Mikowoo007

Django--(2)模型(Model)属性与参数整理

模型

模型类属性命名限制：

不能是python的保留关键字
不能使用连续的下划线. 这是由django的查询方式决定的
定义属性时需要指定字段类型. 通过字段类型的参数指定选项. 语法如下：属性名=models.字段类型(选项)

文件app/models.py 模板格式

from django.db import models
class ModelName(models.Model):  # 模型类
	Field1 = models.XXXField(...)
	Field2 = models.XXXField(...)
	...
	class Meta:  #元选项
		db_table = ...
		other_metas = ...

模型类

每个模型类都可以被映射为数据库中的一个数据表，类类属性被映射为数据字段，除此之外，数据库表的主键、外键、约束等也通过类属性完成定义

模型类属性

属性	描述
`AutoField`	一个自动递增的整型字段，添加记录时会自动增长 AutoField 字段通常会用于充当数据表的主键若模型没有指定主键字段，则Django 自动添加一个 AutoField字段
`IntegerField`	用于保存一个整数
`SmallIntegerField`	类似于 IntegerField 但只具有较小的输入范围，具体范围依赖于所使用的数据库
`BigIntegerField`	64位整型字段
`BinaryField`	二进制数据字段只能通过 types 对其赋值
`FloatField`	浮点型字段定义本字段时必须传入 `max_digits` 和`decimal_places` 参数用于定义总位数(不包括小数点和符号)和小数位数
`DecimalField`	十进制浮点数 `max_digits`参数表示总位 `decimal_places` 参数表示小数位数
`CommaSeparatedIntegerField`	用于存放逗号分隔的整数值相较与普通的 CharField, 它有特殊的表单数据验证要求
`DurationField`	存储时间周期，用 Python 的 timedelta 类型构建
`EmailField`	一个带检查 Email 合法性的CharField
`FileField`	一个文件上传字段在定义本字段时传入参数 `upload_to`,用于保存上载文件的服务器文件系统路径这个路径必须包含 striftime formatting, 该格式将上载文件的 date/time 替换
`FilePathField`	按目录限制规则选择文件定义本字段必须传入参数 `path` ，用于限制目录
`ImageField`	类似于 FileField,同时验证上传对象是否是一个合法的图片有两个可选参数 `height_field` 和 `width_field` 如果提供这两个参数，则图片将按照提供的高度和宽度规格保存该字段要求安装 Python Imaging 库
`IPAddressField`	一个字符串形式的IP地址例如: 192.23.250.2
`NullBooleanField`	类似于 BooleanField, 但比其多一个None选项
`PhoneNumberField`	带有美国风格的电话号码校验的 CharField 格式为 XXX-XXX-XXXX
`SlugField`	只包含字母、数字、下划线和连字符的输入字段通常用于URL
`URL`	用于保存URL
`USStateField`	美国州名的缩写字段，由两个字母组成
`XMLField`	XML字段是具有XML合法验证的TextField

属性	描述	相对应的HTML标签
`BooleanField`	布尔字段
`CharField`	字符串字段，用于较短的字符串	单行输入
`TextField`	大容量文本字段	多行编辑框 </code></td> </tr> <tr> <td align="left"><code>DateField</code></td> <td>日期字段</td> <td><code><input type="text"></code>、一个JavaScript 日期和一个“today” 快捷按键 <br> 有两个额外可选参数： <br> <code>auto_now</code> 当对象被保存时，将该字段的值设置为当前时间 <br> <code>auto_now_add</code> 当对象被首次创建时，将该字段的值设置为当前时间</td> </tr> <tr> <td align="left"><code>DateTimeField</code></td> <td>类似于 DateField,但同时支持于时间的输入</td> <td></td> </tr> <tr> <td align="left"><code>TimeField</code></td> <td>时间字段，类似于 DateTimeField <br> 但只能表达和输入时间</td> <td></td> </tr> </tbody> </table> <h4>模型类属性参数</h4> <table> <thead> <tr> <th>参数</th> <th>描述</th> </tr> </thead> <tbody> <tr> <td>max_length</td> <td>定义字符的长度 <br> 例如： <code>headline = models.CharField(max_length=255)</code></td> </tr> <tr> <td>primary_key</td> <td>设置一个模型的主键字段 <br> 例如：<code>primary_key=true</code></td> </tr> <tr> <td>null</td> <td>定义是否允许相对应的数据库字段为Null, <br>默认设置为 False <br> 是一个数据库中的非空约束</td> </tr> <tr> <td>blank</td> <td>定义字段是否可以为空 <br> blank 用于字段的HTML表单验证，即判断用户是否可以不输入数据</td> </tr> <tr> <td>choices</td> <td>定义字段的可选值 <br> 本字段的值应该是一个包含二维元素的元组 <br> 元组的每个元素的第一个值是实际存储的值, <br>第二个值是HTML页面进行选择时显示的值</td> </tr> <tr> <td>default</td> <td>设置默认值 <br> 例如: <code>default="please input here"</code></td> </tr> <tr> <td>help_text</td> <td>HTML页面中输入控件的帮助字符串</td> </tr> <tr> <td>unique</td> <td>是否为字段定义数据库的唯一约束</td> </tr> <tr> <td>无名参数</td> <td>可以设置该字段在HTML页面中的人性化名称例如：<br> <code>level = models.CharField("请为本条信息评级",max_length=1,choices=LEVELS)</code> <br> 如果不设置本参数，则字段本身将被显示在 HTML 页面中作为输入提示</td> </tr> <tr> <td>db_index</td> <td>若值为True，则在表中会为此字段创建索引 <br> 默认False</td> </tr> <tr> <td>db_column</td> <td>字段的名称 <br> 如果未指定，则使用属性的名称</td> </tr> </tbody> </table> <h3>元选项 (Meta类)</h3> <p>通过此类可以定义模型元数据，比如：数据库表名，数据默认排序方式等</p> <table> <thead> <tr> <th align="left">属性</th> <th>描述</th> </tr> </thead> <tbody> <tr> <td align="left"><code>abstract:</code></td> <td>标识本类是否为抽象基类 <br> True or False</td> </tr> <tr> <td align="left"><code>app_label:</code></td> <td>定义本类所属的应用</td> </tr> <tr> <td align="left"><code>db_table:</code></td> <td>映射的数据库表名，例如： db_table=‘moments’ <br> 如果在Meta中不提供 db_table 字段，则Django 会为模型自动生成数据表名，生成的格式为“应用名_模型名”,例如：应用app的模型 Comment 的默认数据表名为 app_comment</td> </tr> <tr> <td align="left"><code>db_tablespace:</code></td> <td>映射的表空间名称 <br> 表空间的概念只在某些数据库如 Oracle 中存在，不存在表空间的概念的数据库将忽略此字段</td> </tr> <tr> <td align="left"><code>default_related_name:</code></td> <td>定义本模型的反向关系引用名称，默认与模型名一致</td> </tr> <tr> <td align="left"><code>get_latest_by:</code></td> <td>定义按哪个字段值排列以获得模型的开始或结束记录 <br> 本属性值通常指向一个日期或整型的模型字段</td> </tr> <tr> <td align="left"><code>managed:</code></td> <td>True or False <br> 定义 Django的 manage.py 命令行工具是否管理本模型。<br> 默认为 True，若将其设置为 False，则运行 <code>python manage.py migrate</code> 时将不会在数据库中生成本模型的数据表，所以需要手工维护数据库的定义</td> </tr> <tr> <td align="left"><code>order_with_respect_to:</code></td> <td>定义本模型可以按照某外键引用的关系排序</td> </tr> <tr> <td align="left"><code>order:</code></td> <td>本模型记录的默认排序字段，可以设置多个字段，默认以升序排列，<br> 若以降序排列则表示要在字段名前加负号("-") <br> 例如：定义 user_name 字段升序和 pub_date 降序排列 <br> <code>order = ['user_name','-pub_date']</code></td> </tr> <tr> <td align="left"><code>dafault_permissions:</code></td> <td>模型操作权限 <br> 默认为 <code>default_permisstions=('add','change','delete')</code></td> </tr> <tr> <td align="left"><code>proxy"=:</code></td> <td>True or False <br> 本模型及所有继承自本模型的子模型是否为代理模型</td> </tr> <tr> <td align="left"><code>required_db_features:</code></td> <td>定义底层数据库所必须具备的特性 <br> 例如：<code>required_db_features=['gis_enabled']</code>只将本数据模型生成在满足 gis_enabled 特性的数据库中</td> </tr> <tr> <td align="left"><code>required_db_vendor:</code></td> <td>定义底层数据库类型 <br> 比如 SQLite,PostgreSQL,MySQL,Oracle <br> 如果定义了本属性，则模型只能在其声明的数据库中被维护</td> </tr> <tr> <td align="left"><code>unique_together:</code></td> <td>用来设置的不重复的字段组合，必须唯一(可以将多个字段做联合唯一)<br> 例如：<code>unique_together = (("user_name","pub_date"),)</code> <br> 定义了每个 user_name 在同一个 pub_date 中只能有一条数据表记录 <br> 因为 unique_together 本身是一个元组，所以可以设置多个这样的唯一约束</td> </tr> <tr> <td align="left"><code>index_together:</code></td> <td>定义联合索引的字段，可以设置多个 <br> 例如：<code>index_together = [["pub_date","deadline"],]</code></td> </tr> <tr> <td align="left"><code>verbose_name:</code></td> <td>指明一个易于理解和表述的单数形式的对象名称。如果这个值没有被设置，则Django将会使用该model的类型的分词形式作为它的对象表述名，即 CamelCase 将会被转换为camel case</td> </tr> <tr> <td align="left"><code>verbose_name_plural:</code></td> <td>指明一个易于理解和表述的复数形式的对象名称</td> </tr> </tbody> </table> <p>修改默认生成的表名，</p> <pre><code class="prism language-python"><span class="token comment">#-- coding:utf-8 --</span> <span class="token keyword">from</span> django<span class="token punctuation">.</span>db <span class="token keyword">import</span> models <span class="token comment"># Create your models here.</span> <span class="token comment">#------------- 一对多 ----------------------</span> <span class="token comment">#图书类</span> <span class="token keyword">class</span> <span class="token class-name">BookInfo</span><span class="token punctuation">(</span>models<span class="token punctuation">.</span>Model<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token triple-quoted-string string">'''图书模型类'''</span> <span class="token comment">#id 自动生成</span> <span class="token comment">#图书名称</span> btitle <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token comment">#出版日期</span> bpub_date <span class="token operator">=</span> models<span class="token punctuation">.</span>DateField<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment">#阅读量</span> bread <span class="token operator">=</span> models<span class="token punctuation">.</span>IntegerField<span class="token punctuation">(</span>default<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">)</span> <span class="token comment">#评论量</span> bcomment <span class="token operator">=</span> models<span class="token punctuation">.</span>IntegerField<span class="token punctuation">(</span>default<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">)</span> <span class="token comment">#删除标记</span> isDelete <span class="token operator">=</span> models<span class="token punctuation">.