休眠< set>从加入表中输入密钥 [英] Hibernate <set> key from joined table

问题描述

我想知道是否可以在Hibernate映射中以这种方式定义 Set ，那么该元素将在原始中指定不是列（ FOO ）表格，但加入了一个（ BAR ）。假设我们有一些 FooContainer.hbm.xml ，其中包含 Foo code> objects：



I wonder if it's possible to define Set in Hibernate mapping in a such way, that element would specify not column in original (FOO) table, but in joined one (BAR). Let's say we have some FooContainer.hbm.xml, which contains Set of Foo objects:

<set ...>
  <key column="COLUMN_FROM_BAR" />
  <one-to-many class="xyz.Foo" />
</set>

这里 FOO 的FK为 BAR （ FOO.BAR_ID ），因此通过Foo.hbm.xml中的元素完成连接：

Here FOO has FK to BAR (FOO.BAR_ID), so joining is done through element in Foo.hbm.xml:

<many-to-one class="xyz.Bar" fetch="join" column="BAR_ID" foreign-key="barId" ... />

导致加入 FOO-BAR 时，只要 xyz.Foo 被提取。

which results in joined FOO-BAR select whenever xyz.Foo is fetched.

问题是生成的 Set fetching select的条件如下所示：

Problem is that where condition of generated Set fetching select is something like:

... WHERE _FOO_0.COLUMN_FROM_BAR = ?

当需要时：

when desired one is:

... WHERE _BAR_0.COLUMN_FROM_BAR = ?

推荐答案

在 Java持久化与Hibernate （第295页）。诀窍从目标类（ Foo ）设置不同的设置表（ BAR ）：

Found the answer in Java Persistence with Hibernate (page 296). Trick is setting different set table (BAR) from target class (Foo):

  <set table="BAR" ...>
    <key column="COLUMN_FROM_BAR" /> 
    <many-to-many
      class="xyz.Foo"
      column="BAR_ID"
      unique="true"
      />
  </set>

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