What is the easiest way to create nested objects in Ebean?

Question

I need two classes of the Ebean model called States and Children. The State object may contain nested child objects (list of children).

Here is the main class of states,

@Entity
public class States extends Model {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @Constraints.Required(message = "stateName cannot be null")
    @Column(nullable = false)
    private String statename;

    @Column(nullable = true)
    private String url;

    @Column(nullable = true)
    private String parent;

    private List<Children> childrenList;
}

Here is the base class Children

@Entity
public class Children extends Model {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @Column(nullable = false)
    private String statename;

    @Column
    private String child;
}

What are the minimum changes that must be made for these classes to create state objects using Ebean ORM? I went through the mail

Ebean Query by OneToMany Relationship

But there were many changes suggested. I just want minimal changes.

Answer 1

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@Entity
public class States extends Model {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @Constraints.Required(message = "stateName cannot be null")
    @Column(nullable = false)
    private String statename;

    @Column(nullable = true)
    private String url;

    @Column(nullable = true)
    private String parent;

    @OneToMany(cascade = CascadeType.ALL)
    private List<Children> childrenList;
}

, ,

@OneToMany(cascade = CascadeType.ALL)

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play.evolutions.enabled = true

"application.conf". , SQL, "evolution.default", . "States" "".