</span>BooleanField<span class="token punctuation">(</span>default<span class="token operator">=</span><span class="token boolean">False</span><span class="token punctuation">)</span> <span class="token keyword">def</span> <span class="token function">__str__</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token comment"># 返回书名</span> <span class="token keyword">return</span> self<span class="token punctuation">.</span>btitle <span class="token keyword">class</span> <span class="token class-name">Meta</span><span class="token punctuation">:</span> db_table <span class="token operator">=</span> <span class="token string">'bookinfo'</span> <span class="token comment">#指定模型类对应的表明</span> </code></pre> <h3>通过模型操作数据库</h3> <h4>查询</h4> <p><code>模型类.objects.属性</code></p> <table> <thead> <tr> <th>函数名</th> <th>功能</th> <th>返回值</th> <th>说明</th> </tr> </thead> <tbody> <tr> <td><code>get</code></td> <td>返回表中满足条件的<mark>一条且只能有一条数据</mark></td> <td>返回值是一个模型类对象</td> <td>参数中写查询条件<br> 1. 如果查到多条数据，则抛异常<code>MultipleObjectsReturned</code> <br>2. 查询不到数据，则抛异常：<code>DoesNotExist</code></td> </tr> <tr> <td><code>all</code></td> <td>返回模型类对应表格中的所有数据</td> <td>返回值是QuerySet类型</td> <td>查询集</td> </tr> <tr> <td><code>filter</code></td> <td>返回满足条件的数据</td> <td>返回值是QuerySet类型</td> <td>参数写查询条件</td> </tr> <tr> <td><code>exclude</code></td> <td>返回不满足条件的数据</td> <td>返回值是QuerySet类型</td> <td>参数写查询条件</td> </tr> <tr> <td><code>order_by</code></td> <td>对查询结果进行排序</td> <td>返回值是QuerySet类型</td> <td>参数中写根据哪些字段进行排序 <br> 降序：字段前加 ‘-’号</td> </tr> </tbody> </table> <p>练习与演示<br> 准备练习数据集：使用博客 Django_182_入门指南图书数据表进行练习<br> <a href="http://img.e-com-net.com/image/info8/59fd7ac5d27e4b06beaaa33f0ac92dcd.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/59fd7ac5d27e4b06beaaa33f0ac92dcd.jpg" alt="Django--(2)模型(Model)属性与参数整理_第1张图片" width="650" height="191" style="border:1px solid black;"></a><br> 查询集<br> <code>all</code>, <code>filter</code>, <code>exclude</code>, <code>order_by</code>调用这些函数会产生一个查询集，<code>QuerySet类对象</code>可以继续调用上面的所有函数<br> 查询集特性</p> <ol> <li>惰性查询：<br> 只有在实际使用查询集中的数据的时候才会发生对数据库的真正查询</li> <li>缓存：<br> 当使用的是同一个查询集时，第一次使用的时候会发生实际数据库的查询，然后把结果缓存起来，之后再使用这个查询集时，使用的是缓存中的结果</li> </ol> <p>限制查询集<br> 3. 可以对一个查询集进行<mark>取下标或者切片</mark>操作来限制查询集的结果, <mark>下标不允许为负数</mark><br> 4. 对一个查询集进行切片操作会<mark>产生一个新的查询集</mark></p> <p>取出查询集的数据</p> <table> <thead> <tr> <th>方法</th> <th>说明</th> </tr> </thead> <tbody> <tr> <td><code>b[0]</code></td> <td>如果b[0]不存在，抛异常:<code>IndexError</code></td> </tr> <tr> <td><code>b[0:1].get()</code></td> <td>如果<code>b[0:1].get()</code>不存在，抛异常:<code>DoesNotExist</code></td> </tr> </tbody> </table> <p><code>exists()</code> 函数判断一个查询集是否有数据，返回 True,False</p> <p><a href="http://img.e-com-net.com/image/info8/f4be89fe8a56499ab35762b08299c46e.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/f4be89fe8a56499ab35762b08299c46e.jpg" alt="Django--(2)模型(Model)属性与参数整理_第2张图片" width="538" height="389" style="border:1px solid black;"></a></p> <h5>get</h5> <p>查询有id=5的数据</p> <pre><code class="prism language-python">book <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span>get<span class="token punctuation">(</span><span class="token builtin">id</span><span class="token operator">=</span><span class="token number">5</span><span class="token punctuation">)</span> </code></pre> <p>等效</p> <pre><code class="prism language-python">book <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span>get<span class="token punctuation">(</span>id__exact<span class="token operator">=</span><span class="token number">5</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/0f3f92db3ca64cd8b3963dd0de550c8f.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/0f3f92db3ca64cd8b3963dd0de550c8f.jpg" alt="Django--(2)模型(Model)属性与参数整理_第3张图片" width="650" height="141" style="border:1px solid black;"></a><br> <a href="http://img.e-com-net.com/image/info8/2907bd87f7e14ab49911d0752b7d20d6.png" target="_blank"><img src="http://img.e-com-net.com/image/info8/2907bd87f7e14ab49911d0752b7d20d6.png" alt="在这里插入图片描述" width="548" height="79"></a><br> 使用查询的id号没有数据，抛的异常<br> <a href="http://img.e-com-net.com/image/info8/70386a2efcfe4936947a50e263cbabd8.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/70386a2efcfe4936947a50e263cbabd8.jpg" alt="Django--(2)模型(Model)属性与参数整理_第4张图片" width="650" height="105" style="border:1px solid black;"></a><br> 使用get查询出多个数据，抛出异常<br> <a href="http://img.e-com-net.com/image/info8/2967334033a74a408dd50981d98d8527.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/2967334033a74a408dd50981d98d8527.jpg" alt="Django--(2)模型(Model)属性与参数整理_第5张图片" width="650" height="107" style="border:1px solid black;"></a></p> <h5>all</h5> <p><a href="http://img.e-com-net.com/image/info8/ff5e0fa7f42d4549b10b696f578de42a.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/ff5e0fa7f42d4549b10b696f578de42a.jpg" alt="Django--(2)模型(Model)属性与参数整理_第6张图片" width="520" height="328" style="border:1px solid black;"></a></p> <h5>filter,get,exclude 参数的使用格式</h5> <p>参数格式 <code>模型属性名__条件名=值</code></p> <h6><mark>判等条件</mark> 条件名：<code>exact</code></h6> <p>查询 id=5 的数据</p> <pre><code class="prism language-python">book <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span>get<span class="token punctuation">(</span>id__exact<span class="token operator">=</span><span class="token number">5</span><span class="token punctuation">)</span> </code></pre> <p>查询 isDelete=0 的数据</p> <pre><code class="prism language-python"> books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>isDelete__exact<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/e05d851b777d451280c85872bb763795.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/e05d851b777d451280c85872bb763795.jpg" alt="Django--(2)模型(Model)属性与参数整理_第7张图片" width="650" height="244" style="border:1px solid black;"></a></p> <h6><mark>模糊查询</mark></h6> <p>条件名 <code>contains</code> 包含<br> 查询书名包含 “传” 的图书</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>btitle__contains<span class="token operator">=</span><span class="token string">'传'</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/5b98f469d2f24cbca475b672a2d5b312.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/5b98f469d2f24cbca475b672a2d5b312.jpg" alt="Django--(2)模型(Model)属性与参数整理_第8张图片" width="650" height="119" style="border:1px solid black;"></a><br> 条件名 <code>endswith</code> 以…结尾<br> 查询以 “部” 结尾的图书</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>btitle__endswith<span class="token operator">=</span><span class="token string">'部'</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/3f4be939367f48068dd5d3c0e3065a8b.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/3f4be939367f48068dd5d3c0e3065a8b.jpg" alt="Django--(2)模型(Model)属性与参数整理_第9张图片" width="650" height="115" style="border:1px solid black;"></a><br> 条件名 <code>startswith</code> 以…开头<br> 查询以“流” 开头的图书</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>btitle__startswith<span class="token operator">=</span><span class="token string">'流'</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/d8c800bf8f464c68956b3d6d8ee43ca4.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/d8c800bf8f464c68956b3d6d8ee43ca4.jpg" alt="Django--(2)模型(Model)属性与参数整理_第10张图片" width="650" height="129" style="border:1px solid black;"></a></p> <h6>空查询 isnull</h6> <p>查询图书名 <mark>不为空</mark> 的图书</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>btitle__isnull<span class="token operator">=</span><span class="token boolean">False</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/2b68a4b0cc404d1a89bab10d19d4e086.