python 全栈开发，Day100(restful 接口,DRF组件,DRF跨域(cors组件))

昨日内容回顾

1. 为什么要做前后端分离？
    - 前后端交给不同的人来编写，职责划分明确。方便快速开发
    - 针对pc,手机,ipad,微信,支付宝... 使用同一个接口
    
2. 简述http协议？
    - 基于socket
    - 数据格式：
        "GET /index?name=123&age=19 http1.1
host:www.luffyciti.com
content-type:application/json...

"
        
        "POST /index http1.1
host:www.luffyciti.com
content-type:application/json...

{name:'alex',age:18}"
        
        "POST /index http1.1
host:www.luffyciti.com
content-type:application/enform.....

name=alex&age=18&xx=19"
    - 无状态短链接
        一次请求一次响应之后断开连接
        
3. 简述restful 规范？
    https://www.luffycity.com/api/v1/courses/?sub_category=0
    看上面一段url，可以说出5个
    1. 使用https代替http  2.在URL中体现自己写的是API 3. 在URL中体现版本  4. 使用名词 5.参数要合理
    之后，请求方式，响应信息。可以说后面5个
    6. 根据请求方式不同,处理不同的操作 7.
    
    
4. django rest framework组件的作用？
    - 快速实现restful 规范
        
5. 列举django rest framework组件（10）？
    
6. 路飞的表结构

View Code

一、restful 接口

根据昨天代码，继续编写。

或者下载代码：

https://github.com/987334176/luffycity/archive/v1.2.zip

注意：删除api目录下的views.py文件，它没有用了

下载数据库使用：

https://github.com/987334176/luffycity/blob/master/db.sqlite3

第一种方式

修改api_urls.py

from django.conf.urls import url
from api.views import course,degreecourse

urlpatterns = [
    # url(r'login/$', views.LoginView.as_view()),
    url(r'courses/$',course.CoursesView.as_view()),
    url(r'courses/(?P<pk>d+)/$',course.CourseDetailView.as_view()),

    url(r'degreecourse/$',degreecourse.DegreeCourseView.as_view()),
    url(r'degreecourse/teachers/$',degreecourse.DegreeCourseTeachersView.as_view()),
    url(r'degreecourse/scholarship/$',degreecourse.DegreeCourseScholarshipView.as_view()),

]

View Code

修改views目录下的course.py

from rest_framework.views import APIView
from rest_framework.response import Response

from api import models
from api.serializers.course import CourseModelSerializer

from api.utils.response import BaseResponse
from api.utils.serialization_general import SerializedData


class CoursesView(APIView):

    def get(self, request, *args, **kwargs):
        """
        查询所有
        :param request:
        :param args:
        :param kwargs:
        :return:
        """
        queryset = models.Course.objects.all()
        serializer_class = CourseModelSerializer
        data = SerializedData(request, queryset, serializer_class).get_data()
        return Response(data)

    def post(self, request, *args, **kwargs):
        """
        增加一条
        :param request:
        :param args:
        :param kwargs:
        :return:
        """

class CourseDetailView(APIView):
    def get(self, request, pk,*args, **kwargs):
        """
        查询单个
        :param request:
        :param pk:
        :param args:
        :param kwargs:
        :return:
        """
    def put(self, request, pk,*args, **kwargs):
        """
        修改单个
        :param request:
        :param pk:
        :param args:
        :param kwargs:
        :return:
        """
    def delete(self, request, pk,*args, **kwargs):
        """
        删除单个
        :param request:
        :param pk:
        :param args:
        :param kwargs:
        :return:
        """

View Code

上面的方式，更趋近于原始

第二种方式(推荐)

django-rst-framework为我们提供了ViewSet类, ViewSet为我们提供了默认的URL结构, 使得我们能更专注于API本身. ViewSet类与View类几乎是相同的, 但提供的是read或update, 而不是http动作get或put.

ViewSet类在实例化后, 通过Router类, 最终将URL与ViewSet方法绑定

ViewSet类的父类ViewSetMixin，其实重写了as_view方法

@classonlymethod
    def as_view(cls, actions=None, **initkwargs):
        """
        Because of the way class based views create a closure around the
        instantiated view, we need to totally reimplement `.as_view`,
        and slightly modify the view function that is created and returned.
        """
        ...

