rest_framework框架

回顾CBV

　　什么是CBV

　　CBV(class base  view),基于类的视图编程方式，即在view.py文件中使用类的方式为API接口书写对应的视图。与CBV对应的是FBV(function base view)，基于函数的视图编程方式。

　　CBV的简单示例

# 路由部分
from django.conf.urls import url,include
from . import views

urlpatterns = [
    url(r'^book/$',views.BookSerializers.as_view()),
]

# 视图部分
class BookSerializers(View):

    def get(self,request):
        return HttpResponse("GET")

    def post(self,request):
        return HttpResponse("POST")

　　

代码分析

as_view部分

 @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
            #为捕获到异常，最后实际上就是执行dispatch()方法
            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                    

dispatch部分

    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.
　　　　　　#根据请求的方法遍历http_method_names进行匹配,匹配成功返回子类的请求方法的方法名，供路由去执行该方法

        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)

rest_framework

什么是rest_framework

　　是一个前后端分离的框架系统，使前、后端开发着可以脱离对方的工作，从而只考虑自己业务内容的代码逻辑的一个框架。

get方法代码示例

from django.shortcuts import render,HttpResponse
from django.views import View
from . import models
# Create your views here.

"""
    使用CBV的方式进行视图编程
"""

from rest_framework import serializers


# 仿照form的思想，组装成Serializers的数据形式，为后面的序列化类最准备
class BookSerializers(serializers.Serializer):
        title=serializers.CharField(max_length=32)
        price=serializers.IntegerField()
        pub_date=serializers.DateField()
        #  一对多字段，source定义关联表的具体字段
        publish=serializers.CharField(source="publish.pk")
        # 多对多字段，采用自定义方法的方式定义显示的字段
        authors = serializers.SerializerMethodField()

        #  自定义函数名= get_ + authors,ob代表当前的book对象
        def get_authors(self,obj):
            temp=[]
            for author in obj.authors.all():
                temp.append({"pk":author.pk,"name":author.name})
            return temp


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


"""
    功能：
        向客户端返回http请求
    知识点:
        使用rest_framework组件，返回http请求，必须要继承 rest_framework的 APIView，不再继承Django的View
"""
class BookView(APIView):

    def get(self,request):
        # 拿到一个QuerySet对象，包含着所有的book对象
        book_query = models.Book.objects.all()
        """
            功能：
                声明要对哪些对象的哪些字段进行序列化
            参数说明：
                当只是对一个对象进行序列话的时候，many=FALSE，但是对多个对象进行序列化的时候需要many=True
        """
        response = BookSerializers(book_query,many=True)
        # 序列化的结果保存在data方法中
        # 使用rest_framework的serializers进行序列化之后的json字符串，需要用Response方法返回
        return Response(response.data)

对于 BookSerializers 类可以改变继承的类，减少代码

"""
    方式二：
        继承serializers.ModelSerializer类，组装数据格式。
        与ModelForm做类比
"""
class BookSerializers(serializers.ModelSerializer):
    class Meta:
        model=models.Book
        fields="__all__"

    authors = serializers.SerializerMethodField()
    def get_authors(self,obj):
        temp=[]
        for author in obj.authors.all():
            temp.append({"pk":author.pk,"name":author.name})
        return temp