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/2b68a4b0cc404d1a89bab10d19d4e086.jpg" alt="Django--(2)模型(Model)属性与参数整理_第11张图片" width="650" height="230" style="border:1px solid black;"></a><br> 查询图书名 <mark>为空</mark> 的图书</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>btitle__isnull<span class="token operator">=</span><span class="token boolean">True</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/10091a1c1c7142e3a996fbe8ca6e06e0.png" target="_blank"><img src="http://img.e-com-net.com/image/info8/10091a1c1c7142e3a996fbe8ca6e06e0.png" alt="Django--(2)模型(Model)属性与参数整理_第12张图片" width="686" height="107" style="border:1px solid black;"></a></p> <h6>范围查询 in</h6> <p>查询 id 为 5,7,17 中图书</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>id__in <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">5</span><span class="token punctuation">,</span><span class="token number">7</span><span class="token punctuation">,</span><span class="token number">17</span><span class="token punctuation">]</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/7394ddf4e64943b4b639f931ab15e3a0.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/7394ddf4e64943b4b639f931ab15e3a0.jpg" alt="Django--(2)模型(Model)属性与参数整理_第13张图片" width="650" height="177" style="border:1px solid black;"></a></p> <h6>比较查询</h6> <p><code>gt</code> (great than) 大于<br> <code>lt</code> (less than) 小于<br> <code>gte</code> (great than equal) 大于等于<br> <code>lte</code> (less than equal) 小于等于<br> 查询 id>0 的图书</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>id__gt <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/f581cc2fee9c47b4b56868f043bf0a2c.png" target="_blank"><img src="http://img.e-com-net.com/image/info8/f581cc2fee9c47b4b56868f043bf0a2c.png" alt="Django--(2)模型(Model)属性与参数整理_第14张图片" width="597" height="156" style="border:1px solid black;"></a></p> <h6>日期查询</h6> <p>条件名 <code>year</code> 年<br> 查询 1980 年发表的图书</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>bpub_date__year<span class="token operator">=</span><span class="token number">1980</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/d161167c133642ac8ea320f27e847037.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/d161167c133642ac8ea320f27e847037.jpg" alt="Django--(2)模型(Model)属性与参数整理_第15张图片" width="650" height="123" style="border:1px solid black;"></a><br> 条件名 <code>month</code> 月<br> 查询 11月发表的图书</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>bpub_date__month<span class="token operator">=</span><span class="token number">11</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/69adf7b15ce243a0859e90fcc453cd0d.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/69adf7b15ce243a0859e90fcc453cd0d.jpg" alt="Django--(2)模型(Model)属性与参数整理_第16张图片" width="650" height="125" style="border:1px solid black;"></a><br> 查询 1980-1-1 之后发表的图书</p> <pre><code class="prism language-python"><span class="token keyword">from</span> datetime <span class="token keyword">import</span> date books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>bpub_date__gt<span class="token operator">=</span>date<span class="token punctuation">(</span><span class="token number">1980</span><span class="token punctuation">,</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/fc58a9a1b8f340a4bc1a4dc63abaa4cf.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/fc58a9a1b8f340a4bc1a4dc63abaa4cf.jpg" alt="Django--(2)模型(Model)属性与参数整理_第17张图片" width="650" height="221" style="border:1px solid black;"></a></p> <h5>exclude 不等于</h5> <p>查询 id 不等于 5 的数据</p> <pre><code class="prism language-python"> books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span>exclude<span class="token punctuation">(</span><span class="token builtin">id</span><span class="token operator">=</span><span class="token number">5</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/9141775ad723458097ceb521adb4d5c4.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/9141775ad723458097ceb521adb4d5c4.jpg" alt="Django--(2)模型(Model)属性与参数整理_第18张图片" width="545" height="228" style="border:1px solid black;"></a></p> <h5>order_by 排序</h5> <p>查询所有图书的信息，按照 id 从小到大进行排序</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">all</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span>order_by<span class="token punctuation">(</span><span class="token string">'id'</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/369caf633a2f4628bcf8594bfd61578e.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/369caf633a2f4628bcf8594bfd61578e.jpg" alt="Django--(2)模型(Model)属性与参数整理_第19张图片" width="621" height="245" style="border:1px solid black;"></a></p> <p>查询所有图书的信息，按照 id 从大到小进行排序</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">all</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span>order_by<span class="token punctuation">(</span><span class="token string">'-id'</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/b9ed8d6fe6d049d6adf265be89f15441.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/b9ed8d6fe6d049d6adf265be89f15441.jpg" alt="Django--(2)模型(Model)属性与参数整理_第20张图片" width="612" height="250" style="border:1px solid black;"></a><br> 把 id>3 的图书信息按照阅读量从大到小排序显示</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>id__gt<span class="token operator">=</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">.</span>order_by<span class="token punctuation">(</span><span class="token string">'-bread'</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/dcd15105d4cc4885a110708f3720412f.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/dcd15105d4cc4885a110708f3720412f.jpg" alt="Django--(2)模型(Model)属性与参数整理_第21张图片" width="650" height="207" style="border:1px solid black;"></a></p> <h5>F对象：类属性之间的比较</h5> <p>查询图书阅读量>评论量的图书</p> <pre><code class="prism language-python"><span class="token keyword">from</span> django<span class="token punctuation">.</span>db<span class="token punctuation">.</span>models <span class="token keyword">import</span> F books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>bread__gt<span class="token operator">=</span>F<span class="token punctuation">(</span><span class="token string">'bcomment'</span><span class="token punctuation">)</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/9d9f9038c5b84ed88b903815a3e823f8.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/9d9f9038c5b84ed88b903815a3e823f8.jpg" alt="Django--(2)模型(Model)属性与参数整理_第22张图片" width="650" height="134" style="border:1px solid black;"></a><br> 查询图书阅读量> 2倍评论量的图书</p> <pre><code class="prism language-python"><span class="token keyword">from</span> django<span class="token punctuation">.</span>db<span class="token punctuation">.</span>models <span class="token keyword">import</span> F books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>bread__gt<span class="token operator">=</span>F<span class="token punctuation">(</span><span class="token string">'bcomment'</span><span class="token punctuation">)</span><span class="token operator"></span><span class="token number">2</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/70c42c86b0da4e9286191fbade47a5dd.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/70c42c86b0da4e9286191fbade47a5dd.jpg" alt="Django--(2)模型(Model)属性与参数整理_第23张图片" width="650" height="128" style="border:1px solid black;"></a></p> <h5>Q对象：查询条件之间的逻辑比较</h5> <p><mark>且</mark> <code>&</code><br> 查询 id>3 并且阅读量大于30 的图书信息</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>id__gt<span class="token operator">=</span><span class="token number">3</span><span class="token punctuation">,</span>bread__gt<span class="token operator">=</span><span class="token number">30</span><span class="token punctuation">)</span> </code></pre> <p>等效</p> <pre><code class="prism language-python"><span class="token keyword">from</span> django<span class="token punctuation">.</span>db<span class="token punctuation">.