Django基础-004 上下文管理器&中间件&前端公共代码复用

一、上下文管理器

在views中重复使用的代码,可以在上下文管理器中实现

上下文管理器的处理流程如下:

1.先走完views里面的代码,将结果返回给前端

2.然后再将上下文的结果返回给前端

3.上下文只有在返回的是html的时候,才会走上下文处理器

1.1 上下文content_process.py代码

比如写一个博客,文章分类在很多方法都要查询文章分类,每次都查数据库,代码冗余很多,就可以考虑把查文章分类的方法,写到上下文管理器中

 1 from . import models
 2 
 3 def process_category(request):
 4     #统一将结果返回给前端,这里也可以判断是否需要返回给前端
 5     print('上下文管理器,自己写的')
 6     categories = models.Category.objects.all()
 7     return {'categories':categories}
 8 
 9 
10 def process_title(request):
11     web_site = models.WebSite.objects.all().first()
12     return {'web_site':web_site}

1.2 setting.py代码

在setting中配置上下文管理器

 1 TEMPLATES = [
 2     {
 3         'BACKEND': 'django.template.backends.django.DjangoTemplates',
 4         'DIRS': [os.path.join(BASE_DIR,'templates')],#指的是Django寻找html的目录
 5         'APP_DIRS': True,
 6         'OPTIONS': {
 7             'context_processors': [
 8                 'django.template.context_processors.debug',
 9                 'django.template.context_processors.request',
10                 'django.contrib.auth.context_processors.auth',
11                 'django.contrib.messages.context_processors.messages',
12                 'user.content_process.process_category',#配置上下文管理器的方法
13                 'user.content_process.process_title',
14             ],
15         },
16     },
17 ]

二、中间件

中间件可以拦截请求,返回,异常等情况

也可以用中间件来模拟mock服务

中间件的执行流程

 

2.1 middle_wares.py代码

 1 from django.http import HttpResponse
 2 from django.middleware.common import MiddlewareMixin
 3 from . import models
 4 
 5 class TestMiddleWare(MiddlewareMixin):
 6     def process_request(self,request):
 7         '''请求过来之后,先到这里'''
 8         path = request.path_info
 9         interface = models.Interface.objects.filter(path=path).first()
10         if interface:
11             return HttpResponse(interface.response)
12 
13         print('request.....')
14     def process_response(self,request,response):
15         #拦截返回的
16         print('response.....')
17         return response
18         # return HttpResponse('hhhh')
19     def process_exception(self,request,exception):
20         #拦截异常的
21         print('process_exception.....')
22         return HttpResponse('hhhh')

2.2 setting.py代码

在setting中配置中间件

 1 MIDDLEWARE = [
 2     'django.middleware.security.SecurityMiddleware',
 3     'django.contrib.sessions.middleware.SessionMiddleware',
 4     'django.middleware.common.CommonMiddleware',
 5     'django.middleware.csrf.CsrfViewMiddleware',
 6     'django.contrib.auth.middleware.AuthenticationMiddleware',
 7     'django.contrib.messages.middleware.MessageMiddleware',
 8     'django.middleware.clickjacking.XFrameOptionsMiddleware',
 9     'user.middle_wares.TestMiddleWare',#配置中间件
10 ]

2.3 中间件模拟mock服务

1.建立一张接口表

表中存有接口名称,接口路径,返回数据

2.在请求拦截器中实现

匹配接口路径,接口路径配置在接口信息表中,则直接根据数据表的返回数据字段内容返回

如果不匹配,则还是走正常流程

1     def process_request(self,request):
2         '''请求过来之后,先到这里'''
3         path = request.path_info
4         interface = models.Interface.objects.filter(path=path).first()
5         if interface:
6             return HttpResponse(interface.response)

三、前端公共代码复用

前端很多代码是一样的,怎么样实现复用

1.先建立复用代码base.html,如果这一块代码不是公共的,则预留代码块

{% block content %}
//预留代码块,content是唯一
{% endblock %}

<!doctype html>
<html lang="en">
<head>
    <!-- Required meta tags -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <meta name="referrer" content="origin">
    <!-- TDK and ICO -->
    <title>{{web_site.title}}</title>

    <meta name="description"
          content="{{web_site.desc}}">
    <meta name="keywords" content="Python自学,Python爬虫,Django博客,Python web开发,个人博客">
    <!--站长验证-->

