Model | First entity | Intro

MappedSuperclass

We use @MappedSuperclass for common properties across many entity beans.

It is common to have a mapped superclass with @Id, @Version and @WhenModified properties like the example below and common for the mapped superclass to extend Model.

java
kotlin

package org.example.domain;

import io.ebean.Model;
import io.ebean.annotation.WhenCreated;
import io.ebean.annotation.WhenModified;

import jakarata.persistence.Id;
import jakarata.persistence.MappedSuperclass;
import jakarata.persistence.Version;
import java.time.Instant;

/**
 * Base domain object with Id, version, whenCreated and whenModified.
 */
@MappedSuperclass
public abstract class BaseDomain extends Model {

  @Id
  long id;

  @Version
  Long version;

  @WhenCreated
  Instant whenCreated;

  @WhenModified
  Instant whenModified;

  // getters and setters
  ...

}

package org.example.domain

import io.ebean.annotation.WhenCreated
import io.ebean.annotation.WhenModified
import java.time.Instant
import jakarata.persistence.Id
import jakarata.persistence.MappedSuperclass
import jakarata.persistence.Version

@MappedSuperclass
open class BaseDomain : Model() {

  @Id
  var id: Long = 0

  @Version
  var version: Long = 0

  @WhenModified
  lateinit var whenModified: Instant

  @WhenCreated
  lateinit var whenCreated: Instant

}

Our entity beans then extend this to inherit the common properties.

...
@Entity
public class Customer extends BaseDomain {

  String name;

  LocalDate registered;
  ...

package org.example.domain

import jakarata.persistence.Entity

@Entity
class Customer : BaseDomain() {

  var name: String? = null
}

Kotlin has multiple constructor styles. See here for more information on the preferred constructor style for entity beans.