那么url方式也发生了变化

修改api_urls.py

from django.conf.urls import url
from api.views import course

urlpatterns = [
    url(r'courses/$', course.CoursesView.as_view({'get': 'list', 'post': 'create'})),
    url(r'courses/(?P<pk>d+)/$', course.CoursesView.as_view({'get': 'retrieve', 'put': 'update', 'delete': 'destroy'}))
]

View Code

解释：看这一段{'get':'list','post':'create'}

它表示get请求时，转发到list方法。post请求转发到create方法。

这里面定义的方法名，都是约定俗成的。推荐使用这些名字！也可以自定义。

修改views目录下的course.py

from rest_framework.views import APIView
from rest_framework.viewsets import ViewSetMixin
from rest_framework.response import Response

from api import models
from api.serializers.course import CourseModelSerializer

from api.utils.response import BaseResponse
from api.utils.serialization_general import SerializedData


class CoursesView(ViewSetMixin,APIView):

    def list(self, request, *args, **kwargs):
        """
        查询所有
        :param request:
        :param args:
        :param kwargs:
        :return:
        """
        queryset = models.Course.objects.all()
        serializer_class = CourseModelSerializer
        data = SerializedData(request, queryset, serializer_class).get_data()
        return Response(data)

    def create(self, request, *args, **kwargs):
        """
        增加一条
        :param request:
        :param args:
        :param kwargs:
        :return:
        """

class CourseDetailView(APIView):
    def retrieve(self, request, pk,*args, **kwargs):
        """
        查询单个
        :param request:
        :param pk:
        :param args:
        :param kwargs:
        :return:
        """
    def update(self, request, pk,*args, **kwargs):
        """
        修改单个
        :param request:
        :param pk:
        :param args:
        :param kwargs:
        :return:
        """
    def destroy(self, request, pk,*args, **kwargs):
        """
        删除单个
        :param request:
        :param pk:
        :param args:
        :param kwargs:
        :return:
        """

View Code

以上方式适用于：用户请求处理时业务逻辑复杂的情况。

注意：如果继承了GenericViewSet，并且返回序列化数据使用了Response

必须要定义queryset属性，否则报错

看源码

必须要定义queryset变量，否则执行assert(断言)。

还有一种解决方式，使用JSONRenderer。它也可以返回json数据，但是没有像Response那样，有好看的页面！

三、DRF跨域(cors组件)

运行的vue项目，发现出现跨域

查看Pycharm控制台输出：

[18/Aug/2018 20:14:31] "GET /api/v1/courses/ HTTP/1.1" 200 212

可以发现，请求实际已经到达了后端。并且做了正确的返回，但是浏览器拒绝接收！

这为什么呢？这是因为浏览器的同源策略

1.什么是同源策略

同源：页面地址拥有相同的协议，域名，以及端口号。

同源策略: 页面A中的脚本不能访问不同源的页面B的cookie、localStorage以及IndexDB,也不能获取页面B的DOM信息，另外在使用AJAX时也会受到相关限制。

2.同源策略的目的

主要是出于安全方面的考虑。现在的网页都用cookie来进行身份验证，如果不限制读取，网页B里的恶意脚本代码可以随意模仿真实用户进行操作。

关于更多的同源策略信息，请参考链接：

http://www.ruanyifeng.com/blog/2016/04/same-origin-policy.html

总结：

浏览器具有同源策略，打开某个网站后，通过ajax向另外一个网站发送http请求时候，数据回来时会被浏览器阻止（跨域）

解决跨域

方式一

在api端设置响应头 CORS

修改views目录下的course.py，增加响应头

from rest_framework.views import APIView
from rest_framework.viewsets import ViewSetMixin
from rest_framework.response import Response

from api import models
from api.serializers.course import CourseModelSerializer

from api.utils.response import BaseResponse
from api.utils.serialization_general import SerializedData


class CoursesView(ViewSetMixin,APIView):

    def list(self, request, *args, **kwargs):
        """
        查询所有
        :param request:
        :param args:
        :param kwargs:
        :return:
        """
        queryset = models.Course.objects.all()
        serializer_class = CourseModelSerializer
        data = SerializedData(request, queryset, serializer_class).get_data()
        # 增加响应头,http://localhost:8080表示前端的地址
        return Response(data,headers={'Access-Control-Allow-Origin': 'http://localhost:8080'})

    def create(self, request, *args, **kwargs):
        """
        增加一条
        :param request:
        :param args:
        :param kwargs:
        :return:
        """

class CourseDetailView(APIView):
    def retrieve(self, request, pk,*args, **kwargs):
        """
        查询单个
        :param request:
        :param pk:
        :param args:
        :param kwargs:
        :return:
        """
    def update(self, request, pk,*args, **kwargs):
        """
        修改单个
        :param request:
        :param pk:
        :param args:
        :param kwargs:
        :return:
        """
    def destroy(self, request, pk,*args, **kwargs):
        """
        删除单个
        :param request:
        :param pk:
        :param args:
        :param kwargs:
        :return:
        """

