Hibernate: Multiple tables, same object

Question

I am trying to write a simple app that contains one table that keeps track of payments each user has made and a second table that contains total amount each user has paid (sum of all payments). Currently, both tables have the same fields (firstName, lastName, amount) and I have mapped them from the same Java class and I have trouble mapping that class to multiple tables. Is there any simple solution to this?

@Entity
@Table(name="Payment")
public class Payment{

  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  private Long id;

  @Column
  @NotNull
  private String firstNname;

  @Column
  @NotNull
  private String lastNname;

  @Column
  @NotNull
  private double amount;

... Constructor, getters and setters
}

Could you please show code that you have tried and problematic place. — SternK
– SternK, Commented Sep 12, 2020 at 11:03
Honestly, there is very little code, because when I wrote entity I realized that I have no idea how to map to two tables. Anyhow, please give me a sec and I will post what I have — Amer M.
– Amer M., Commented Sep 12, 2020 at 11:25

Pablo Fradua · Accepted Answer · 2020-09-12 12:56:55Z

1

You need:

@MappedSuperclass public class ClassWithTheFields{ \\Not annotated with @Entity @Id private Integer Id; ... }

@Entity public class EntityClass extends ClassWithTheFields{}

@Entity public class AnotherEntityClass extends ClassWithTheFields{}

This way, both classes extending ClassWithTheFields will have the same fields, but will be mapping different tables.

You just need to put all the common fields in a class annotated with @MappedSuperclass, but not@Entity, and then extend this class in other classes annotated with @Entity.

answered Sep 12, 2020 at 12:56

Pablo Fradua

3991 gold badge4 silver badges16 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Zurahid Omeragić · Accepted Answer · 2020-09-12 17:26:04Z

1

You should go with @MappedSuperclass. It's the easiest choice for you.

answered Sep 12, 2020 at 17:26

Zurahid Omeragić

111 bronze badge

Comments

SternK · Accepted Answer · 2020-09-12 19:51:05Z

You can try to use @SecondaryTable annotation.

Something like this:

@Entity
@Table(name = "MY_PAYMENT")
@SecondaryTable(name = "MY_PAYMENT_DETAILS",
    pkJoinColumns = @PrimaryKeyJoinColumn(name = "pd_payment_id"))
public class Payment {

   @Id
   @Column(name = "p_id")
   private Long id;
   
   @Column(name = "p_first_name")
   private String firstNname;

   // ...
   
   @Column(name = "pd_amount", table = "MY_PAYMENT_DETAILS")
   private double amount;
}

This is assumed that you have the following schema:

create table MY_PAYMENT
(
   p_id number,
   p_first_name varchar(200),
   CONSTRAINT MY_PAYMENT_PK PRIMARY KEY(p_id)
);

create table MY_PAYMENT_DETAILS
(
   pd_payment_id number,
   pd_amount number,
   CONSTRAINT MY_PAYMENT_DETAILS_PK PRIMARY KEY(pd_payment_id),
   CONSTRAINT MY_PAYMENT_DETAILS_FK foreign key(pd_payment_id) references MY_PAYMENT(p_id)
);

See also this section of hibernate documentation.

Collectives™ on Stack Overflow

Hibernate: Multiple tables, same object

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related