模型基本使用

星哥玩云

发布于 2022-09-14 17:24:53

2160

发布于 2022-09-14 17:24:53

文章被收录于专栏：开源部署

一、配置django数据库

默认使用的是sqlite数据库

配置sqlite数据库代码为

DATABASES = {
    <span class="hljs-string">'default'</span>: {
        <span class="hljs-string">'ENGINE'</span>: <span class="hljs-string">'django.db.backends.sqlite3'</span>, <span class="hljs-comment"># 选择数据库引擎</span>
        <span class="hljs-string">'NAME'</span>: os.path.join(BASE_DIR, <span class="hljs-string">'db.sqlite3'</span>), <span class="hljs-comment"># 创建sqlite数据库文件位置</span>
    }
}

配置mysql数据库

DATABASES = {
    <span class="hljs-string">'default'</span>: {
        <span class="hljs-string">'ENGINE'</span>: <span class="hljs-string">'django.db.backends.mysql'</span>, <span class="hljs-comment"># 选择数据库引擎</span>
        <span class="hljs-string">'NAME'</span>: <span class="hljs-string">'lucky'</span>, <span class="hljs-comment">#数据库名称</span>
        <span class="hljs-string">'HOST'</span>: <span class="hljs-string">'127.0.0.1'</span>, <span class="hljs-comment">#主机</span>
        <span class="hljs-string">'USER'</span>: <span class="hljs-string">'lucky'</span>, <span class="hljs-comment">#用户名</span>
        <span class="hljs-string">'PASSWORD'</span>: <span class="hljs-string">'123456'</span>, <span class="hljs-comment">#密码</span>
        <span class="hljs-string">'PORT'</span>: <span class="hljs-number">3306</span>, <span class="hljs-comment">#端口</span>
    }
}

安装pymysql扩展库

pip3 install pymysql

在project的init.py文件中添加如下代码

<span class="hljs-keyword">import</span> pymysql
pymysql.install_as_MySQLdb()

python3.x使用的是pymysql模块，所以需要在project/__init.py文件中添加如上代码

二、表分析

需求： 创建用户表

一个用户表所需字段用户名密码性别年龄个人简介头像是否删除创建时间
创建模型代码位置 App->models.py
模型、属性、表之间的关联一个模型类对应数据库中的一张表一个类属性对应表中的一个字段
创建用户表模型

<span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">User</span><span class="hljs-params">(models.Model)</span>:</span>
    username = models.CharField(max_length=<span class="hljs-number">20</span>) <span class="hljs-comment"># 用户名  最大长度20</span>
    password = models.CharField(max_length=<span class="hljs-number">64</span>) <span class="hljs-comment"># 用户密码 最大长度 64</span>
    sex = models.BooleanField(default=<span class="hljs-keyword">True</span>) <span class="hljs-comment"># 性别 默认为True</span>
    age = models.IntegerField(default=<span class="hljs-number">20</span>) <span class="hljs-comment"># 年龄 默认20岁</span>
    info = models.CharField(max_length=<span class="hljs-number">100</span>,default=<span class="hljs-string">'info'</span>) <span class="hljs-comment"># 个人简介 最大长度100 默认为info</span>
    icon = models.CharField(max_length=<span class="hljs-number">60</span>,default=<span class="hljs-string">'default.jpg'</span>) <span class="hljs-comment"># 头像 最大长度为60 默认为 default.jpg</span>
    isDelete = models.BooleanField(default=<span class="hljs-keyword">False</span>) <span class="hljs-comment"># 是否删除 默认不删除</span>
    createTime = models.DateTimeField(auto_now_add=<span class="hljs-keyword">True</span>) <span class="hljs-comment"># 创建时间 默认为添加数据的时间</span>
    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">str</span><span class="hljs-params">(self)</span>:</span>  <span class="hljs-comment"># 打印时友好的输出展示</span>
        <span class="hljs-keyword">return</span> self.username
    <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Meta</span>:</span>
        db_table = <span class="hljs-string">'user'</span> <span class="hljs-comment"># 当前表名(如果不写 默认为应用名称+模型名称)</span>

三、生成数据表

修改DJango原码(注意2.2版本需要此操作)

sudo vim /usr/local/lib/python3.7/dist-packages/django/db/backends/mysql/base.py

version = Database.version_info
<span class="hljs-keyword">if</span> version &lt; (<span class="hljs-number">1</span>, <span class="hljs-number">3</span>, <span class="hljs-number">13</span>):
    <span class="hljs-keyword">raise</span> ImproperlyConfigured(<span class="hljs-string">'mysqlclient 1.3.13 or newer is required; you have %s.'</span> % Database.__version__)