View Code

Access-Control-Allow-Origin字段，表示http://localhost:8080可以请求数据。该字段也可以设为星号，表示同意任意跨源请求

客户端浏览器检查自己的域是否在允许列表中，决定是否处理响应

刷新vue页面，发现没有报错了。说明接收了数据！

上面是简单请求

简单请求 OR 非简单请求

条件：

1、请求方式：HEAD、GET、POST
2、请求头信息：
    Accept
    Accept-Language
    Content-Language
    Last-Event-ID
    Content-Type 对应的值是以下三个中的任意一个
        application/x-www-form-urlencoded
        multipart/form-data
        text/plain

注意：同时满足以上两个条件时，则是简单请求，否则为复杂请求

简单请求和非简单请求的区别

简单请求：一次请求
非简单请求：两次请求，在发送数据之前会先发一次请求用于做“预检”，只有“预检”通过后才再发送一次请求用

关于"预检"

- 请求方式：OPTIONS
- "预检"其实做检查，检查如果通过则允许传输数据，检查不通过则不再发送真正想要发送的消息
- 如何"预检"
     => 如果复杂请求是PUT等请求，则服务端需要设置允许某请求，否则"预检"不通过
        Access-Control-Request-Method
     => 如果复杂请求设置了请求头，则服务端需要设置允许某请求头，否则"预检"不通过
        Access-Control-Request-Headers        text/plain

数据展示

修改settings.py，将分页改成20

REST_FRAMEWORK = {
    'DEFAULT_VERSIONING_CLASS':'rest_framework.versioning.URLPathVersioning',
    'VERSION_PARAM':'version',
    'DEFAULT_VERSION':'v1',
    'ALLOWED_VERSIONS':['v1','v2'],
    'PAGE_SIZE':20,
    'DEFAULT_PAGINATION_CLASS': 'rest_framework.pagination.PageNumberPagination',
}

View Code

修改vue项目的HelloWorld.vue

<template>
  <div class="hello">
    <h1>{{ msg }}</h1>
    <h1>课程列表</h1>
    <ul v-for="item in courseList">
      <li>{{item.name}}</li>
    </ul>
  </div>
</template>

<script>
export default {
  name: 'HelloWorld',
  data () {
    return {
      msg: '欢迎使用路飞学城',
      courseList:[],
    }
  },
  mounted(){  //页面加载完成后
    this.initCourse();  //执行此方法
  },
  methods:{
    initCourse:function () {
      let that = this
      //向后台发送ajax请求
      this.$axios.request({
        url:'http://127.0.0.1:8000/api/v1/courses/',
        method:'GET',
        responseType:'json',
      }).then(function (arg) {
        //成功之后
        console.log(arg);
        if (arg.data.code == 1000){
          //更新数据
          that.courseList = arg.data.data;
        }else {
          //弹出错误
          alert(arg.data.error);
        }

      }).catch(function (err) {
        //发生错误
        console.log(err);
      })
    }
  },
}
</script>

<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped>
h1, h2 {
  font-weight: normal;
}
ul {
  list-style-type: none;
  padding: 0;
}
li {
  display: inline-block;
  margin: 0 10px;
}
a {
  color: #42b983;
}
</style>

View Code

刷新网页，效果如下：

第二种

使用自定义中间件

修改views目录下的course.py，去掉headers

    def list(self, request, *args, **kwargs):
        """
        查询所有
        :param request:
        :param args:
        :param kwargs:
        :return:
        """
        queryset = models.Course.objects.all()
        serializer_class = CourseModelSerializer
        data = SerializedData(request, queryset, serializer_class).get_data()
        return Response(data)

