MappingPurpose

This annotation is useful to indicate an unused field in a class declared as Entity. Its purpose is to indicate that the field is used for mapping, in order to create a table or a relationship in the database

Usage

JavaKotlin

@Entity
public class SimpleEntity {

    @Id
    private final String name;

    // unused field in the class
    @OneToOne
    @MappingPurpose // annotate it
    @JoinColumn(name = "item_id")
    private RelationshipItem item;

    public SimpleEntity(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

}

import jakarta.persistence.Entity
import jakarta.persistence.Id
import jakarta.persistence.OneToOne
import jakarta.persistence.JoinColumn

@Entity
class SimpleEntity(
    @Id
    val name: String
) {

    // unused field in the class
    @OneToOne
    @MappingPurpose // annotate it
    @JoinColumn(name = "item_id")
    var item: RelationshipItem? = null

}