

    3. 路由
        a.
            url(r'^(?P<version>[v1|v2]+)/parser/$', views.ParserView.as_view()),

        b.
            url(r'^(?P<version>[v1|v2]+)/v1/$', views.View1View.as_view({'get': 'list','post':'create'})),

        c.
            # http://127.0.0.1:8000/api/v1/v1/?format=json
            url(r'^(?P<version>[v1|v2]+)/v1/$', views.View1View.as_view({'get': 'list','post':'create'})),
            # http://127.0.0.1:8000/api/v1/v1.json
            url(r'^(?P<version>[v1|v2]+)/v1\.(?P<format>\w+)$', views.View1View.as_view({'get': 'list','post':'create'})),

            url(r'^(?P<version>[v1|v2]+)/v1/(?P<pk>\d+)/$', views.View1View.as_view({'get': 'retrieve','delete':'destroy','put':'update','patch':'partial_update'})),
            url(r'^(?P<version>[v1|v2]+)/v1/(?P<pk>\d+)\.(?P<format>\w+)$', views.View1View.as_view({'get': 'retrieve','delete':'destroy','put':'update','patch':'partial_update'})),
        d.
            from api import views
            from rest_framework import routers


            router = routers.DefaultRouter()
            router.register(r'xxxxx', views.View1View)
            router.register(r'rt', views.View1View)

            urlpatterns = [
                url(r'^(?P<version>[v1|v2]+)/', include(router.urls)),
            ]

    4. 渲染
        from rest_framework.renderers import JSONRenderer,BrowsableAPIRenderer

        class TestView(APIView):
            # renderer_classes = [JSONRenderer,BrowsableAPIRenderer]
            def get(self, request, *args, **kwargs):
                # 获取所有数据
                roles = models.Role.objects.all()

                # 创建分页对象
                # pg = CursorPagination()
                pg = MyCursorPagination()

                # 在数据库中获取分页的数据
                pager_roles = pg.paginate_queryset(queryset=roles, request=request, view=self)

                # 对数据进行序列化
                ser = PagerSerialiser(instance=pager_roles, many=True)

                return Response(ser.data)


        REST_FRAMEWORK = {
            "DEFAULT_VERSIONING_CLASS":"rest_framework.versioning.URLPathVersioning",
            "DEFAULT_VERSION":'v1',
            "ALLOWED_VERSIONS":['v1','v2'],
            "VERSION_PARAM":'version',
            "DEFAULT_PARSER_CLASSES":['rest_framework.parsers.JSONParser','rest_framework.parsers.FormParser'],
            "PAGE_SIZE":2,

            "DEFAULT_RENDERER_CLASSES":[
                'rest_framework.renderers.JSONRenderer',
                'rest_framework.renderers.BrowsableAPIRenderer',
            ]
        }

    5. django组件：contenttype**********************************************************************************
内容：
    0. 序列化源码

    1. 分页
        a. 分页，看第n页，每页显示n条数据；
            from rest_framework.pagination import PageNumberPagination

            class MyPageNumberPagination(PageNumberPagination):

                page_size = 2
                page_size_query_param = 'size'
                max_page_size = 5
                page_query_param = 'page'

            class Pager1View(APIView):

                def get(self,request,*args,**kwargs):

                    # 获取所有数据
                    roles = models.Role.objects.all()

                    # 创建分页对象
                    # pg = MyPageNumberPagination()
                    pg = PageNumberPagination()

                    # 在数据库中获取分页的数据
                    pager_roles = pg.paginate_queryset(queryset=roles,request=request,view=self)

                    # 对数据进行序列化
                    ser = PagerSerialiser(instance=pager_roles, many=True)

                    return Response(ser.data)
                    # return pg.get_paginated_response(ser.data)


        b. 分页，在n个位置，向后查看n条数据；

                from api.utils.serializsers.pager import PagerSerialiser
                from rest_framework.response import Response
                from rest_framework.pagination import PageNumberPagination,LimitOffsetPagination


                class MyLimitOffsetPagination(LimitOffsetPagination):
                    default_limit = 2
                    limit_query_param = 'limit'
                    offset_query_param = 'offset'
                    max_limit = 5


                class Pager1View(APIView):

                    def get(self,request,*args,**kwargs):

                        # 获取所有数据
                        roles = models.Role.objects.all()

                        # 创建分页对象
                        # pg = MyLimitOffsetPagination()
                        pg = LimitOffsetPagination()

                        # 在数据库中获取分页的数据
                        pager_roles = pg.paginate_queryset(queryset=roles,request=request,view=self)

                        # 对数据进行序列化
                        ser = PagerSerialiser(instance=pager_roles, many=True)

                        return Response(ser.data)
                        # return pg.get_paginated_response(ser.data)



        c. 加密分页，上一页和下一页。

            from api.utils.serializsers.pager import PagerSerialiser
            from rest_framework.response import Response
            from rest_framework.pagination import PageNumberPagination,LimitOffsetPagination,CursorPagination

            class MyCursorPagination(CursorPagination):
                cursor_query_param = 'cursor'
                page_size = 2
                ordering = 'id'
                page_size_query_param = None
                max_page_size = None

            class Pager1View(APIView):

                def get(self,request,*args,**kwargs):