View Code

在api目录下创建md文件夹，在里面创建cors.py

from django.utils.deprecation import MiddlewareMixin
from django.conf import settings

class CorsMiddleware(MiddlewareMixin):

    def process_response(self,request,response):
        # 设置响应头
        response['Access-Control-Allow-Origin'] = 'http://localhost:8080'
       
        return response

View Code

修改settings.py，注册自定义中间件

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',
    'api.md.cors.CorsMiddleware',
]

View Code

刷新vue页面，效果同上！

模拟复杂请求

修改HelloWorld.vue，增加登录按钮。发送固定的用户名和密码，指定数据格式为json

<template>
  <div class="hello">
    <h1>{{ msg }}</h1>
    <button v-on:click="doLogin">登录</button>
    <h1>课程列表</h1>
    <ul v-for="item in courseList">
      <li>{{item.name}}</li>
    </ul>
  </div>
</template>

<script>
export default {
  name: 'HelloWorld',
  data () {
    return {
      msg: '欢迎使用路飞学城',
      courseList:[],
    }
  },
  mounted(){  //页面加载完成后
    this.initCourse();  //执行此方法
  },
  methods:{
    initCourse:function () {
      let that = this
      //向后台发送ajax请求
      this.$axios.request({
        url:'http://127.0.0.1:8000/api/v1/courses/',
        method:'GET',
        responseType:'json',
      }).then(function (arg) {
        //成功之后
        console.log(arg);
        if (arg.data.code == 1000){
          //更新数据
          that.courseList = arg.data.data;
        }else {
          //弹出错误
          alert(arg.data.error);
        }

      }).catch(function (err) {
        //发生错误
        console.log(err);
      })
    },
    doLogin(){
      this.$axios.request({
        url:'http://127.0.0.1:8000/api/v1/auth/',
        method:'POST',
        data:{
          //用户名和密码
          user:'xiao',
          pwd:'123',
        },
        //增加headers头
        headers:{
          //指定数据格式
          'Content-Type':'application/json',
        },
        //响应格式为json
        responseType:'json',
      }).then(function (arg) {
        //成功之后
        console.log(arg);
      }).catch(function (err) {
        //发生错误
        console.log(err);
      })
    }
  },
}
</script>

<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped>
h1, h2 {
  font-weight: normal;
}
ul {
  list-style-type: none;
  padding: 0;
}
li {
  display: inline-block;
  margin: 0 10px;
}
a {
  color: #42b983;
}
</style>

View Code

修改api_urls.py，增加路径

from django.conf.urls import url
from api.views import course,auth

urlpatterns = [
    url(r'auth/$', auth.AuthView.as_view({'post': 'login'})),
    url(r'courses/$', course.CoursesView.as_view({'get': 'list', 'post': 'create'})),
    url(r'courses/(?P<pk>d+)/$', course.CoursesView.as_view({'get': 'retrieve', 'put': 'update', 'delete': 'destroy'}))
]

View Code

在views目录下，创建文件auth.py

from rest_framework.views import APIView
from rest_framework.viewsets import ViewSetMixin
from rest_framework.response import Response

from api import models
from api.serializers.course import CourseModelSerializer

from api.utils.response import BaseResponse
from api.utils.serialization_general import SerializedData


class AuthView(ViewSetMixin,APIView):
    def login(self, request, *args, **kwargs):
        print('用户发了POST请求了',request)
        return Response({'code':'ok'})

View Code

刷新vue页面，点击登录

查看Console，提示对方不允许

查看Network，它是一个OPTIONS请求

查看Pycharm控制台输出：

[18/Aug/2018 21:37:04] "OPTIONS /api/v1/auth/ HTTP/1.1" 200 163

通过以上信息，可以看出。浏览器发送OPTIONS请求，也就是在预检。但是后端没有同意，所以浏览器没有发送POST请求。

怎么才能让它通过预检呢？

修改md目录下的cors，做一个if判断，允许一下！

from django.utils.deprecation import MiddlewareMixin
from django.conf import settings

class CorsMiddleware(MiddlewareMixin):

    def process_response(self,request,response):
        # 设置响应头
        response['Access-Control-Allow-Origin'] = 'http://localhost:8080'
        # 当为OPTIONS时
        if request.method == "OPTIONS":
            # 允许通过的请求方式
            response["Access-Control-Allow-Methods"] = "POST,PUT,DELETE"
            # 允许通过的请求头
            response["Access-Control-Allow-Headers"] = "Content-Type"
            
        return response

View Code

刷新页面，再次点击登录

查看Console，发现请求正常

查看Network，发现有2次请求

查看第一个请求，它是OPTIONS请求方式

查看第二个请求，它是POST请求方式

查看Pycharm控制台输出：

[18/Aug/2018 21:43:24] "GET /api/v1/courses/ HTTP/1.1" 200 394
[18/Aug/2018 21:43:32] "OPTIONS /api/v1/auth/ HTTP/1.1" 200 163
用户发了POST请求了 <rest_framework.request.Request object at 0x0000024630CD85C0>
[18/Aug/2018 21:43:32] "POST /api/v1/auth/ HTTP/1.1" 200 13

