JPA map collection of Enums

Gennady_Shumakher_42512 0
Viewed 86663

Is there a way in JPA to map a collection of Enums within the Entity class? Or the only solution is to wrap Enum with another domain class and use it to map the collection?

@Entity
public class Person {
    public enum InterestsEnum {Books, Sport, etc...  }
    //@???
    Collection<InterestsEnum> interests;
}

I am using Hibernate JPA implementation, but of course would prefer implementation agnostic solution.

jakarta-ee jpa java
6 Answers

using Hibernate you can do

@ElementCollection(targetElement = InterestsEnum.class)
@JoinTable(name = "tblInterests", joinColumns = @JoinColumn(name = "personID"))
@Column(name = "interest", nullable = false)
@Enumerated(EnumType.STRING)
Collection<InterestsEnum> interests;
Admin1

tl;dr A short solution would be the following:

@ElementCollection(targetClass = InterestsEnum.class)
@CollectionTable
@Enumerated(EnumType.STRING)
Collection<InterestsEnum> interests;

The long answer is that with this annotations JPA will create one table that will hold the list of InterestsEnum pointing to the main class identifier (Person.class in this case).

@ElementCollections specify where JPA can find information about the Enum

@CollectionTable create the table that hold relationship from Person to InterestsEnum

@Enumerated(EnumType.STRING) tell JPA to persist the Enum as String, could be EnumType.ORDINAL

user_27666870

Collections in JPA refer to one-to-many or many-to-many relationships and they can only contain other entities. Sorry, but you'd need to wrap those enums in an entity. If you think about it, you'd need some sort of ID field and foreign key to store this information anyway. That is unless you do something crazy like store a comma-separated list in a String (don't do this!).

cletus_183930
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