How to create hibernate composite key using annotations

Question

I am trying to use hibernate annotations to insert data to a MySQL database table which doesn't have a primary key defined.

However the fact is 2 fields of that table together are unique in the table.how can i achieve the same using hibernate annotation?.

here is my code..

 @Entity  @Table(name = "RolesMenuItems")     public class RolesMenuItems {         @Column(name = "RoleID")        private String roleID;         @Column(name = "MenuItemID")        private String menuItemID;   /*setter getter methods */  } 

Answer 1

You can use @Embeddeble and @EmbeddedId to create a composite key and map it with your Entity. For example:

@Embeddable public class RolesMenu {     @Column(name = "RoleID")     private String roleID;      @Column(name = "MenuItemID")     private String menuItemID;      //getter, setter methods }   @Entity  @Table(name = "RolesMenuItems")  public class RolesMenuItems {       @EmbeddedId      private RolesMenu roleMenu;    /*setter getter methods */  } 

Then use RolesMenuItems in your Java code to persist entities in usual way.

Reference: http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html_single/#d0e535

Edit: To persist the entity:

RolesMenu roleMenu = new RolesMenu(); roleMenu.setRoleID(...); roleMenu.setMenuItemID(...);  RolesMenuItems roleItem = new RolesMenuItems(); roleItem.setRoleMenu( roleMenu );  em.persist(roleItem);