更改为：

version = Database.version_info
<span class="hljs-comment"># if version &lt; (1, 3, 13):</span>
<span class="hljs-comment">#     raise ImproperlyConfigured('mysqlclient 1.3.13 or newer is required; you have %s.' % Database.__version__)</span>

sudo vim /usr/local/lib/python3.7/dist-packages/django/db/backends/mysql/operations.py

query = getattr(cursor, <span class="hljs-string">'_executed'</span>, <span class="hljs-keyword">None</span>)
<span class="hljs-keyword">if</span> query <span class="hljs-keyword">is</span> <span class="hljs-keyword">not</span> <span class="hljs-keyword">None</span>:
  query = query.decode(errors=<span class="hljs-string">'replace'</span>)
  <span class="hljs-keyword">return</span> query

更改为：

query = getattr(cursor, <span class="hljs-string">'_executed'</span>, <span class="hljs-keyword">None</span>)
<span class="hljs-keyword">if</span> query <span class="hljs-keyword">is</span> <span class="hljs-keyword">not</span> <span class="hljs-keyword">None</span>:
  query = query.encode(errors=<span class="hljs-string">'replace'</span>)
  <span class="hljs-keyword">return</span> query

生成迁移文件

python manage.py makemigrations

在’应用目录/migrations’下生成迁移文件此刻还没有同步到数据库

执行迁移

python  manage.py  migrate

使用迁移文件在数据库中生成对应的数据表此刻数据库中已经存在我们的用户表

四、测试数据库

进入到python shell进行测试 python manage.py shell
倒包

<span class="hljs-meta">&gt;&gt;&gt; </span><span class="hljs-keyword">from</span> App.models <span class="hljs-keyword">import</span> User

添加数据

<span class="hljs-meta">&gt;&gt;&gt; </span>u = User()  <span class="hljs-comment"># 实例化User模型类</span>
<span class="hljs-meta">&gt;&gt;&gt; </span>u.username = <span class="hljs-string">'lucky'</span> <span class="hljs-comment"># 添加用户名</span>
<span class="hljs-meta">&gt;&gt;&gt; </span>u.password = <span class="hljs-number">123456</span>  <span class="hljs-comment"># 添加密码</span>
<span class="hljs-meta">&gt;&gt;&gt; </span>u.sex = <span class="hljs-keyword">True</span> <span class="hljs-comment"># 添加性别</span>
<span class="hljs-meta">&gt;&gt;&gt; </span>u.age = <span class="hljs-number">18</span> <span class="hljs-comment"># 添加年龄</span>
<span class="hljs-meta">&gt;&gt;&gt; </span>u.info = <span class="hljs-string">'lucky是一个帅气的boy'</span> <span class="hljs-comment"># 添加个人简介</span>
<span class="hljs-meta">&gt;&gt;&gt; </span>u.save() <span class="hljs-comment"># 进行保存</span>

查询数据

<span class="hljs-meta">&gt;&gt;&gt; </span>u = User.objects.get(pk=<span class="hljs-number">1</span>) <span class="hljs-comment"># 查询主键为1的用户对象</span>
<span class="hljs-meta">&gt;&gt;&gt; </span>u
<span class="hljs-meta">&gt;&gt;&gt; </span>u.username

修改

<span class="hljs-meta">&gt;&gt;&gt; </span>u = User.objects.get(pk=<span class="hljs-number">1</span>)  <span class="hljs-comment"># 查询主键为1的用户对象</span>
<span class="hljs-meta">&gt;&gt;&gt; </span>u.username = <span class="hljs-string">'帅气的lucky'</span> <span class="hljs-comment"># 修改用户名为帅气的lucky</span>
<span class="hljs-meta">&gt;&gt;&gt; </span>u.save() <span class="hljs-comment"># 进行保存</span>

删除

<span class="hljs-meta">&gt;&gt;&gt; </span>u = User.objects.get(pk=<span class="hljs-number">1</span>) <span class="hljs-comment"># 查询主键为1的用户对象</span>
<span class="hljs-meta">&gt;&gt;&gt; </span>u.delete() <span class="hljs-comment"># 进行删除</span>

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