    <link rel="shortcut icon" href="/static/blog/img/favicon.ico" type="image/x-icon"/>
    <!-- Bootstrap and font-awesome CSS -->
    <link href="https://cdn.bootcss.com/twitter-bootstrap/4.3.1/css/bootstrap.min.css" rel="stylesheet">
    <link href="https://cdn.bootcss.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet">
    <script src="/static/js/headroom.min.js"></script>
    <!-- blog CSS -->
    <link href="/static/css/base.css" rel="stylesheet">

    <!--根据cookies判断是否启用暗色主题-->


    {% block css %}

    {% endblock %}

</head>
<body>
<!--导航开始-->

<nav class="navbar navbar-expand-md bg-white fixed-top blog-navbar py-md-0">
    <a class="navbar-brand d-md-none d-lg-block" id="site-logo-name" href="/">
        <strong class="px-2">{{web_site.title}}</strong>
    </a>
    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent"
            aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
        <span class="navbar-toggler-icon"></span>
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                <a class="nav-link py-md-3 active" href="/"><i class="fa fa-home mr-1"></i>首页<span class="sr-only">(current)</span></a>
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            <form class="nav-item navbar-form mr-2 py-md-2" role="search" method="get" id="searchform"
                  action="/search/">
                <div class="input-group">
                    <input type="search" name="q" class="form-control rounded-0" placeholder="站内搜索" autocomplete="off"
                           required=True>
                    <div class="input-group-btn">
                        <button class="btn btn-info rounded-0" type="submit"><i class="fa fa-search"></i></button>
                    </div>
                </div><!-- /input-group -->
            </form>
        </ul>

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</div>

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            {% endblock %}
            <div class="col-lg-4">


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                    </div>

                    <ul class="list-group list-group-flush f-16">
                        {% for category in categories %}
                        <li class="list-group-item d-flex justify-content-between align-items-center pr-2 py-2">
                            <a class="category-item" href="/category/{{ category.id }}"
                               title="查看【{{ category.name }}】分类下所有文章">{{ category.name }}</a>
                            <span class="badge text-center" title="当前分类下有{{category.article_set.count}}篇文章">{{category.article_set.count}}</span>
                        </li>
                        {% endfor %}
                    </ul>
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base.html

2.在index.html中要复用base.html代码

先继承base.html   

{% extends 'base.html' %}

在加入不复用的代码

{% block content %}

{% endblock %}

{% extends 'base.html' %}

{% block content %}
    <div class="col-lg-8">


                <div id="carouselExampleIndicators" class="carousel slide" data-ride="carousel">
                    <ol class="carousel-indicators">


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                            <div class="text-muted mb-2 f-12">


                                <img class="avatar"
                                     src="https://tendcode.com/media/avatar/2019/07/27/91ef76c6a7efce1b99717f97a851f3deb48f6510.png"
                                     alt="Hopetree">

                                <span>Hopetree</span>
                                <span><i class="fa fa-calendar-times-o ml-2 mr-1"></i>{{article.create_time}}</span>
                            </div>
                            <h2 class="mt-0 font-weight-bold text-info f-17">
                                <a href="/article/yaml_and_jinja2/" target="_blank">{{article.title}}</a>
                            </h2>
                            <p class="d-none d-sm-block mb-2 f-15">{{article.content}}</p>

                            <div class="text-muted mb-0 f-12">
                                <a class="cate" href="/category/hello-python/" title="查看当前分类下更多文章">
                                    <i class="fa fa-book mr-1"></i>{{article.category.name}}</a>
                                <span><i class="fa fa-eye ml-2 mr-1"></i>226</span>
                                <a href="/article/yaml_and_jinja2/#comment-block" target="_blank" title="查看文章评论">
                                    <i class="fa fa-comments ml-2 mr-1"></i>8</a>
                            </div>
                        </div>
                    </div>
                    {% endfor %}





                </div>
                <div class="text-center mt-2 mt-sm-1 mt-md-0 mb-3 f-16">

                    <span class="text-secondary" title="当前页已经是首页">上一页</span>

                    <span class="mx-2">&nbsp;1&nbsp;/&nbsp;4&nbsp;</span>

                    <a class="text-success" href="?page=2">下一页</a>

                </div>
            </div>
{% endblock %}
index.html
原文地址:https://www.cnblogs.com/cjxxl1213/p/13556475.html