RESTFULL 07 rest-framework分页器，相应器，解析器，url控制器，版本控制

rest-framework分页器，相应器，解析器，url控制器，版本控制

一、分页器

1、简单分页（查看第n页，每页显示n条）

from rest_framework.pagination import PageNumberPagination
# 一 基本使用：url=url=http://127.0.0.1:8000/pager/?page=2&size=3，size无效
class  Pager(APIView):
    def get(self,request,*args,**kwargs):
        # 获取所有数据
        ret=models.Book.objects.all()
        # 创建分页对象
        page=PageNumberPagination()
        # 在数据库中获取分页的数据
        page_list=page.paginate_queryset(ret,request,view=self)
        # 对分页进行序列化
        ser=BookSerializer1(instance=page_list,many=True)
        return Response(ser.data)
# 二 自定制 url=http://127.0.0.1:8000/pager/?page=2&size=3
# size=30，无效，最多5条
class Mypage(PageNumberPagination):
    page_size = 2
    page_query_param = 'page'
    # 定制传参
    page_size_query_param = 'size'
    # 最大一页的数据
    max_page_size = 5
class  Pager(APIView):
    def get(self,request,*args,**kwargs):
        # 获取所有数据
        ret=models.Book.objects.all()
        # 创建分页对象
        page=Mypage()
        # 在数据库中获取分页的数据
        page_list=page.paginate_queryset(ret,request,view=self)
        # 对分页进行序列化
        ser=BookSerializer1(instance=page_list,many=True)
        # return Response(ser.data)
        # 这个也是返回Response对象，但是比基本的多了上一页，下一页，和总数据条数（了解即可）
        return page.get_paginated_response(ser.data)

setting里

REST_FRAMEWORK = {
    # 每页显示两条
    'PAGE_SIZE':2
}

路由：

url(r'^pager/$', views.Pager.as_view()),

Serializers

class BookSerializer1(serializers.ModelSerializer):
    class Meta:
        model=models.Book
        # fields="__all__"
        exclude=('authors',)

使用方法：

• 1 导入PageNumberPagination类
• 2 实例化产生一个对象
  page_pagination = PageNumberPagination()
• 3 需要配置四个参数:page_size,page_query_param,page_size_query_param,max_page_size
  page_size必须指定:在setting中指定或者直接赋值
• 4 调用下面的方法,返回ret数据
  ret = page_pagination.paginate_queryset(book_list, request, self)
• 5 再序列化,就是序列化返回的数据,也就是ret

类中需要掌握的几个属性

-page_size:控制每页显示条数
-page_query_param:控制查询第几页的查询参数,
-比如page_query_param='xx'
-http://127.0.0.1:8000/books/?xx=2  表示查询第二页的数据
-page_size_query_param:控制每页最大显示的条数
-比如page_pagination.page_size_query_param='max'
-http://127.0.0.1:8000/books/?xx=2&max=6   表示查询第二页的数据,每页显示6条
-max_page_size:控制每页最大显示的条数
-比如:page_pagination.max_page_size=7
-http://127.0.0.1:8000/books/?max=1000    最多显示7条

2、偏移分页（在第n个位置，向后查看n条数据）

使用方式:

​ 同简单分页

重点的参数：

-default_limit:默认每页显示的条数,默认偏移的数量
-比如:default_limit=5
-http://127.0.0.1:8000/books/    就会显示5条数据
-limit_query_param:往后偏移多少条
-就用默认值:limit
-offset_query_param:标杆值
-用默认值:offset
limit_query_param+offset_query_param联合起来用:
-访问:http://127.0.0.1:8000/books/?limit=1&offset=5  表示:以数据的第5条作为标杆,往后偏移1条
-max_limit:最大偏移的条数(最大取出的条数)

# http://127.0.0.1:8000/pager/?offset=4&limit=3
from rest_framework.pagination import LimitOffsetPagination
# 也可以自定制，同简单分页
class  Pager(APIView):
    def get(self,request,*args,**kwargs):
        # 获取所有数据
        ret=models.Book.objects.all()
        # 创建分页对象
        page=LimitOffsetPagination()
        # 在数据库中获取分页的数据
        page_list=page.paginate_queryset(ret,request,view=self)
        # 对分页进行序列化
        ser=BookSerializer1(instance=page_list,many=True)
        # return page.get_paginated_response(ser.data)
        return Response(ser.data)

3、 CursorPagination（加密分页，只能看上一页和下一页，速度快）

重点参数:

