Entityframework code first出现错误：列名 Discriminator 无效

分手后的思念是犯贱 2022-05-29 00:47 175阅读 0赞

前几天使用code first碰到错误：列名 'Discriminator' 无效。这是一个很少见的错误，搜索了很久才发现是code first的poco实体对象的继承问题。

比如，我定义了一个实体类，对应数据库的Project表：

<table> 
 <tbody style="background:none;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;"> 
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    <div style="height:14px;margin:0px;padding:0px .5em 0px 1em;background:none;border:0px;float:none;line-height:1.1em;text-align:right;vertical-align:baseline;width:auto;min-height:auto;white-space:pre;">
      1 
    </div> 
    <div style="height:14px;margin:0px;padding:0px .5em 0px 1em;background:none;border:0px;float:none;line-height:1.1em;text-align:right;vertical-align:baseline;width:auto;min-height:auto;white-space:pre;">
      2 
    </div> 
    <div style="height:14px;margin:0px;padding:0px .5em 0px 1em;background:none;border:0px;float:none;line-height:1.1em;text-align:right;vertical-align:baseline;width:auto;min-height:auto;white-space:pre;">
      3 
    </div> 
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      4 
    </div> 
    <div style="height:14px;margin:0px;padding:0px .5em 0px 1em;background:none;border:0px;float:none;line-height:1.1em;text-align:right;vertical-align:baseline;width:auto;min-height:auto;white-space:pre;">
      5 
    </div> 
    <div style="height:14px;margin:0px;padding:0px .5em 0px 1em;background:none;border:0px;float:none;line-height:1.1em;text-align:right;vertical-align:baseline;width:auto;min-height:auto;white-space:pre;">
      6 
    </div></td> 
   <td style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;width:615px;background:none;border-width:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;min-height:auto;font-size:13px;"> 
    <div style="margin:0px;padding:0px;background:none;border:0px;float:none;line-height:1.1em;vertical-align:baseline;width:auto;min-height:auto;"> 
     <div style="height:14px;margin:0px;padding:0px 1em;background:none;border:0px;float:none;line-height:1.1em;vertical-align:baseline;width:auto;min-height:auto;"> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;color:#000000;">[Table(</code> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;color:#0000FF;">"T_Student"</code> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;color:#000000;">)]</code> 
     </div> 
     <div style="height:14px;margin:0px;padding:0px 1em;background:none;border:0px;float:none;line-height:1.1em;vertical-align:baseline;width:auto;min-height:auto;"> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;font-weight:bold;min-height:auto;font-size:13px;color:rgb(255,120,0);">public</code>&nbsp; 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;font-weight:bold;min-height:auto;font-size:13px;color:rgb(255,120,0);">class</code>&nbsp; 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;color:#000000;">Student</code> 
     </div> 
     <div style="height:14px;margin:0px;padding:0px 1em;background:none;border:0px;float:none;line-height:1.1em;vertical-align:baseline;width:auto;min-height:auto;"> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;color:#000000;">{ </code> 
     </div> 
     <div style="height:14px;margin:0px;padding:0px 1em;background:none;border:0px;float:none;line-height:1.1em;vertical-align:baseline;width:auto;min-height:auto;"> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;">&nbsp;&nbsp;&nbsp;&nbsp;</code> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;font-weight:bold;min-height:auto;font-size:13px;color:rgb(255,120,0);">public</code>&nbsp; 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;font-weight:bold;min-height:auto;font-size:13px;color:rgb(255,120,0);">int</code>&nbsp; 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;color:#000000;">Id&nbsp;{&nbsp;</code> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;font-weight:bold;min-height:auto;font-size:13px;color:rgb(255,120,0);">get</code> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;color:#000000;">;&nbsp;</code> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;font-weight:bold;min-height:auto;font-size:13px;color:rgb(255,120,0);">set</code> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;color:#000000;">;&nbsp;}</code> 
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      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;font-weight:bold;min-height:auto;font-size:13px;color:rgb(255,120,0);">public</code>&nbsp; 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;font-weight:bold;min-height:auto;font-size:13px;color:rgb(255,120,0);">string</code>&nbsp; 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;color:#000000;">Name&nbsp;{&nbsp;</code> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;font-weight:bold;min-height:auto;font-size:13px;color:rgb(255,120,0);">get</code> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;color:#000000;">;&nbsp;</code> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;font-weight:bold;min-height:auto;font-size:13px;color:rgb(255,120,0);">set</code> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;color:#000000;">;&nbsp;}</code> 
     </div> 
     <div style="height:14px;margin:0px;padding:0px 1em;background:none;border:0px;float:none;line-height:1.1em;vertical-align:baseline;width:auto;min-height:auto;"> 
      <code style="font-family:Monaco, Menlo, Consolas, 'Courier New', monospace;background:none;border:0px;float:none;line-height:1.1em;margin:0px;padding:0px;vertical-align:baseline;width:auto;min-height:auto;font-size:13px;color:#000000;">}</code> 
     </div> 
    </div></td> 
  </tr> 
 </tbody> 
</table>

后来又定义了一个子类ChildProject继承于它，但是子类不对应数据库任何表：

于是每次EF的Context访问到Project或者ChildProject的时候，都出现了错误：列名 'Discriminator' 无效。

解决办法：子类并不映射到任何数据库，加上一个不映射的属性\[NotMapped\]就可以了。

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