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copied!<p>You don't need to use a discriminator. You can use inheritance using the "Table per class" approach. Here's what you do.</p> <ol> <li>Define class "Resource" that has "id" property which is an id.</li> <li>Define two subclasses, "Image" and "Video" that extend Resource and add additional properties - in your example, "imageType" and "videoType".</li> <li>Define class "Action" that has a @ManyToOne to Resource. If you want the "resourceType" property here as you described in your post, you can have it, but it's completely unnecessary to get things to work.</li> <li>I'm not sure what type of id generation (if any) you want or what type of cascading from Action to Resource, so for simplicity's sake I assumed none for both of these.</li> </ol> <p>With this approach, you'll get 3 tables in the database.</p> <p>Here's the shell of an implementation:</p> <pre><code>@Entity @Inheritance (strategy=InheritanceType.TABLE_PER_CLASS) public abstract class Resource { @Id @Column(name="ID") private String id; public Resource() {} public Resource(String id) { this.id = id; } ... // getters and setters } @Entity /* Table per Concrete Class */ @Table (name="Image") public class Image extends Resource { private String imageType; // Other properties unique to Image public Image() {} public Image(String id) { super(id); } public Image(String id, ...) { super(id); .... // setters } ... // getters and setters } /* Table per Concrete Class */ @Table (name="Video") public class Video extends Resource { private String videoType; // Other properties unique to Video public Video() {} public Video(String id) { super(id); } public Video(String id, ...) { super(id); .... // setters } ... // getters and setters } </code></pre> <p>With this approach, the following unit test shows the desired behavior:</p> <pre><code>Image image = new Image("i1", "imageType"); Video video = new Video("v1", "videoType"); Action imageAction = new Action("imageAction", image, "image"); Action videoAction = new Action("videoAction", video, "video"); manager.persist(image); manager.persist(video); manager.persist(imageAction); manager.persist(videoAction); manager.getTransaction().commit(); ... manager.getTransaction().begin(); System.out.println("********** Actions and Resources"); List<Action> result1 = manager.createQuery( "from Action" ).getResultList(); for ( Action a : result1 ) { System.out.println(a); } manager.getTransaction().commit(); </code></pre> <p>Implementing toString() for all of these classes, the following output is produced:</p> <p>Hibernate: create table Action (NAME varchar(255) not null, RESOURCE_TYPE varchar(255), RESOURCE_ID varchar(255), primary key (NAME)) Hibernate: create table Image (ID varchar(255) not null, imageProperty varchar(255), primary key (ID)) Hibernate: create table Video (ID varchar(255) not null, videoProperty varchar(255), primary key (ID))</p> <p><em><strong></em>****</strong> Actions and Resources Action( name=imageAction resource=Image( id=i1 imageType=imageType) resourceType=image) Action( name=videoAction resource=Video( id=v1 videoType=videoType) resourceType=video)</p> <p>Hope this helps to answer your question.</p> <p>Sarah</p>

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