</span>models <span class="token keyword">import</span> Q books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>Q<span class="token punctuation">(</span>id__gt<span class="token operator">=</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token operator">&</span>Q<span class="token punctuation">(</span>bread__gt<span class="token operator">=</span><span class="token number">30</span><span class="token punctuation">)</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/e17bfb17390844e3b2830b151517e265.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/e17bfb17390844e3b2830b151517e265.jpg" alt="Django--(2)模型(Model)属性与参数整理_第24张图片" width="650" height="135" style="border:1px solid black;"></a><br> <a href="http://img.e-com-net.com/image/info8/44badb3dee7349858f8b6876388d03e3.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/44badb3dee7349858f8b6876388d03e3.jpg" alt="Django--(2)模型(Model)属性与参数整理_第25张图片" width="650" height="143" style="border:1px solid black;"></a><br> <mark>或</mark> <code>\|</code><br> 查询 id>3 或者阅读量>30 的图书</p> <pre><code class="prism language-python"><span class="token keyword">from</span> django<span class="token punctuation">.</span>db<span class="token punctuation">.</span>models <span class="token keyword">import</span> Q books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>Q<span class="token punctuation">(</span>id__gt<span class="token operator">=</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token operator">\|</span>Q<span class="token punctuation">(</span>bread__gt<span class="token operator">=</span><span class="token number">30</span><span class="token punctuation">)</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/a5d3945eed0546139c2ff0c5f78f062d.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/a5d3945eed0546139c2ff0c5f78f062d.jpg" alt="Django--(2)模型(Model)属性与参数整理_第26张图片" width="650" height="232" style="border:1px solid black;"></a><br> <mark>非</mark> <code>~</code><br> 查询 id 不等于5 的图书</p> <pre><code class="prism language-python"><span class="token keyword">from</span> django<span class="token punctuation">.</span>db<span class="token punctuation">.</span>models <span class="token keyword">import</span> Q books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span><span class="token operator">~</span>Q<span class="token punctuation">(</span><span class="token builtin">id</span><span class="token operator">=</span><span class="token number">5</span><span class="token punctuation">)</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/a4a8e9f5aad34d2a84d5da92436d5bc7.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/a4a8e9f5aad34d2a84d5da92436d5bc7.jpg" alt="Django--(2)模型(Model)属性与参数整理_第27张图片" width="619" height="254" style="border:1px solid black;"></a></p> <h5>聚合：对查询结果进行聚合操作</h5> <p>使用<code>aggregate()</code>函数来使用聚合，返回是字典</p> <h6><code>sum</code> 求和</h6> <p>查询所有图书阅读量的总和</p> <pre><code class="prism language-python"><span class="token keyword">from</span> django<span class="token punctuation">.</span>db<span class="token punctuation">.</span>models <span class="token keyword">import</span> Sum bread_num <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">all</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span>aggregate<span class="token punctuation">(</span>Sum<span class="token punctuation">(</span><span class="token string">'bread'</span><span class="token punctuation">)</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/cf7c6c428f184f23afac33eec04fa84b.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/cf7c6c428f184f23afac33eec04fa84b.jpg" alt="在这里插入图片描述" width="650" height="89"></a></p> <h6><code>count</code> 统计</h6> <p>查询所有图书的数目</p> <pre><code class="prism language-python"><span class="token keyword">from</span> django<span class="token punctuation">.</span>db<span class="token punctuation">.</span>models <span class="token keyword">import</span> Count books_num <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">all</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span>aggregate<span class="token punctuation">(</span>Count<span class="token punctuation">(</span><span class="token string">'id'</span><span class="token punctuation">)</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/8434b40d64594133afff26948423b77f.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/8434b40d64594133afff26948423b77f.jpg" alt="Django--(2)模型(Model)属性与参数整理_第28张图片" width="650" height="145" style="border:1px solid black;"></a><br> 等效</p> <pre><code class="prism language-python"><span class="token keyword">from</span> django<span class="token punctuation">.</span>db<span class="token punctuation">.</span>models <span class="token keyword">import</span> Count books_num <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span>aggregate<span class="token punctuation">(</span>Count<span class="token punctuation">(</span><span class="token string">'id'</span><span class="token punctuation">)</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/0dfce9238dde424b87dec53a46241053.png" target="_blank"><img src="http://img.e-com-net.com/image/info8/0dfce9238dde424b87dec53a46241053.png" alt="Django--(2)模型(Model)属性与参数整理_第29张图片" width="662" height="113" style="border:1px solid black;"></a><br> <code>count()</code> 函数：统计满足条件的数目，返回的是一个数字<br> 统计所有图书的数目</p> <pre><code class="prism language-python">books_num <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">all</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span>count<span class="token punctuation">(</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/3b458f665a134e829ef525af8c5635dd.png" target="_blank"><img src="http://img.e-com-net.com/image/info8/3b458f665a134e829ef525af8c5635dd.png" alt="在这里插入图片描述" width="594" height="84"></a><br> 统计 id>3 的所有图书的数目</p> <pre><code class="prism language-python">books_num <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>id__gt<span class="token operator">=</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">.</span>count<span class="token punctuation">(</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/7cc13546ef294f189bce4a3a11c6ddfc.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/7cc13546ef294f189bce4a3a11c6ddfc.jpg" alt="在这里插入图片描述" width="650" height="72"></a></p> <h6><code>avg</code> 求平均值</h6> <h6><code>max</code> 求最大值</h6> <h6><code>min</code> 求最小值</h6> <h4>插入、更新、删除</h4> <p>调用一个模型类对象<code>save()</code>方法的时候就可以实现对模型类对应数据表的<mark>插入和更新</mark><br> 调用一个模型类对象<code>delete()</code>方法的时候就可以实现对模型类对应数据表的<mark>删除</mark></p> <h3>模型类关系</h3> <h4>一对多关系</h4> <p>例如：一本图书有多个英雄<br> <code>models.ForeignKey()</code>定义在<mark>多的类中</mark><br> 在 <code>CTTIC/app/models.py</code> 中</p> <pre><code class="prism language-python"><span class="token keyword">from</span> django<span class="token punctuation">.</span>db <span class="token keyword">import</span> models <span class="token comment"># Create your models here.</span> <span class="token comment">#图书类</span> <span class="token keyword">class</span> <span class="token class-name">BookInfo</span><span class="token punctuation">(</span>models<span class="token punctuation">.</span>Model<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token triple-quoted-string string">'''图书模型类'''</span> <span class="token comment">#id 自动生成</span> <span class="token comment">#图书名称</span> btitle <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token comment">#出版日期</span> bpub_date <span class="token operator">=</span> models<span class="token punctuation">.</span>DateField<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment">#阅读量</span> bread <span class="token operator">=</span> models<span class="token punctuation">.</span>IntegerField<span class="token punctuation">(</span>default<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">)</span> <span class="token comment">#评论量</span> bcomment <span class="token operator">=</span> models<span class="token punctuation">.