-page_size:每页显示的条数
-cursor_query_param:不需要动
-ordering:按什么排序

通过get_paginated_response返回结果中带上一页和下一页的链接地址

page_pagination.get_paginated_response(book_ser.data) 方法的用法

from rest_framework.pagination import CursorPagination
# 看源码，是通过sql查询，大于id和小于id
class  Pager(APIView):
    def get(self,request,*args,**kwargs):
        # 获取所有数据
        ret=models.Book.objects.all()
        # 创建分页对象
        page=CursorPagination()
        page.ordering='nid'
        # 在数据库中获取分页的数据
        page_list=page.paginate_queryset(ret,request,view=self)
        # 对分页进行序列化
        ser=BookSerializer1(instance=page_list,many=True)
        # 可以避免页码被猜到
        return page.get_paginated_response(ser.data)

二、url控制器

1、自定义路由

from django.conf.urls import url
from app01 import views
urlpatterns = [
    url(r'^books/$', views.BookView.as_view()),
    url(r'^books/(?P<pk>d+)$', views.BookDetailView.as_view()),
]

class BookView(APIView):

    def get(self, request):
        book_list = models.Book.objects.all()
        bs = BookSerializers(book_list, many=True)
        return Response(bs.data)

    def post(self, request):
        # 添加一条数据
        print(request.data)

        bs=BookSerializers(data=request.data)
        if bs.is_valid():
            bs.save()  # 生成记录
            return Response(bs.data)
        else:

            return Response(bs.errors)

class BookDetailView(APIView):
    def get(self,request,pk):
        book_obj=models.Book.objects.filter(pk=pk).first()
        bs=BookSerializers(book_obj,many=False)
        return Response(bs.data)
    def put(self,request,pk):
        book_obj = models.Book.objects.filter(pk=pk).first()

        bs=BookSerializers(data=request.data,instance=book_obj)
        if bs.is_valid():
            bs.save() # update
            return Response(bs.data)
        else:
            return Response(bs.errors)
    def delete(self,request,pk):
        models.Book.objects.filter(pk=pk).delete()

        return Response("")

2、半自动路由（试图类继承ModelViewSet）

from django.conf.urls import url
from app01 import views
urlpatterns = [
    url(r'^publish/$', views.PublishView.as_view({'get':'list','post':'create'})),
    url(r'^publish/(?P<pk>d+)/$', views.PublishView.as_view({'get':'retrieve','put':'update','delete':'destroy'})),

]

from rest_framework.viewsets import ModelViewSet
class PublishView(ModelViewSet):
    queryset=models.Publish.objects.all()
    serializer_class=PublishSerializers

3、全自动路由（自动路由生成）

from django.conf.urls import url,include
from app01 import views
from rest_framework import routers
#生成一个router对象
router=routers.DefaultRouter()
# 两个参数，一个是匹配的路由，一个是视图中写的CBV的类
router.register('publish',views.PublishView)
urlpatterns = [
    # http://127.0.0.1:8000/publish/format=json(渲染器通过这个判断，返回渲染的页面)
    # url(r'^publish/', views.PublishView.as_view({'get':'list','post':'create'})),
    # http://127.0.0.1:8000/publish.json(渲染器通过这个判断，返回渲染的页面)
    # url(r'^publish.(?P<format>w+)$', views.PublishView.as_view({'get':'list','post':'create'})),
    
    # 可以用 以下方式访问
    # 1 http://127.0.0.1:8000/publish/
    # 2 http://127.0.0.1:8000/publish.json
    # 3 http://127.0.0.1:8000/publish/3
    # 4 http://127.0.0.1:8000/publish/3.json   
    url(r'',include(router.urls))
]

from rest_framework.viewsets import ModelViewSet
class PublishView(ModelViewSet):
    queryset=models.Publish.objects.all()
    serializer_class=PublishSerializers

三、响应器

1、 作用

根据 用户请求URL 或 用户可接受的类型，筛选出合适的 渲染组件。
用户请求URL：
http://127.0.0.1:8000/test/?format=json
http://127.0.0.1:8000/test.json

2、 内置渲染器

显示json格式：JSONRenderer

访问URL：

• http://127.0.0.1:8000/test/?format=json
• http://127.0.0.1:8000/test.json
• http://127.0.0.1:8000/test/

默认显示格式：BrowsableAPIRenderer（可以修改它的html文件）

访问URL：

• http://127.0.0.1:8000/test/?format=api
• http://127.0.0.1:8000/test.api
• http://127.0.0.1:8000/test/

表格方式：AdminRenderer

访问URL：

• http://127.0.0.1:8000/test/?format=admin
• http://127.0.0.1:8000/test.admin
• http://127.0.0.1:8000/test/

form表单方式：HTMLFormRenderer

访问URL：

• http://127.0.0.1:8000/test/?format=form
• http://127.0.0.1:8000/test.form
• http://127.0.0.1:8000/test/