通过以上信息，可以看到。数据接收正常！

通过这样，无论是简单，还是复杂，都允许。

django cors组件

CORS，全称为跨域资源共享。它允许 Web 应用服务器进行跨域访问控制，从而使跨域数据传输得以安全进行。

上面的cors.py，帮我们实现了cors。这个手写的，但是官方提供了cors组件，专门用来解决跨域问题的！

1.安装django-cors-headers

pip install django-cors-headers

2.配置settings.py文件

INSTALLED_APPS = [
    ...
    'corsheaders',  # 注册应用cors
 ] 

MIDDLEWARE_CLASSES = (
    ...
    'corsheaders.middleware.CorsMiddleware', # 注册组件cors

)
#跨域增加忽略
CORS_ALLOW_CREDENTIALS = True
CORS_ORIGIN_ALLOW_ALL = True
CORS_ORIGIN_WHITELIST = (
    '*'
)

CORS_ALLOW_METHODS = (
    'DELETE',
    'GET',
    'OPTIONS',
    'PATCH',
    'POST',
    'PUT',
    'VIEW',
)

CORS_ALLOW_HEADERS = (
    'XMLHttpRequest',
    'X_FILENAME',
    'accept-encoding',
    'authorization',
    'content-type',
    'dnt',
    'origin',
    'user-agent',
    'x-csrftoken',
    'x-requested-with',
    'Pragma',
)

View Code

注释掉自定义组件，settings.py完整代码如下：

"""
Django settings for s11luffycity project.

Generated by 'django-admin startproject' using Django 1.11.

For more information on this file, see
https://docs.djangoproject.com/en/1.11/topics/settings/

For the full list of settings and their values, see
https://docs.djangoproject.com/en/1.11/ref/settings/
"""

import os

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/1.11/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = '-i@r%a=tf*0n6!kzd=m#gx9g82i7@!x=n9jx=jta&(7%zw67#!'

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = []


# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'api.apps.ApiConfig',
    'rest_framework',
    'corsheaders',  # 注册应用cors
]

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',
    # 'api.md.cors.CorsMiddleware',
    'corsheaders.middleware.CorsMiddleware',  # 注册组件cors
]

ROOT_URLCONF = 's11luffycity.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [os.path.join(BASE_DIR, 'templates')]
        ,
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 's11luffycity.wsgi.application'


# Database
# https://docs.djangoproject.com/en/1.11/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}


# Password validation
# https://docs.djangoproject.com/en/1.11/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/1.11/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/1.11/howto/static-files/

STATIC_URL = '/static/'
REST_FRAMEWORK = {
    'DEFAULT_VERSIONING_CLASS':'rest_framework.versioning.URLPathVersioning',
    'VERSION_PARAM':'version',
    'DEFAULT_VERSION':'v1',
    'ALLOWED_VERSIONS':['v1','v2'],
    'PAGE_SIZE':20,
    'DEFAULT_PAGINATION_CLASS': 'rest_framework.pagination.PageNumberPagination',
}

#跨域增加忽略
CORS_ALLOW_CREDENTIALS = True
CORS_ORIGIN_ALLOW_ALL = True
CORS_ORIGIN_WHITELIST = (
    '*'
)

CORS_ALLOW_METHODS = (
    'DELETE',
    'GET',
    'OPTIONS',
    'PATCH',
    'POST',
    'PUT',
    'VIEW',
)

CORS_ALLOW_HEADERS = (
    'XMLHttpRequest',
    'X_FILENAME',
    'accept-encoding',
    'authorization',
    'content-type',
    'dnt',
    'origin',
    'user-agent',
    'x-csrftoken',
    'x-requested-with',
    'Pragma',
)

View Code

重启django项目，刷新页面，重启登录。效果同上！

OK！问题解决！

本文参考：

https://blog.csdn.net/apple9005/article/details/54427902