DRF(一)

http协议
    应用层协议
    请求与响应规范：首行 - 头 - 体
    特点：无状态、无连接、请求永远是客户端到服务器端、ssl
    
wsgi协议
    原生django启动项目 - 启动了server socket - wsgiref - uWSGI(项目上线)
    规定数据的解析方式：
        get数据、post数据(数据数据) => request => 回调的视图函数
        返回响应对象 - HTTPResponse类对象 - 数据、响应状态码

url链接：http://api.oldboy.com/login/
请求方式：get | post | put ...
请求参数：username | password
响应结果：result | data

method: GET
url: https://api.map.baidu.com/place/v2/search
params:
    ak: 6E823f587c95f0148c19993539b99295
    region: 上海
    query: 肯德基
    output: json

models.py

  from django.db import models
  class Book(models.Model):
     name = models.CharField(max_length=64)
     price = models.DecimalField(max_digits=5, decimal_places=2)
     class Meta:
        db_table = ‘old_boy_book‘
        verbose_name = ‘书籍‘
        verbose_name_plural = verbose_name
     def __str__(self):
        return self.name

class User(models.Model):
    SEX_CHOICES = [
        (0, ‘男‘),
        (1, ‘女‘),
        (2, ‘哇塞‘)
    ]
    username = models.CharField(max_length=64)
    password = models.CharField(max_length=64)
    sex = models.IntegerField(choices=SEX_CHOICES, default=0)
    # 需要配置media工作目录与路由
    icon = models.ImageField(upload_to=‘icon‘, default=‘/icon/default.png‘)
    class Meta:
        db_table = ‘old_boy_user‘
        verbose_name = ‘用户‘
        verbose_name_plural = verbose_name

    def __str__(self):
        return self.username

创建Django项目并设置默认app名为api，完成路由分发:


# 主路由
from django.conf.urls import url, include
from django.contrib import admin
urlpatterns = [
    url(r‘^admin/‘, admin.site.urls),
    url(r‘^api/‘, include(‘api.urls‘)),
]

# api应用下的子路由
from django.conf.urls import url
from . import views
urlpatterns = [
    # as_view() 本质拿到 view函数地址，
    # view内部通过dispatch分发请求给具体的(get|post|delete)方法处理请求
    # 处理完后的响应结果会一层层返回
    url(r‘^books/$‘, views.BookView.as_view()),
    url(r‘^books/(?P<pk>.*)/$‘, views.BookView.as_view()),
]

数据库迁移:

>: python manage.py makemigrations
>: python manage.py migrate

后台管理:

from django.contrib import admin
from . import models
admin.site.register(models.Book)
admin.site.register(models.User)

# 创建超级用户
# >: python manage.py createsuperuser

views.py

from django.views import View
from django.http import JsonResponse
from . import models
class BookView(View):
    def get(self, request, *args, **kwargs):
        pk = kwargs.get(‘pk‘)
        if pk:  # 通过是否有主键决定获取单个或是全部资源
            book_dic_list = models.Book.objects.filter(pk=pk).values(‘name‘, ‘price‘)
            if not book_dic_list:
                return JsonResponse({
                    ‘status‘: 2,
                    ‘msg‘: ‘pk值有误‘,
                    ‘results‘: {}
                })
            return JsonResponse({
                ‘status‘: 0,
                ‘msg‘: ‘ok‘,
                ‘results‘: book_dic_list[0]
            })

        book_dic_list = models.Book.objects.all().values(‘name‘, ‘price‘)
        if not book_dic_list:
            return JsonResponse({
                ‘status‘: 2,
                ‘msg‘: ‘无数据‘,
                ‘results‘: {}
            })
        return JsonResponse({
            ‘status‘: 0,
            ‘msg‘: ‘ok‘,
            ‘results‘: list(book_dic_list)
        })

##### media工作目录：settings.py

```python
# MEDIA_URL = ‘/media/‘
MEDIA_ROOT = os.path.join(BASE_DIR, ‘media‘)
```

##### 路由：主urls.py

```python
from django.conf.urls import url, include
from django.contrib import admin

from django.views.static import serve
from django.conf import settings
urlpatterns = [
    url(r‘^admin/‘, admin.site.urls),
    url(r‘^api/‘, include(‘api.urls‘)),
    url(r‘^media/(?P<path>.*)‘, serve, {‘document_root‘: settings.MEDIA_ROOT})
]
```

1）一般都采用安全协议(接口都是操作数据的)：https

2）体现接口的关键字：api
    https://api.oldboy.com
    https://www.oldboy.com/api

3）接口操作的数据称之为资源：采用资源名称的复数
    https://api.oldboy.com/books/
    https://api.oldboy.com/users/