</span>IntegerField<span class="token punctuation">(</span>default<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">)</span> <span class="token comment">#删除标记</span> isDelete <span class="token operator">=</span> models<span class="token punctuation">.</span>BooleanField<span class="token punctuation">(</span>default<span class="token operator">=</span><span class="token boolean">False</span><span class="token punctuation">)</span> <span class="token keyword">def</span> <span class="token function">__str__</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token comment"># 返回书名</span> <span class="token keyword">return</span> self<span class="token punctuation">.</span>btitle <span class="token comment">#英雄人物类</span> <span class="token keyword">class</span> <span class="token class-name">HeroInfo</span><span class="token punctuation">(</span>models<span class="token punctuation">.</span>Model<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token comment">#英雄名 hname</span> hname <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token comment"># 性别 hgender,并指定默认值</span> hgender <span class="token operator">=</span> models<span class="token punctuation">.</span>BooleanField<span class="token punctuation">(</span>default<span class="token operator">=</span><span class="token boolean">False</span><span class="token punctuation">)</span> <span class="token comment"># 备注 hcomment</span> hcomment <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">128</span><span class="token punctuation">)</span> isDelete <span class="token operator">=</span> models<span class="token punctuation">.</span>BooleanField<span class="token punctuation">(</span>default<span class="token operator">=</span><span class="token boolean">False</span><span class="token punctuation">)</span> <span class="token comment">#关系属性，建立图书类和英雄人物类之间的一对多关系</span> hbook <span class="token operator">=</span> models<span class="token punctuation">.</span>ForeignKey<span class="token punctuation">(</span><span class="token string">'BookInfo'</span><span class="token punctuation">)</span> <span class="token keyword">def</span> <span class="token function">__str__</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token keyword">return</span> self<span class="token punctuation">.</span>hname </code></pre> <h5>关联查询(一对多)</h5> <p>使用博客 Django_182_入门指南图书数据表进行练习<br> <a href="http://img.e-com-net.com/image/info8/db5cdeb17b7c461799b43fcf7efe13e6.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/db5cdeb17b7c461799b43fcf7efe13e6.jpg" alt="Django--(2)模型(Model)属性与参数整理_第30张图片" width="650" height="271" style="border:1px solid black;"></a><br> 查询图书信息，要求图书关联的英雄的描述包含‘八’</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>heroinfo__hcomment__contains<span class="token operator">=</span><span class="token string">'八'</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/8253f9a1a7fa4cf9b3b9ee0cc13738f8.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/8253f9a1a7fa4cf9b3b9ee0cc13738f8.jpg" alt="Django--(2)模型(Model)属性与参数整理_第31张图片" width="650" height="116" style="border:1px solid black;"></a><br> 查询图书信息，要求图书中的英雄的 id>3</p> <pre><code class="prism language-python">books <span class="token operator">=</span> BookInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>heroinfo__id__gt<span class="token operator">=</span><span class="token number">3</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/83f2fefc29584fbf8faec9560345b190.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/83f2fefc29584fbf8faec9560345b190.jpg" alt="Django--(2)模型(Model)属性与参数整理_第32张图片" width="650" height="484" style="border:1px solid black;"></a><br> 查询书名为 “天龙八部” 的所有英雄</p> <pre><code class="prism language-python"><span class="token keyword">from</span> app<span class="token punctuation">.</span>models <span class="token keyword">import</span> HeroInfo heros <span class="token operator">=</span> HeroInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span><span class="token builtin">filter</span><span class="token punctuation">(</span>hbook__btitle<span class="token operator">=</span><span class="token string">'天龙八部'</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/de7f12ff7b2f435eb9d7d5b733677359.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/de7f12ff7b2f435eb9d7d5b733677359.jpg" alt="Django--(2)模型(Model)属性与参数整理_第33张图片" width="650" height="229" style="border:1px solid black;"></a><br> <mark>总结</mark>：<br> 通过多类的条件查询一类的数据<br> <code>一类名.objects.filter(多类名小写__多类属性名__条件名)</code><br> 通过一类的条件查询多类的数据<br> <code>多类名.objects.filter(关联属性__一类属性名__条件名)</code></p> <h4>多对多关系</h4> <p>例如：一个老师有多个学生，一个学生有多个老师<br> <code>models.ManyToManyField()</code> 定义在哪个类中都可以</p> <pre><code class="prism language-python"><span class="token comment">#-- coding:utf-8 --</span> <span class="token keyword">from</span> django<span class="token punctuation">.</span>db <span class="token keyword">import</span> models <span class="token comment">#老师信息</span> <span class="token keyword">class</span> <span class="token class-name">TeacherInfo</span><span class="token punctuation">(</span>models<span class="token punctuation">.</span>Model<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token comment">#老师姓名</span> tname <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token comment"># 老师描述</span> tcomment <span class="token operator">=</span> models<span class="token punctuation">.</span>TextField<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment"># 学生信息</span> <span class="token keyword">class</span> <span class="token class-name">StudentInfo</span><span class="token punctuation">(</span>models<span class="token punctuation">.</span>Model<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token comment"># 学生姓名</span> sname <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token comment"># 学生描述</span> scomment <span class="token operator">=</span> models<span class="token punctuation">.</span>TextField<span class="token punctuation">(</span><span class="token punctuation">)</span> teacher <span class="token operator">=</span> models<span class="token punctuation">.</span>ManyToManyField<span class="token punctuation">(</span><span class="token string">'TeacherInfo'</span><span class="token punctuation">)</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/e035eeca00f74570bc16c8d1161b9d1a.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/e035eeca00f74570bc16c8d1161b9d1a.jpg" alt="在这里插入图片描述" width="250" height="83"></a><br> <a href="http://img.e-com-net.com/image/info8/133035c211474bb89aa00487502a36a0.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/133035c211474bb89aa00487502a36a0.jpg" alt="Django--(2)模型(Model)属性与参数整理_第34张图片" width="650" height="102" style="border:1px solid black;"></a></p> <h4>一对一关系</h4> <p>例如：员工基本信息对应员工详细信息<br> <code>models.OneToOneField()</code> 定义在哪个类中都可以</p> <pre><code class="prism language-python"><span class="token comment">#-- coding:utf-8 --</span> <span class="token keyword">from</span> django<span class="token punctuation">.</span>db <span class="token keyword">import</span> models <span class="token comment">#员工基本信息类</span> <span class="token keyword">class</span> <span class="token class-name">EmployeeBasicInfo</span><span class="token punctuation">(</span>models<span class="token punctuation">.</span>Model<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token comment">#姓名</span> name <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token comment">#年龄</span> age <span class="token operator">=</span> models<span class="token punctuation">.</span>IntegerField<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment"># 性别,默认False对应男</span> gender <span class="token operator">=</span> models<span class="token punctuation">.