CODEWITHSUNDEEP
javahibernatejpa
fujy
fujy

Reputation: 5274

Hibernate / JPA: Is it possible to Override @Id field?

Is there a method to reassign the @Id in child entity after it was assigned to some field in the parent entity

For example:

@MappedSuperclass
@Access(AccessType.FIELD)
public abstract class Parent implements Serializable {

  @Id
  protected Integer parentId;

  public Integer getId() {
    return parentId;
  }

  public void setId(Integer id) {
    this.id = parentId;
  }
}


@Entity
@Access(AccessType.FIELD)
public class Child extends Parent implements Serializable {

  /*
   What should be added to this entity to re assign the @Id to a new field and 
   make the parentId field just an ordianry field in the Child, not the entity Id
  */
  @Id
  private Long childId;

}

I have tried to use @AttributeOverride, but all it could provide is to rename the id column name.

Upvotes: 4

Views: 6478

Answers (2)

ben75
ben75

Reputation: 28746

It sounds like a design problem.

The proper way to achieve this is probably to define another class : @MappedSuperclass GenericEntity with all attributes of Parent except the parentId :

@MappedSuperclass
@Access(AccessType.FIELD)
public abstract class GenericEntity implements Serializable {
     ... all your common attributes without parentId
}

@MappedSuperclass
public abstract class Parent extends GenericEntity implements Serializable {

    @Id
    protected Integer parentId;

    public Integer getId() {
        return parentId;
    }

    public void setId(Integer id) {
        this.id = parentId;
    }

    //nothing more in this class
}

@Entity
public class Child extends GenericEntity implements Serializable {

   @Id
   private Long childId;

   private Integer parentId; //if you need it

   ...
}

An alternative experimental solution can be to hide the parentId field in the Child class.

Disclaimer : I don't recommend this approach, and I'm not sure it will work !

@Entity
@Access(AccessType.FIELD)
public class Child extends GenericEntity implements Serializable {

   @Id
   private Long childId;

   private Integer parentId;

   ...
}

Upvotes: 4

Korgen
Korgen

Reputation: 5409

you can override annotation metadata by xml: for hibernate see e.g. this post

for general JPA see e.g. this post

Upvotes: 0

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