-
Notifications
You must be signed in to change notification settings - Fork 1
/
Copy pathDjango抽象类.html
118 lines (103 loc) · 5.84 KB
/
Django抽象类.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>商伟的技术博客</title>
<meta name="description" content="">
<meta name="author" content="商伟">
<!-- HTML5 shim, for IE6-8 support of HTML elements -->
<!--[if lt IE 9]>
<script src="/theme/html5.js"></script>
<![endif]-->
<!-- Styles -->
<link href="/theme/bootstrap.min.css" rel="stylesheet">
<link href="/theme/local.css" rel="stylesheet">
<link href="/theme/pygments.css" rel="stylesheet">
<!-- Feeds -->
</head>
<body>
<div class="topbar">
<div class="topbar-inner">
<div class="container-fluid">
<a class="brand" href="/">商伟的技术博客</a>
<ul class="nav">
<li class="active"><a href="/category/django.html">Django</a></li>
<li ><a href="/category/docker.html">Docker</a></li>
<li ><a href="/category/git.html">GIT</a></li>
<li ><a href="/category/javascript.html">JavaScript</a></li>
<li ><a href="/category/mongodb.html">Mongodb</a></li>
<li ><a href="/category/mysql.html">MySQL</a></li>
<li ><a href="/category/pa-chong.html">爬虫</a></li>
<li ><a href="/category/python.html">Python</a></li>
<li ><a href="/category/rabbitmq.html">RabbitMQ</a></li>
<li ><a href="/category/redis.html">redis</a></li>
<li ><a href="/category/shu-ju-jie-gou.html">数据结构</a></li>
<li ><a href="/category/sui-shou-bi-ji.html">随手笔记</a></li>
<li ><a href="/category/supervisor.html">Supervisor</a></li>
<li ><a href="/category/vue.html">VUE</a></li>
<li ><a href="/category/wang-luo.html">网络</a></li>
<li ><a href="/category/web.html">web</a></li>
<li ><a href="/category/xiao-cheng-xu.html">小程序</a></li>
<li ><a href="/category/xu-ni-huan-jing.html">虚拟环境</a></li>
</ul>
<p class="pull-right"><a href="/archives.html">[archives]</a> <a href="/tags.html">[tags]</a></p>
</div>
</div>
</div>
<div class="container-fluid">
<div class="sidebar">
<div class="well">
<h3>Blogroll</h3>
<ul>
<li><a href="http://getpelican.com/">Pelican</a></li>
<li><a href="http://python.org/">Python.org</a></li>
<li><a href="http://jinja.pocoo.org/">Jinja2</a></li>
</ul>
<div class="social">
<h3>Social</h3>
<ul>
<li><a href="https://lienze.tech/">老渔夫吃虾米</a></li>
</ul>
</div>
</div>
</div>
<div class="content">
<div class='article'>
<div class="page-header"><h1>Django抽象类</h1></div>
<div class="well small">Permalink: <a class="more" href="/Django抽象类.html">2019-08-08 18:44:00+02:00</a>
by <a class="url fn" href="/author/shang-wei.html">商伟 </a>
in <a href="/category/django.html">Django</a>
tags: <a href="/tag/django.html">Django</a> </div>
<div><h1>abstract</h1>
<p>这个属性是定义当前的模型类是不是一个抽象类。所谓抽象类是不会对应数据库表的。一般我们用它来归纳一些公共属性字段，然后继承它的子类可以继承这些字段。比如下面的代码中Base是一个抽象类，Usermodel是一个继承了Base的子类，那么在运行生成命令时，不会生成Base表，但是会生成一个Usermodel表，它包含了Base中继承来的字段，以后如果再添加一个Kecheng模型类，它可以同样继承Base的公共属性：</p>
<div class="highlight"><pre><span></span><span class="c1"># 抽象类</span>
<span class="k">class</span> <span class="n">Base</span>(<span class="n">models</span>.<span class="n">Model</span>):
<span class="n">create_date</span> = <span class="n">models</span>.<span class="n">DateTimeField</span>(<span class="n">auto_now</span>=<span class="nb">True</span>)
<span class="n">update_date</span> = <span class="n">models</span>.<span class="n">DateTimeField</span>(<span class="n">auto_now_add</span>=<span class="nb">True</span>)
<span class="k">class</span> <span class="n">Meta:</span>
<span class="n">abstract</span> = <span class="nb">True</span>
<span class="c1"># 用户表</span>
<span class="k">class</span> <span class="n">Usermodel</span>(<span class="n">Base</span>):
<span class="nb">name</span> = <span class="n">models</span>.<span class="n">CharField</span>(<span class="n">max_length</span>=<span class="mi">32</span>)
<span class="n">pwd</span> = <span class="n">models</span>.<span class="n">CharField</span>(<span class="n">max_length</span>=<span class="mi">255</span>)
<span class="c1"># 课程表</span>
<span class="k">class</span> <span class="n">Kecheng</span>(<span class="n">Base</span>):
<span class="nb">name</span> = <span class="n">models</span>.<span class="n">CharField</span>(<span class="n">max_length</span>=<span class="mi">32</span>)
<span class="n">price</span> = <span class="n">models</span>.<span class="n">DecimalField</span>(<span class="n">max_digits</span>=<span class="mi">10</span>,<span class="n">decimal_places</span>=<span class="mi">2</span>)
<span class="c1"># 学生表</span>
<span class="k">class</span> <span class="n">Stu</span>(<span class="n">Base</span>):
<span class="nb">name</span> = <span class="n">models</span>.<span class="n">CharField</span>(<span class="n">max_length</span>=<span class="mi">32</span>)
<span class="n">img</span> = <span class="n">models</span>.<span class="n">CharField</span>(<span class="n">max_length</span>=<span class="mi">255</span>)
<span class="n">kecheng</span> = <span class="n">models</span>.<span class="n">ManyToManyField</span>(<span class="nb">to</span>=<span class="s">'Kecheng'</span>)
</pre></div>
<h1>总结</h1>
<h3>抽象类不会生成一个表，但是可以让别的模型去继承他，继承抽象类里面的所有字段</h3></div>
</div>
<footer>
<p>Powered by <a href="http://getpelican.com/">Pelican</a>. Theme based on <a href="http://twitter.github.com/bootstrap/">Twitter Bootstrap</a>.</p>
<p>© 商伟</p>
</footer>
</div>
</div>
</body>
</html>