</span>BooleanField<span class="token punctuation">(</span>default<span class="token operator">=</span><span class="token boolean">False</span><span class="token punctuation">)</span> <span class="token keyword">def</span> <span class="token function">__str__</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token keyword">return</span> self<span class="token punctuation">.</span>name <span class="token comment">#员工详细信息类</span> <span class="token keyword">class</span> <span class="token class-name">EmployeeDetailInfo</span><span class="token punctuation">(</span>models<span class="token punctuation">.</span>Model<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token comment">#联系地址</span> addr <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">255</span><span class="token punctuation">)</span> <span class="token comment">#教育经历</span> education <span class="token operator">=</span> models<span class="token punctuation">.</span>TextField<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment">#关系属性，代表一对一关系</span> employee_basic <span class="token operator">=</span> models<span class="token punctuation">.</span>OneToOneField<span class="token punctuation">(</span><span class="token string">'EmployeeBasicInfo'</span><span class="token punctuation">)</span> <span class="token keyword">def</span> <span class="token function">__str__</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token keyword">return</span> self<span class="token punctuation">.</span>addr </code></pre> <h4>自关联</h4> <p>自关联是一种特殊的一对多的关系,使用<code>models.ForeignKey()</code>关联<br> <a href="http://img.e-com-net.com/image/info8/487e7ffce7e44b2c9b2496bcc6cccb7b.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/487e7ffce7e44b2c9b2496bcc6cccb7b.jpg" alt="Django--(2)模型(Model)属性与参数整理_第35张图片" width="553" height="392" style="border:1px solid black;"></a><br> <code>aParent_id</code> 表示该地区上级所属的id号，若该地区为父级，则为NULL(为空)</p> <pre><code class="prism language-python"><span class="token comment">#-- coding:utf-8 --</span> <span class="token keyword">from</span> django<span class="token punctuation">.</span>db <span class="token keyword">import</span> models <span class="token keyword">class</span> <span class="token class-name">AreaInfo</span><span class="token punctuation">(</span>models<span class="token punctuation">.</span>Model<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token triple-quoted-string string">'''地区模型类'''</span> <span class="token comment"># 地区名称</span> atitle <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token comment"># 关系属性：代表当前地区的父级地区对应id,允许为空</span> aParent <span class="token operator">=</span> models<span class="token punctuation">.</span>ForeignKey<span class="token punctuation">(</span><span class="token string">'self'</span><span class="token punctuation">,</span>null<span class="token operator">=</span><span class="token boolean">True</span><span class="token punctuation">,</span>blank<span class="token operator">=</span><span class="token boolean">True</span><span class="token punctuation">)</span> </code></pre> <p>执行迁移文件生成表</p> <pre><code class="prism language-python">python manage<span class="token punctuation">.</span>py makemigrations python manage<span class="token punctuation">.</span>py migrate </code></pre> <p><a href="http://img.e-com-net.com/image/info8/30b1ede609344c4e9fa8db3d7e5ea3ed.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/30b1ede609344c4e9fa8db3d7e5ea3ed.jpg" alt="在这里插入图片描述" width="316" height="78"></a><br> 插入测试数据</p> <pre><code class="prism language-sql"><span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> app_areainfo <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'110000'</span><span class="token punctuation">,</span> <span class="token string">'北京市'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> app_areainfo <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'110100'</span><span class="token punctuation">,</span> <span class="token string">'北京市'</span><span class="token punctuation">,</span> <span class="token string">'110000'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> app_areainfo <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'110101'</span><span class="token punctuation">,</span> <span class="token string">'东城区'</span><span class="token punctuation">,</span> <span class="token string">'110100'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> app_areainfo <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'110102'</span><span class="token punctuation">,</span> <span class="token string">'西城区'</span><span class="token punctuation">,</span> <span class="token string">'110100'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> app_areainfo <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'110103'</span><span class="token punctuation">,</span> <span class="token string">'朝阳区'</span><span class="token punctuation">,</span> <span class="token string">'110100'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> app_areainfo <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'110104'</span><span class="token punctuation">,</span> <span class="token string">'丰台区'</span><span class="token punctuation">,</span> <span class="token string">'110100'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> app_areainfo <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'110105'</span><span class="token punctuation">,</span> <span class="token string">'石景山区'</span><span class="token punctuation">,</span> <span class="token string">'110100'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> app_areainfo <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'110106'</span><span class="token punctuation">,</span> <span class="token string">'海淀区'</span><span class="token punctuation">,</span> <span class="token string">'110100'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> app_areainfo <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'110107'</span><span class="token punctuation">,</span> <span class="token string">'门头沟区'</span><span class="token punctuation">,</span> <span class="token string">'110100'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> </code></pre> <p>此处数据链接<br> 链接：https://pan.baidu.com/s/1EPQ-ztSaB7n5KFGTk98phw<br> 提取码：drye<br> 复制这段内容后打开百度网盘手机App，操作更方便哦<br> <a href="http://img.e-com-net.com/image/info8/b58a1c11630d4143a94f8d92738d6606.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/b58a1c11630d4143a94f8d92738d6606.jpg" alt="Django--(2)模型(Model)属性与参数整理_第36张图片" width="363" height="630" style="border:1px solid black;"></a><br> 显示广东的上级地区及下级地区<br> 在 <code>CTTIC/app/views.py</code> 中添加视图函数</p> <pre><code class="prism language-python"><span class="token comment">#-- coding:utf-8 --</span> <span class="token keyword">from</span> django<span class="token punctuation">.</span>shortcuts <span class="token keyword">import</span> render <span class="token keyword">from</span> app<span class="token punctuation">.</span>models <span class="token keyword">import</span> AreaInfo <span class="token keyword">def</span> <span class="token function">areas</span><span class="token punctuation">(</span>request<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token triple-quoted-string string">'''获取广州市的上级及下级地区'''</span> <span class="token comment"># 获取广州市的信息</span> area <span class="token operator">=</span> AreaInfo<span class="token punctuation">.</span>objects<span class="token punctuation">.</span>get<span class="token punctuation">(</span>atitle<span class="token operator">=</span><span class="token string">'广州市'</span><span class="token punctuation">)</span> <span class="token comment"># 查询广州市的上级地区</span> parent <span class="token operator">=</span> area<span class="token punctuation">.