rest_framework初识
在开发过程中，通常会进行前后端分离设计，这样不仅有助于加快前后端的开发速度，降低前后端代码的耦合度，还有利于提高后端代码的适用性，比如一个API接口可以同时供web端和app端进行使用。首先了解python中API开发，python中的API主要有两种视图的处理：
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FBV：Function base view（基于函数的视图）
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CBV：Function base view（基于类的视图）
CBV：基于反射实现，根据请求方式的不同，执行不同的方法：get,post,put,delete等
一、restful 规范
随着代码编写，逐渐形成了一种大家公认的，比较合理的接口开发和命名规范，这种规范就被称为restful风格。是建议在开发的过程中遵守restful接口规范，但并不是强制要求。restful接口规范主要有以下10种。
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普通接口，用用户管理示例，需要四个接口：
def get_user(request): pass def add_user(request): pass def put_user(request): pass def delete_user(request): pass使用restful风格，一个接口处理一条数据：
def users(request): uses_list = ["柚子", "西瓜"] if request.method == "GET": pass elif request.method == "POST": pass elif request.method == "PUT": pass elif request.method == "DELETE": pass return HttpResponse(json.dumps(uses_list)) -
url中带上api进行区分
www.youzi.com/api/ -
版本
www.youzi.com/api/v1 -
路径
url尽量使用名词：
www.youzi.com/api/v1/user -
method
- GET:从服务器获取资源
- POST:在服务器新建一个资源
- PUT：更新全部资源
- PATCH:更新部分资源
- DELETE：删除资源
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过滤
www.youzi.com/api/v1/user/limit=10www.youzi.com/api/v1/user/offsey=10www.youzi.com/api/v1/user/type=1
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状态码
状态码 说明 200 成功 201 用户新建或修改数据成功(POST/PUT/PATCH) 202 Accepted，表示异步任务已经进入后台排队 204 用户删除数据成功(DELETE) 301 一次重定向 302 永久重定向 401 没有权限 403 有权限，但是访问禁止了，可能是没通过其他的校验，比如django的csrf 404 数据不存在 406 数据请求格式不正确，比如请求json，但是只有xml 410 用户请求的数据被永久删除，且不会再得到了 422 当创建对象时，发生校验码错误 500 服务器错误 -
错误处理
{ error:"password error" } -
返回结果
对不同的请求方式返回不同的结果，例如查看列表或者查看详情。
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在列表页返回详情页的链接
[ { "id":"1", "name":"youzi", "url":www.youzi.com/api/v1/fruit/1 }, { "id":"2", "name":"xigua", "url":www.youzi.com/api/v1/fruit/2 }, ]
二、Django rest_framework框架
RestFramework是一个能快速为我们提供API接口，方便我们编程的框架。依赖于django框架。自带很多实用的功能，并且提供了丰富的扩展性，我们可以通过重写一些方法进行二次开发。
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普通的基于类的视图
基于类的视图需要继承django.views中的View类，在urls中调用类视图的
as_view()方法，请求时首先会执行dispatch()方法，在dispatch()方法中通过getattr()进行反向映射找到要请求的方法如：get，post，put，patch等。以下是使用类视图的示例：
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views代码：
from django.views import View class TeachersView(View): """teacher view""" def dispatch(self, request, *args, **kwargs): """重写dispatch方法""" print("before") ret = super().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") -
urls代码
from django.urls import path from django.views.decorators.csrf import csrf_exempt urlpatterns = [ path('teachers/', csrf_exempt(views.TeachersView.as_view()), name="teachers") ]django.view.View中的部分源码：
class View: """ 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 kwargs.items(): setattr(self, key, value) @classonlymethod def as_view(cls, **initkwargs): """Main entry point for a request-response process.""" 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 """执行dispatch方法""" return self.dispatch(request, *args, **kwargs) '''''' 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)
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rest_framework的使用
安装：pip install reset_framework
简单示例：
from rest_framework.views import APIView # APIView继承的是django.views中的View，只是对request进行了再封装。 class TestPage(APIView): """试卷""" 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")APIView源码讲解：
APIView继承的也是django.view中的View，只是重写了
dispatch()方法，对request进行了再封装。主要有四部分的操作- 版本控制
- 验证用户是否登录
- 校验权限
- 访问频率限制
在以后逐渐讲解各部分的用法，感兴趣的可以先阅读源码。
部分源码：
class APIView(View): def dispatch(self, request, *args, **kwargs): """ `.dispatch()` is pretty much the same as Django's regular dispatch, but with extra hooks for startup, finalize, and exception handling. """ self.args = args self.kwargs = kwargs # 对原生的request进行再封装 # Request(request) # 原生的request = request._request request = self.initialize_request(request, *args, **kwargs) self.request = request self.headers = self.default_response_headers # deprecate? try: # 序列化request self.initial(request, *args, **kwargs) # Get the appropriate handler method 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 response = handler(request, *args, **kwargs) except Exception as exc: response = self.handle_exception(exc) self.response = self.finalize_response(request, response, *args, **kwargs) return self.response '''''' # 序列化数据 def initial(self, request, *args, **kwargs): """ Runs anything that needs to occur prior to calling the method handler. """ self.format_kwarg = self.get_format_suffix(**kwargs) # Perform content negotiation and store the accepted info on the request neg = self.perform_content_negotiation(request) request.accepted_renderer, request.accepted_media_type = neg # Determine the API version, if versioning is in use. # 1、版本处理 version, scheme = self.determine_version(request, *args, **kwargs) request.version, request.versioning_scheme = version, scheme # Ensure that the incoming request is permitted # 2、验证是否登录 self.perform_authentication(request) # 3、校验权限 self.check_permissions(request) # 4、限制访问频率 self.check_throttles(request)