Django-djangorestframework-渲染模块

目录

• 渲染模块
  • 渲染模块的效果
  • 源码分析
  • 如何自定义配置使用渲染类
  • 自定义渲染模块

渲染模块

可以根据用户请求 URL 或 用户可接受的类型，筛选出合适的 渲染组件。

reponse 数据 json 与 browser 两种渲染方式

浏览器 和 Postman 请求结果渲染数据的方式不一样

# 内置渲染器
# 可以根据用户请求 URL 或 用户可接受的类型，筛选出合适的 渲染组件。
# 显示json格式：JSONRenderer
http://127.0.0.1:8000/test/?format=json
http://127.0.0.1:8000/test.json

# 默认显示格式：BrowsableAPIRenderer（可以修改它的html文件）
http://127.0.0.1:8000/test/?format=admin
http://127.0.0.1:8000/test.admin
    
# 表格方式：AdminRenderer
http://127.0.0.1:8000/test/?format=form
http://127.0.0.1:8000/test.form
        
# form表单方式：HTMLFormRenderer
http://127.0.0.1:8000/test/?format=form
http://127.0.0.1:8000/test.form

渲染模块的效果

postman 测试

浏览器渲染

未提供浏览器渲染时

源码分析

入口 dispatch 中的 self.response = self.finalize_response(request, response, *args, **kwargs)

rest_framework.views.APIView#dispatch

    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
        # 请求模块
        request = self.initialize_request(request, *args, **kwargs)
        self.request = request
        self.headers = self.default_response_headers  # deprecate?

        try:
            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)

        # 渲染模块 -- drf 渲染模块入口
        self.response = self.finalize_response(request, response, *args, **kwargs)
        return self.response

rest_framework.views.APIView#finalize_response

    def finalize_response(self, request, response, *args, **kwargs):
        """
        Returns the final response object.
        """
        # Make the error obvious if a proper response is not returned
        assert isinstance(response, HttpResponseBase), (
            'Expected a `Response`, `HttpResponse` or `HttpStreamingResponse` '
            'to be returned from the view, but received a `%s`'
            % type(response)
        )

        if isinstance(response, Response):
            if not getattr(request, 'accepted_renderer', None):
                # 获得解析类 （从这里再进入）
                neg = self.perform_content_negotiation(request, force=True)
                request.accepted_renderer, request.accepted_media_type = neg

            response.accepted_renderer = request.accepted_renderer
            response.accepted_media_type = request.accepted_media_type
            response.renderer_context = self.get_renderer_context()

        # Add new vary headers to the response instead of overwriting.
        vary_headers = self.headers.pop('Vary', None)
        if vary_headers is not None:
            patch_vary_headers(response, cc_delim_re.split(vary_headers))

        for key, value in self.headers.items():
            response[key] = value

        return response

rest_framework.views.APIView#perform_content_negotiation

    def perform_content_negotiation(self, request, force=False):
        """
        Determine which renderer and media type to use render the response.
        """
        # 后去渲染类（从这里再进入）
        renderers = self.get_renderers()
        # 得到的就是渲染类的对象
        
        conneg = self.get_content_negotiator()

        try:
            return conneg.select_renderer(request, renderers, self.format_kwarg)
        	# 在根据 request 请求的方式再选择具体是选择哪种渲染方式，然后再调用某个方法，把数据渲染成 页面 或 json
        except Exception:
            if force:
                return (renderers[0], renderers[0].media_type)
            raise

rest_framework.views.APIView#get_renderers

    def get_renderers(self):
        """
        Instantiates and returns the list of renderers that this view can use.
        """
        # self.renderer_classes，当前类对象没有该属性，去找类，在类属性中找到了
        return [renderer() for renderer in self.renderer_classes]
    	# self.renderer_classes 遍历出来是两个渲染类，类加括号会调用类的 __init__ 方法实例化

self.renderer_classes 来源

class APIView(View):
    # self.renderer_classes 取到的即是配置中的 DEFAULT_RENDERER_CLASSES
    renderer_classes = api_settings.DEFAULT_RENDERER_CLASSES

E:/python3-6-4/Lib/site-packages/rest_framework/settings.py 分析 settings 源码

"""
Settings for REST framework are all namespaced in the REST_FRAMEWORK setting.
For example your project's `settings.py` file might look like this:

REST_FRAMEWORK = {
    'DEFAULT_RENDERER_CLASSES': [
        'rest_framework.renderers.JSONRenderer',
        'rest_framework.renderers.TemplateHTMLRenderer',
    ],
    'DEFAULT_PARSER_CLASSES': [
        'rest_framework.parsers.JSONParser',
        'rest_framework.parsers.FormParser',
        'rest_framework.parsers.MultiPartParser',
    ],
}

This module provides the `api_setting` object, that is used to access
REST framework settings, checking for user settings first, then falling
back to the defaults.
"""
from django.conf import settings
from django.test.signals import setting_changed
from django.utils.module_loading import import_string

from rest_framework import ISO_8601

DEFAULTS = {
    # Base API policies
    'DEFAULT_RENDERER_CLASSES': [
        # 默认提供了这两种渲染方式
        'rest_framework.renderers.JSONRenderer',
        'rest_framework.renderers.BrowsableAPIRenderer',
    ],
    # ...
}
    # ...

如何自定义配置使用渲染类

得知我们可以在自己的 settings 文件中这样来配置它的解析类（全局配置）

REST_FRAMEWORK = {
    'DEFAULT_RENDERER_CLASSES': [  # 全局配置的解析方式，所有视图类都会受这个影响
        'rest_framework.renderers.JSONRenderer',
        'rest_framework.renderers.BrowsableAPIRenderer',  # 这个是给浏览器渲染用的，没有时浏览器渲染会报错
    ],
}

• 在 settings.py 中配置 DEFAULT_RENDERER_CLASSES 完成的是全局配置，所有接口统一处理

• 如果只有部分接口要做特殊化处理，可以使用局部配置

  # 写成类属性就可以变成局部配置了
  from rest_framework.renders import JSONRenderer
  	
  class Test2(APIView):
  	renderer_classes = [JSONRenderer,]  # 必须是以一个可迭代类型（for ... 遍历它了）
      
  	def get(self, request, *args, **kwargs):
  		return Response("drf get ok 2")
  	
  	def post(self, request, *args, **kwargs):
  		return Response("drf post ok 2")
  

查找顺序：自定义视图类（局部） => APIView 视图类 => 自定义 drf 配置（全局） => drf 默认配置

自定义渲染模块

视图类

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')

aa.html

<!DOCTYPE html>
<html lang="en">
<head>
    
    <title>Title</title>
</head>
<body>
{{ title }}
{{ publishDate }}
</body>
</html>