</span>aParent <span class="token comment"># 查询广州市的下级地区</span> children <span class="token operator">=</span> area<span class="token punctuation">.</span>areainfo_set<span class="token punctuation">.</span><span class="token builtin">all</span><span class="token punctuation">(</span><span class="token punctuation">)</span> context <span class="token operator">=</span> <span class="token punctuation">{</span> <span class="token string">'area'</span><span class="token punctuation">:</span>area<span class="token punctuation">,</span> <span class="token string">'parent'</span><span class="token punctuation">:</span>parent<span class="token punctuation">,</span> <span class="token string">'children'</span><span class="token punctuation">:</span>children<span class="token punctuation">,</span> <span class="token punctuation">}</span> <span class="token keyword">return</span> render<span class="token punctuation">(</span>request<span class="token punctuation">,</span><span class="token string">'app/areas.html'</span><span class="token punctuation">,</span>context<span class="token punctuation">)</span> </code></pre> <p>新建 <code>CTTIC/templates/app/areas.html</code></p> <pre><code class="prism language-html"><span class="token doctype"><!DOCTYPE html></span> <span class="token tag"><span class="token tag"><span class="token punctuation"><</span>html</span> <span class="token attr-name">lang</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>en<span class="token punctuation">"</span></span><span class="token punctuation">></span></span> <span class="token tag"><span class="token tag"><span class="token punctuation"><</span>head</span><span class="token punctuation">></span></span> <span class="token tag"><span class="token tag"><span class="token punctuation"><</span>meta</span> <span class="token attr-name">charset</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>UTF-8<span class="token punctuation">"</span></span><span class="token punctuation">></span></span> <span class="token tag"><span class="token tag"><span class="token punctuation"><</span>title</span><span class="token punctuation">></span></span>自关联案例<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>title</span><span class="token punctuation">></span></span> <span class="token tag"><span class="token tag"><span class="token punctuation"></</span>head</span><span class="token punctuation">></span></span> <span class="token tag"><span class="token tag"><span class="token punctuation"><</span>body</span><span class="token punctuation">></span></span> <span class="token tag"><span class="token tag"><span class="token punctuation"><</span>h1</span><span class="token punctuation">></span></span>当前地区<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>h1</span><span class="token punctuation">></span></span> {{ area.atitle }} <span class="token tag"><span class="token tag"><span class="token punctuation"><</span>br</span><span class="token punctuation">/></span></span> <span class="token tag"><span class="token tag"><span class="token punctuation"><</span>h1</span><span class="token punctuation">></span></span>父级地区<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>h1</span><span class="token punctuation">></span></span> {{ parent.atitle }} <span class="token tag"><span class="token tag"><span class="token punctuation"><</span>br</span><span class="token punctuation">/></span></span> <span class="token tag"><span class="token tag"><span class="token punctuation"><</span>h1</span><span class="token punctuation">></span></span>下级地区<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>h1</span><span class="token punctuation">></span></span> <span class="token tag"><span class="token tag"><span class="token punctuation"><</span>ul</span><span class="token punctuation">></span></span> {% for child in children %} <span class="token tag"><span class="token tag"><span class="token punctuation"><</span>li</span><span class="token punctuation">></span></span>{{ child.atitle }}<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>li</span><span class="token punctuation">></span></span> {% endfor %} <span class="token tag"><span class="token tag"><span class="token punctuation"></</span>ul</span><span class="token punctuation">></span></span> <span class="token tag"><span class="token tag"><span class="token punctuation"></</span>body</span><span class="token punctuation">></span></span> <span class="token tag"><span class="token tag"><span class="token punctuation"></</span>html</span><span class="token punctuation">></span></span> </code></pre> <p><code>CTTIC/app/urls.py</code> 配置路由</p> <pre><code class="prism language-python"><span class="token comment">#-- coding:utf-8 --</span> <span class="token keyword">from</span> django<span class="token punctuation">.</span>conf<span class="token punctuation">.</span>urls <span class="token keyword">import</span> url <span class="token keyword">from</span> app <span class="token keyword">import</span> views urlpatterns <span class="token operator">=</span> <span class="token punctuation">[</span> <span class="token comment"># 通过url函数设置url配置项</span> url<span class="token punctuation">(</span>r<span class="token string">'^areas$'</span><span class="token punctuation">,</span>views<span class="token punctuation">.</span>areas<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">]</span> </code></pre> <p><a href="http://img.e-com-net.com/image/info8/097d8971b55e497dae5b8ccc39207be4.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/097d8971b55e497dae5b8ccc39207be4.jpg" alt="Django--(2)模型(Model)属性与参数整理_第37张图片" width="445" height="886" style="border:1px solid black;"></a></p> <h2>面向对象 ORM</h2> <p>Django模型层 ORM 的一个强大之处是对模型继承的支持，该技术将Python面向对象的编程方法与数据库面向关系表的数据结构有机结合<br> Django支持三种风格的模型继承</p> <ol> <li>抽象类继承：<br> 通过 Meta 中定义属性 <code>abstract = True</code><br> 父类继承 <code>models.Model</code>，但不会在底层数据库中生成相应的数据表<br> 父类的属性列存储在子类的数据表中<br> 将某些字段定义在抽象基类中，<mark>免于重复定义这些字段</mark></li> <li>多表继承：<br> 多表继承的每个模型类都在底层数据库中生成相应的数据表管理数据<br> 在多表继承技术中，无论是父表还是子表都会用数据库中相应的数据表维护模型数据，父类中的字段不会重复第在多个子类的相关数据表中进行定义<br> <mark>从某种意义上讲，多表继承才是真正面向对象的ORM技术</mark><br> 多表继承不需要特殊的关键字<br> 在Django内部通过在父类模型和子模型之间建立一对一关系来实现多表继承技术</li> <li>代理模型继承：<br> 通过在子类 Meta 中定义 <code>proxy=True</code> 来实现<br> 父类用于在底层数据库中管理数据表<br> 而子类不定义数据列，只定义查询数据集的排序方式等元数据<br> 子类只用于管理父类的数据，而不实际存储数据<br> 使用原因：<br> 是子类中新的特性不会影响父类模型及其已有代码的行为</li> </ol> <h3>抽象类继承</h3> <pre><code class="prism language-python"><span class="token comment"># -- coding: utf-8 --</span> <span class="token keyword">from</span> __future__ <span class="token keyword">import</span> unicode_literals <span class="token keyword">from</span> django<span class="token punctuation">.</span>db <span class="token keyword">import</span> models <span class="token comment"># Create your models here.</span> <span class="token comment">#父类</span> <span class="token keyword">class</span> <span class="token class-name">MessageBase</span><span class="token punctuation">(</span>models<span class="token punctuation">.</span>Model<span class="token punctuation">)</span><span class="token punctuation">:</span> content <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">100</span><span class="token punctuation">,</span>null<span class="token operator">=</span><span class="token boolean">True</span><span class="token punctuation">)</span> user_name <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">80</span><span class="token punctuation">,</span>null<span class="token operator">=</span><span class="token boolean">True</span><span class="token punctuation">)</span> pub_date <span class="token operator">=</span> models<span class="token punctuation">.