基于连接属性的区分符 [英] Discriminator based on joined property

问题描述

假设我有这种关系:

abstract class Base { int Id; int JoinedId; ... }
class Joined { int Id; int Discriminator; ... }
class Sub1 : Base { ... }
class Sub2 : Base { ... }

对于以下表格:

table Base ( Id int, JoinedId int, ... )
table Joined ( Id int, Discriminator int, ... )

我想为Base，Sub1，Sub2关系建立一个按层次结构的表继承映射，但要使用Joined类中的Disciminator属性作为鉴别符.

I would like to set up a table-per-hierarchy inheritance mapping for the Base, Sub1, Sub2 relationships, but using the Disciminator property from the Joined class as the discriminator.

以下是映射文件的基本概念:

Here's the general idea for the mapping file:

<class name="Base" table="Base">
    <id name="Id"><generator class="identity"/></id>

    <discriminator /> <!-- ??? or <join> or <many-to-one>? -->

    <subclass name="Sub1" discriminator-value="1">...</subclass>
    <subclass name="Sub2" discriminator-value="2">...</subclass>
</class>

是否可以用<discriminator>，<join>或<many-to-one>完成类似的操作? NHiberante似乎假设鉴别符是给定表上的一列(这对我来说很有意义.我知道这是非正统的).

Is there any way of accomplishing something like this with the <discriminator>, <join>, or <many-to-one>? NHiberante seems to assume the discriminator is a column on the given table (which makes sense to me.. I know this is unorthodox).

谢谢.

推荐答案

不能在Joined上使用带有子选择项的判别式吗?

Can't you use a discriminator-formula with a subselect on Joined?

<discriminator formula="(select j.discriminator from Joined j where j.id = joinedid)">

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