Java / JPA |使用指定的继承类型进行查询 [英] Java /JPA | Query with specified inherited type

问题描述

我正在构建一个通用表Sample的查询，我有几种类型继承自这个表SampleOne，SampleTwo。
我需要一个类似的查询：

I am building a query on a generic table "Sample" and I have several types which inherit from this table "SampleOne", "SampleTwo". I require a query like :

select s from Sample where s.type = :type

其中type将是表的鉴别值。是否有可能（并避免创建特定于实体的查询，每个SampleOne，SampleTwo等等）

where type would be a discriminator value of the table. Is it possible in any way ( and avoid to create an entity specific queries, one for each SampleOne, SampleTwo... etc )

我将非常感谢此处的任何输入话题，

I would greatly appreciate any input in this topic,

亲切的问候，
P。

Kind regards, P.

推荐答案

在JPA 2.0中，您可以使用 TYPE 表达式（尽管目前它不适用于Hibernate中的参数，请参阅 HHH-5282 ）：

In JPA 2.0 you can use TYPE expression (though currently it doesn't work with parameters in Hibernate, see HHH-5282):

select s from Sample s where TYPE(s) = :type

类似Hibernate的特定表达式是 .class ：

The similar Hibernate-specific expression is .class:

select s from Sample s where s.class = :type

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