</span>DateField<span class="token punctuation">(</span>null<span class="token operator">=</span><span class="token boolean">True</span><span class="token punctuation">)</span> <span class="token keyword">class</span> <span class="token class-name">Meta</span><span class="token punctuation">:</span> abstract <span class="token operator">=</span> <span class="token boolean">True</span> <span class="token comment">#定义本类为抽象基类 </span> <span class="token comment"># 子类</span> <span class="token keyword">class</span> <span class="token class-name">Moment</span><span class="token punctuation">(</span>MessageBase<span class="token punctuation">)</span><span class="token punctuation">:</span> headline <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">50</span><span class="token punctuation">)</span> LEVELS <span class="token operator">=</span> <span class="token punctuation">(</span> <span class="token punctuation">(</span><span class="token string">'1'</span><span class="token punctuation">,</span><span class="token string">'Very good'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">'2'</span><span class="token punctuation">,</span><span class="token string">'Good'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">'3'</span><span class="token punctuation">,</span><span class="token string">'Normal'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">'4'</span><span class="token punctuation">,</span><span class="token string">'Bad'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">)</span> <span class="token comment"># 子类</span> <span class="token keyword">class</span> <span class="token class-name">Comment</span><span class="token punctuation">(</span>MessageBase<span class="token punctuation">)</span><span class="token punctuation">:</span> level <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">1</span><span class="token punctuation">,</span>choices <span class="token operator">=</span> LEVELS<span class="token punctuation">)</span> </code></pre> <p>3个类映射到数据库后，会被定义为两个数据表</p> <p>数据表 moment: 有 id,content,user_name,pub_date,headline 等5个字段<br> 数据表 comment: 有 id,content,user_name,pub_date,level 等5个字段<br> <a href="http://img.e-com-net.com/image/info8/ae82445d926347f4a529019d8227723c.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/ae82445d926347f4a529019d8227723c.jpg" alt="Django--(2)模型(Model)属性与参数整理_第38张图片" width="650" height="209" style="border:1px solid black;"></a></p> <h3>多表继承</h3> <pre><code class="prism language-python"><span class="token comment"># -- coding: utf-8 --</span> <span class="token keyword">from</span> __future__ <span class="token keyword">import</span> unicode_literals <span class="token keyword">from</span> django<span class="token punctuation">.</span>db <span class="token keyword">import</span> models <span class="token comment"># Create your models here.</span> <span class="token keyword">class</span> <span class="token class-name">MessageBase</span><span class="token punctuation">(</span>models<span class="token punctuation">.</span>Model<span class="token punctuation">)</span><span class="token punctuation">:</span> content <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">100</span><span class="token punctuation">,</span>null<span class="token operator">=</span><span class="token boolean">True</span><span class="token punctuation">)</span> user_name <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">80</span><span class="token punctuation">,</span>null<span class="token operator">=</span><span class="token boolean">True</span><span class="token punctuation">)</span> pub_date <span class="token operator">=</span> models<span class="token punctuation">.</span>DateField<span class="token punctuation">(</span>null<span class="token operator">=</span><span class="token boolean">True</span><span class="token punctuation">)</span> <span class="token keyword">class</span> <span class="token class-name">Moment</span><span class="token punctuation">(</span>MessageBase<span class="token punctuation">)</span><span class="token punctuation">:</span> headline <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">50</span><span class="token punctuation">)</span> <span class="token keyword">class</span> <span class="token class-name">Comment</span><span class="token punctuation">(</span>MessageBase<span class="token punctuation">)</span><span class="token punctuation">:</span> level <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">1</span><span class="token punctuation">,</span>choices<span class="token operator">=</span>LEVELS<span class="token punctuation">)</span> </code></pre> <p>生成3个数据表<br> 数据表 MessageBase: 有 id,content,user_name,pub_date 等4个字段<br> 数据表 Moment: 有id，headline等两个字段<br> 数据表 Comment: 有 id,level 等两个字段</p> <h3>代理类继承</h3> <pre><code class="prism language-python"><span class="token comment"># -- coding: utf-8 --</span> <span class="token keyword">from</span> __future__ <span class="token keyword">import</span> unicode_literals <span class="token keyword">from</span> django<span class="token punctuation">.</span>db <span class="token keyword">import</span> models <span class="token comment"># Create your models here.</span> <span class="token keyword">class</span> <span class="token class-name">Moment</span><span class="token punctuation">(</span>models<span class="token punctuation">.</span>Model<span class="token punctuation">)</span><span class="token punctuation">:</span> content <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">100</span><span class="token punctuation">,</span>null<span class="token operator">=</span><span class="token boolean">True</span><span class="token punctuation">)</span> user_name <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">80</span><span class="token punctuation">,</span>null<span class="token operator">=</span><span class="token boolean">True</span><span class="token punctuation">)</span> pub_date <span class="token operator">=</span> models<span class="token punctuation">.</span>DateField<span class="token punctuation">(</span>null<span class="token operator">=</span><span class="token boolean">True</span><span class="token punctuation">)</span> headline <span class="token operator">=</span> models<span class="token punctuation">.</span>CharField<span class="token punctuation">(</span>max_length<span class="token operator">=</span><span class="token number">50</span><span class="token punctuation">)</span> <span class="token keyword">class</span> <span class="token class-name">OrderedMoment</span><span class="token punctuation">(</span>Moment<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token keyword">class</span> <span class="token class-name">Meta</span><span class="token punctuation">:</span> proxy <span class="token operator">=</span> <span class="token boolean">True</span><span class="token punctuation">;</span> ordering <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token string">"-pub_date"</span><span class="token punctuation">]</span> </code></pre> </div> </div> </div> </div> </div> <!--PC和WAP自适应版--> <div id="SOHUCS" sid="1727301095409135616"></div> <script type="text/javascript" src="/views/front/js/chanyan.js"></script> <!-- 文章页-底部动态广告位 --> <div class="youdao-fixed-ad" id="detail_ad_bottom"></div> </div> <div class="col-md-3"> <div class="row" id="ad"> <!-- 文章页-右侧1 动态广告位 --> <div id="right-1" class="col-lg-12 col-md-12 col-sm-4 col-xs-4 ad"> <div class="youdao-fixed-ad" id="detail_ad_1"> </div> </div> <!-- 文章页-右侧2 动态广告位 --> <div id="right-2" class="col-lg-12 col-md-12 col-sm-4 col-xs-4 ad"> <div class="youdao-fixed-ad" id="detail_ad_2"></div> </div> <!-- 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