java Hibernate 鉴别器列，每个子类都有表
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Hibernate discriminator column with table per subclass
提问by Ransom Briggs
Right now I am using a table per subclass approach to model my data. A simplification of my hierarchy is:
现在我正在使用每个子类的表来为我的数据建模。我的层次结构的简化是：
abstract class Abstract {
/* common data stored in abstract */
}
class ConcreteTypeA1 extends Abstract {
/* extra data stored in concrete_type_a_1 */
}
class ConcreteTypeA2 extends Abstract {
/* extra data stored in concrete_type_a_2 */
}
class ConcreteTypeB extends Abstract {
/* extra data stored in concrete_type_b */
}
So it does three outer joins where I grab instances of type Abstract (in reality it is twelve). What I realized yesterday is that ConcreteTypeA1 and ConcreteTypeA2 really have the same extra data, they just behave differently, so what I would like to do is reduce the number of joins by stuffing these two classes into one table and using a discriminator column. How / can I accomplish this?
所以它执行三个外部连接，我在其中获取 Abstract 类型的实例（实际上是十二个）。昨天我意识到 ConcreteTypeA1 和 ConcreteTypeA2 确实具有相同的额外数据，只是它们的行为不同，所以我想做的是通过将这两个类填充到一个表中并使用鉴别器列来减少连接的数量。我如何/我能做到这一点？
class Abstract {
/* common data stored in abstract */
}
abstract class ConcreteTypeA extends Abstract {
/* extra data stored in abstract_type_a */
}
class ConcreteTypeA1 extends ConcreteTypeA {
/* just behavior, no extra data, uses data in abstract_type_a */
}
class ConcreteTypeA2 extends ConcreteTypeA {
/* just behavior, no extra data, uses data in abstract_type_a */
}
class ConcreteTypeB extends Abstract {
/* extra data stored in concrete_type_b */
}
采纳答案by Ransom Briggs
Used answer from this question as per Vincents' advice.
根据文森特的建议使用了这个问题的答案。
How to mix inheritance strategies with JPA annotations and Hibernate?
回答by Manoj
use this on Parent class
在父类上使用它
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(
name="type",
discriminatorType=DiscriminatorType.STRING)
and on concrete classes use
并在具体类上使用
@DiscriminatorValue("TypeA")
