JPA: How can I Select @Embeddable Class

Question

I will select all the columns from @Embeddable Class Certification. But i cann't select it. how can i do select the Embeddable class.

@Entity
public class Department implements Serializable {


  private static final long serialVersionUID = 1L;
  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  private Long id;
  private String name;

  @ElementCollection
  @CollectionTable(name = "Certification", joinColumns = {@JoinColumn(name="user_id")})
  private List<Certification> certifications = new ArrayList<Certification>();

  public List<Certification> getCertifications() {
      return certifications;
  }

  public void setCertifications(List<Certification> certifications) {
      this.certifications = certifications;
  }


  public String getName() {
      return name;
  }

  public void setName(String name) {
      this.name = name;
  }

  .....

@Embeddable Class Certification

@Embeddable
public class Certification{

  private String name;
  private String certArt;

  public String getName() {
      return name;
  }

  public void setName(String name) {
      this.name = name;
  }



  public String getCertArt() {
      return certArt;
  }

  public void setCertArt(String certArt) {
      this.certArt = certArt;
  }

  ......

If i run the ResultService i get the following exception:

Caused by: java.lang.IllegalArgumentException: An exception occurred while creating a query in EntityManager: Exception Description: Error compiling the query [select c from Certification c]. Unknown entity type [Certification].

How can i select the @Embeddable Class?

Answer 1

You would need to retrieve Certification via the real Entity class ie Department . One example query could be as below:

   select cer from Department dep join dep.certifications cer

Alternatively, you may want to retrieve qualifying Department entities and then fetch certifications using them.