4）接口链接中不出现操作资源的动词，通过请求方式来决定操作资源的动作
    https://api.oldboy.com/books/
    get：获取所有 | post：增加一个 
    https://api.oldboy.com/books/(?P<pk>)/
    get：获取一个 | put：整体修改一个(patch：局部修改一个) | delet：删除一个

5）资源数据有多版本时，接口可以做版本控制
    https://api.oldboy.com/books/v1/
    https://api.oldboy.com/v2/books/
    
6）资源响应的限制条件：筛选、排序、限制...
    https://api.oldboy.com/books/?publish=1&ordering=-price&limit=3
    
7）响应状态码
    网络状态码：2xx | 3xx | 4xx | 5xx
    数据状态码(约定的)：0 | 1 | 2
    {
        ‘status‘: 1,
    }
    -- SUCCESS(0, "查询成功")
    -- NODATA(1, "非正确，无数据，显示基本信息")
    -- FEAILED(2, "查询失败")

8）响应结果的信息描述：
    {
        ‘status‘: 1,
        ‘msg‘: ‘login failed‘
    }

9）响应的结果：get所有：所有资源 | get一个：一个资源 | post、put、patch：新增、修改的资源 | delete：不做任何返回
    {
        ‘status‘: 0,
        ‘msg‘: ‘ok‘,
        ‘results‘: [登录的用户对象序列化结果]
    }
    
10）响应结果中有二次资源(用户头像：图片链接，用户详情：详情接口)
    要表明请求二次资源的接口

注：通过 接口文档 告诉前台传递的必要和选填参数

pip3 install djangorestframework

# 注册drf app
NSTALLED_APPS = [
    # ...
    ‘rest_framework‘,
]

# 具体功能在具体模块下
from rest_framework.request import Request
from rest_framework.response import Response
from rest_framework.exceptions import APIException
from rest_framework.filters import OrderingFilter
from rest_framework.views import APIView
from rest_framework.pagination import PageNumberPagination
from rest_framework.settings import APISettings

# 自定义drf配置 - 在自己的settings.py
REST_FRAMEWORK = {
    # 自定义修改drf的配置们
}

 url(r‘^books/‘, views.Books.as_view()),

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

       request = self.initialize_request(request, *args, **kwargs)

# 入口：APIView类的dispatch函数
self.response = self.finalize_response(request, response, *args, **kwargs)
->
neg = self.perform_content_negotiation(request, force=True)
->
renderers = self.get_renderers()
->
self.renderer_classes
->
APISetting：DEFAULT_RENDERER_CLASSES

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

from rest_framework.renderers import JSONRenderer
from rest_framework.renderers import BrowsableAPIRenderer
class UserAPIView(APIView):
    # 局部配置：只有该视图类起作用
    renderer_classes = [JSONRenderer]  # 只提供JSON数据渲染
    pass

# drf配置
REST_FRAMEWORK = {
    # 响应的渲染模块
    ‘DEFAULT_RENDERER_CLASSES‘: [
        ‘rest_framework.renderers.JSONRenderer‘,
        ‘rest_framework.renderers.BrowsableAPIRenderer‘,
    ],
}

# 入口：APIView类的dispatch函数
request = self.initialize_request(request, *args, **kwargs)
->
parsers=self.get_parsers()
->
self.parser_classes
->
APISetting：DEFAULT_PARSER_CLASSES

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

from rest_framework.parsers import JSONParser
from rest_framework.parsers import FormParser
from rest_framework.parsers import MultiPartParser
class UserAPIView(APIView):
    # 局部配置：只有该视图类起作用
    parser_classes = [JSONParser]  # 只提供JSON解析
    pass

# drf配置
REST_FRAMEWORK = {
    # 响应的渲染模块
    ‘DEFAULT_RENDERER_CLASSES‘: [
        ‘rest_framework.renderers.JSONRenderer‘,
        ‘rest_framework.renderers.BrowsableAPIRenderer‘,
    ],
    # 请求数据解析模块
    ‘DEFAULT_PARSER_CLASSES‘: [
        ‘rest_framework.parsers.JSONParser‘,  # ‘application/json‘
        ‘rest_framework.parsers.FormParser‘,  # ‘application/x-www-form-urlencoded‘
        ‘rest_framework.parsers.MultiPartParser‘  # multipart/form-data
    ],
}

 请求的数据包：均解析到 request.data 中
 请求的?文件参数(get请求url拼接参数)：均解析到 request.query_params 中

# 响应可以设置响应数据、响应网络状态码、响应头、响应数据类型等
data = {
    ‘status‘: 0,
    ‘msg‘: ‘get ok‘,
    ‘results‘: [],
    ‘token‘: ‘123.12321.231‘
}
return Response(
    data=data,
    status=status.HTTP_200_OK,
    headers={‘Token‘: ‘123as.masd21.asd213sd‘},
    content_type=‘application/json‘  # 默认就是application/json
)