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javajpahibernate-mapping

How to make JPA interpret List<Element> (size only 0 or 1) as single Element

class Entity {
    private InnnerEntity innerEntity;
}

I had above structure in JPA previously, but now I have to change it to collection like:

class Entity {
    private List<InnnerEntity> innerEntity;
}

And this list will contain only 1 or 0 elements. So I need to make JPA work with that structure exactly as it was before. I mean to still have mapping one to one or in other case have it as an embedded entity. Is that even possible ?

Solution

  • You can use Bean validation to limit the size of the collection to 1 but you will have to use OneToMany because OneToOne doesn't work on collections:

    class Entity {

    @Size(1)
    @OneToMany
    private List<InnnerEntity> innerEntity;

}