3、局部使用

from rest_framework.renderers import  HTMLFormRenderer,BrowsableAPIRenderer
class BookDetailView(APIView):
    renderer_classes = [HTMLFormRenderer,BrowsableAPIRenderer ]
    def get(self,request,pk):
        book_obj=models.Book.objects.filter(pk=pk).first()
        bs=BookSerializers(book_obj,many=False)
        return Response(bs.data)
    def put(self,request,pk):
        book_obj = models.Book.objects.filter(pk=pk).first()
        bs=BookSerializers(data=request.data,instance=book_obj)
    	if bs.is_valid():
        	bs.save() # update
        	return Response(bs.data)
   	 	else:
        	return Response(bs.errors)
	def delete(self,request,pk):
    	models.Book.objects.filter(pk=pk).delete()

    	return Response("")

4、全局使用

settings里配置：

REST_FRAMEWORK = {
    'DEFAULT_RENDERER_CLASSES':['rest_framework.renderers.JSONRenderer']
}

5、自定义显示模版

from rest_framework.renderers import  TemplateHTMLRenderer
class BookDetailView(APIView):
    renderer_classes = [TemplateHTMLRenderer]
    def get(self,request,pk):
        book_obj=models.Book.objects.filter(pk=pk).first()
        bs=BookSerializers(book_obj,many=False)
        return Response(bs.data,template_name='aa.html')

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
{{ title }}
{{ publishDate }}
</body>
</html>

注意：如果同时多个存在时，自动根据URL后缀来选择渲染器。

四、解析器

1、解析器的作用

根据请求头 content-type 选择对应的解析器对请求体内容进行处理。

有application/json，x-www-form-urlencoded，form-data等格式

2、全局使用解析器

setting里

REST_FRAMEWORK = {
    'DEFAULT_PARSER_CLASSES':[
        'rest_framework.parsers.JSONParser'
        'rest_framework.parsers.FormParser'
        'rest_framework.parsers.MultiPartParser'
    ]

}

路由：

urlpatterns = [
    url(r'test/', TestView.as_view()),
]

视图函数：

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

class TestView(APIView):
    def post(self, request, *args, **kwargs):
        print(request.content_type)

        # 获取请求的值，并使用对应的JSONParser进行处理
        print(request.data)
        # application/x-www-form-urlencoded 或 multipart/form-data时，request.POST中才有值
        print(request.POST)
        print(request.FILES)
        return Response('POST请求，响应内容')

    def put(self, request, *args, **kwargs):
        return Response('PUT请求，响应内容')

3、局部使用解析器

a. 仅处理请求头content-type为application/json的请求体

from django.conf.urls import url, include
from web.views.s5_parser import TestView

urlpatterns = [
    url(r'test/', TestView.as_view(), name='test'),
]

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework.request import Request
from rest_framework.parsers import JSONParser


class TestView(APIView):
    parser_classes = [JSONParser, ]

    def post(self, request, *args, **kwargs):
        print(request.content_type)

        # 获取请求的值，并使用对应的JSONParser进行处理
        print(request.data)

        # application/x-www-form-urlencoded 或 multipart/form-data时，request.POST中才有值
        print(request.POST)
        print(request.FILES)

        return Response('POST请求，响应内容')

    def put(self, request, *args, **kwargs):
        return Response('PUT请求，响应内容')

b. 仅处理请求头content-type为application/x-www-form-urlencoded 的请求体

from django.conf.urls import url, include
from web.views import TestView

urlpatterns = [
    url(r'test/', TestView.as_view(), name='test'),
]

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework.request import Request
from rest_framework.parsers import FormParser


class TestView(APIView):
    parser_classes = [FormParser, ]

    def post(self, request, *args, **kwargs):
        print(request.content_type)

        # 获取请求的值，并使用对应的JSONParser进行处理
        print(request.data)

        # application/x-www-form-urlencoded 或 multipart/form-data时，request.POST中才有值
        print(request.POST)
        print(request.FILES)

        return Response('POST请求，响应内容')

    def put(self, request, *args, **kwargs):
        return Response('PUT请求，响应内容')

c. 仅处理请求头content-type为multipart/form-data的请求体

from django.conf.urls import url, include
from web.views import TestView

urlpatterns = [
    url(r'test/', TestView.as_view(), name='test'),
]

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework.request import Request
from rest_framework.parsers import MultiPartParser


class TestView(APIView):
    parser_classes = [MultiPartParser, ]

    def post(self, request, *args, **kwargs):
        print(request.content_type)

        # 获取请求的值，并使用对应的JSONParser进行处理
        print(request.data)
        # application/x-www-form-urlencoded 或 multipart/form-data时，request.POST中才有值
        print(request.POST)
        print(request.FILES)
        return Response('POST请求，响应内容')

    def put(self, request, *args, **kwargs):
        return Response('PUT请求，响应内容')