                    # 获取所有数据
                    roles = models.Role.objects.all()

                    # 创建分页对象
                    # pg = CursorPagination()
                    pg = MyCursorPagination()

                    # 在数据库中获取分页的数据
                    pager_roles = pg.paginate_queryset(queryset=roles,request=request,view=self)

                    # 对数据进行序列化
                    ser = PagerSerialiser(instance=pager_roles, many=True)

                    # return Response(ser.data)
                    return pg.get_paginated_response(ser.data)
        总结：
            1. 数据量大的话，如何做分页？
                - 数据库性能相关？
    2. 视图
        a. 过去
            class Pager1View(View):
                pass

        b. 现在
            class Pager1View(APIView): # View
                pass

        c. 无用

            from api.utils.serializsers.pager import PagerSerialiser
            from rest_framework.generics import GenericAPIView

            class View1View(GenericAPIView): # APIView
                queryset = models.Role.objects.all()
                serializer_class = PagerSerialiser
                pagination_class = PageNumberPagination
                def get(self,request,*args,**kwargs):
                    # 获取数据
                    roles = self.get_queryset() # models.Role.objects.all()

                    # [1, 1000,]     [1,10]
                    pager_roles = self.paginate_queryset(roles)

                    # 序列化
                    ser = self.get_serializer(instance=pager_roles,many=True)

                    return Response(ser.data)

        d. GenericViewSet(ViewSetMixin, generics.GenericAPIView):

            路由：
                url(r'^(?P<version>[v1|v2]+)/v1/$', views.View1View.as_view({'get': 'list'})),

            视图：
                from api.utils.serializsers.pager import PagerSerialiser
                from rest_framework.viewsets import GenericViewSet

                class View1View(GenericViewSet):
                    queryset = models.Role.objects.all()
                    serializer_class = PagerSerialiser
                    pagination_class = PageNumberPagination

                    def list(self, request, *args, **kwargs):
                        # 获取数据
                        roles = self.get_queryset()  # models.Role.objects.all()

                        # [1, 1000,]     [1,10]
                        pager_roles = self.paginate_queryset(roles)

                        # 序列化
                        ser = self.get_serializer(instance=pager_roles, many=True)

                        return Response(ser.data)

        e.
            路由系统：
                url(r'^(?P<version>[v1|v2]+)/v1/$', views.View1View.as_view({'get': 'list','post':'create'})),
                url(r'^(?P<version>[v1|v2]+)/v1/(?P<pk>\d+)/$', views.View1View.as_view({'get': 'retrieve','delete':'destroy','put':'update','patch':'partial_update'})),

            视图：
                from api.utils.serializsers.pager import PagerSerialiser
                from rest_framework.viewsets import GenericViewSet,ModelViewSet
                from rest_framework.mixins import ListModelMixin,CreateModelMixin

                class View1View(ModelViewSet):
                    queryset = models.Role.objects.all()
                    serializer_class = PagerSerialiser
                    pagination_class = PageNumberPagination

                PS: class View1View(CreateModelMixin,GenericViewSet):
        总结：
            a. 增删改查 ModelViewSet
            b. 增删     CreateModelMixin,DestroyModelMixin  GenericViewSet
            c. 复杂逻辑  GenericViewSet 或 APIView

            PS: 还债：
                GenericAPIView.get_object
                    check_object_permissions
                        has_object_permission

    3. 路由
        a.
            url(r'^(?P<version>[v1|v2]+)/parser/$', views.ParserView.as_view()),

        b.
            url(r'^(?P<version>[v1|v2]+)/v1/$', views.View1View.as_view({'get': 'list','post':'create'})),

        c.
            # http://127.0.0.1:8000/api/v1/v1/?format=json
            url(r'^(?P<version>[v1|v2]+)/v1/$', views.View1View.as_view({'get': 'list','post':'create'})),
            # http://127.0.0.1:8000/api/v1/v1.json
            url(r'^(?P<version>[v1|v2]+)/v1\.(?P<format>\w+)$', views.View1View.as_view({'get': 'list','post':'create'})),

            url(r'^(?P<version>[v1|v2]+)/v1/(?P<pk>\d+)/$', views.View1View.as_view({'get': 'retrieve','delete':'destroy','put':'update','patch':'partial_update'})),
            url(r'^(?P<version>[v1|v2]+)/v1/(?P<pk>\d+)\.(?P<format>\w+)$', views.View1View.as_view({'get': 'retrieve','delete':'destroy','put':'update','patch':'partial_update'})),
        d.
            from api import views
            from rest_framework import routers


            router = routers.DefaultRouter()
            router.register(r'xxxxx', views.View1View)
            router.register(r'rt', views.View1View)

            urlpatterns = [
                url(r'^(?P<version>[v1|v2]+)/', include(router.urls)),
            ]

    4. 渲染
        from rest_framework.renderers import JSONRenderer,BrowsableAPIRenderer

        class TestView(APIView):
            # renderer_classes = [JSONRenderer,BrowsableAPIRenderer]
            def get(self, request, *args, **kwargs):
                # 获取所有数据
                roles = models.Role.objects.all()

                # 创建分页对象
                # pg = CursorPagination()
                pg = MyCursorPagination()

                # 在数据库中获取分页的数据
                pager_roles = pg.paginate_queryset(queryset=roles, request=request, view=self)

                # 对数据进行序列化
                ser = PagerSerialiser(instance=pager_roles, many=True)

                return Response(ser.data)


        REST_FRAMEWORK = {
            "DEFAULT_VERSIONING_CLASS":"rest_framework.versioning.URLPathVersioning",
            "DEFAULT_VERSION":'v1',
            "ALLOWED_VERSIONS":['v1','v2'],
            "VERSION_PARAM":'version',
            "DEFAULT_PARSER_CLASSES":['rest_framework.parsers.JSONParser','rest_framework.parsers.FormParser'],
            "PAGE_SIZE":2,

            "DEFAULT_RENDERER_CLASSES":[
                'rest_framework.renderers.JSONRenderer',
                'rest_framework.renderers.BrowsableAPIRenderer',
            ]
        }

    5. django组件：contenttype