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="http://127.0.0.1:8000/test/" method="post" enctype="multipart/form-data">
    <input type="text" name="user" />
    <input type="file" name="img">

    <input type="submit" value="提交">

</form>
</body>
</html>

d. 仅上传文件

from django.conf.urls import url, include
from web.views import TestView

urlpatterns = [
    url(r'test/(?P<filename>[^/]+)', TestView.as_view(), name='test'),
]

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework.request import Request
from rest_framework.parsers import FileUploadParser


class TestView(APIView):
    parser_classes = [FileUploadParser, ]

    def post(self, request, filename, *args, **kwargs):
        print(filename)
        print(request.content_type)

        # 获取请求的值，并使用对应的JSONParser进行处理
        print(request.data)
        # application/x-www-form-urlencoded 或 multipart/form-data时，request.POST中才有值
        print(request.POST)
        print(request.FILES)
        return Response('POST请求，响应内容')

    def put(self, request, *args, **kwargs):
        return Response('PUT请求，响应内容')

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="http://127.0.0.1:8000/test/f1.numbers" method="post" enctype="multipart/form-data">
    <input type="text" name="user" />
    <input type="file" name="img">

    <input type="submit" value="提交">

</form>
</body>
</html>

e. 同时多个Parser

当同时使用多个parser时，rest framework会根据请求头content-type自动进行比对，并使用对应parser

from django.conf.urls import url, include
from web.views import TestView

urlpatterns = [
    url(r'test/', TestView.as_view(), name='test'),
]

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework.request import Request
from rest_framework.parsers import JSONParser, FormParser, MultiPartParser


class TestView(APIView):
    parser_classes = [JSONParser, FormParser, MultiPartParser, ]

    def post(self, request, *args, **kwargs):
        print(request.content_type)

        # 获取请求的值，并使用对应的JSONParser进行处理
        print(request.data)
        # application/x-www-form-urlencoded 或 multipart/form-data时，request.POST中才有值
        print(request.POST)
        print(request.FILES)
        return Response('POST请求，响应内容')

    def put(self, request, *args, **kwargs):
        return Response('PUT请求，响应内容')

4、源码分析

1 在调用request.data时，才进行解析，由此入手
    @property
    def data(self):
        if not _hasattr(self, '_full_data'):
            self._load_data_and_files()
        return self._full_data
        
2 查看self._load_data_and_files()方法---->self._data, self._files = self._parse()

        def _parse(self):
            #用户请求头里content_type的值
            media_type = self.content_type

            #self.parsers 就是用户配置的parser_classes = [FileUploadParser,FormParser ]
            #self里就有content_type，传入此函数
            parser = self.negotiator.select_parser(self, self.parsers)

3 查看self.negotiator.select_parser(self, self.parsers)
     def select_parser(self, request, parsers):
        #同过media_type和request.content_type比较，来返回解析器，然后调用解析器的解析方法
        #每个解析器都有media_type = 'multipart/form-data'属性
        for parser in parsers:
            if media_type_matches(parser.media_type, request.content_type):
                return parser
        return None
    
4 最终调用parser的解析方法来解析parsed = parser.parse(stream, media_type, self.parser_context)

1 Request实例化，parsers=self.get_parsers()
    Request(
                request,
                parsers=self.get_parsers(),
                authenticators=self.get_authenticators(),
                negotiator=self.get_content_negotiator(),
                parser_context=parser_context
            )
2 get_parsers方法，循环实例化出self.parser_classes中类对象
    def get_parsers(self):
        return [parser() for parser in self.parser_classes]            

3 self.parser_classes 先从类本身找，找不到去父类找即APIVIew 中的
    parser_classes = api_settings.DEFAULT_PARSER_CLASSES
4 api_settings是一个对象，对象里找DEFAULT_PARSER_CLASSES属性，找不到，会到getattr方法
        def __getattr__(self, attr):
            if attr not in self.defaults:
                raise AttributeError("Invalid API setting: '%s'" % attr)

            try:
                #调用self.user_settings方法，返回一个字典，字典再取attr属性
                val = self.user_settings[attr]
            except KeyError:
                # Fall back to defaults
                val = self.defaults[attr]

            # Coerce import strings into classes
            if attr in self.import_strings:
                val = perform_import(val, attr)

            # Cache the result
            self._cached_attrs.add(attr)
            setattr(self, attr, val)
            return val
 5 user_settings方法 ，通过反射去setting配置文件里找REST_FRAMEWORK属性，找不到，返回空字典
    @property
    def user_settings(self):
        if not hasattr(self, '_user_settings'):
            self._user_settings = getattr(settings, 'REST_FRAMEWORK', {})
        return self._user_settings