How to query Embedded class in Hibernate?

Question

I have an Embeddable model (It is not an Entity), which has only getters(I do not want keep setters, because it's attributes are fixed.) I have this model embedded in another entity.

Now, my requirement is, When I do GET queries in the entity class, I would like to use some parameters defined in the "Embeddable model" . Now the problem is, since Embeddable model does not have seperate table, I could not query the database.

How can I approach this in Hiberanate?

Embeddable class

@Embeddable
public class Observation  {


    @Column(name = "CREATED")
    private LocalDateTime created;

   @NotNull
    @Column(name="O_CODE")
    private String o_code;

    public String getCode() {
        return o_code;
    }
   public String getCreated() {
        return created;
    }
}

Entity class

@Table(name = "field_observation", uniqueConstraints = @UniqueConstraint(columnNames = "code"))
public class FieldObservation {

 private Long id;

  @Embedded
    private Observation observation = null; 


    getObservation{}
    setObservation{}

......... }

GET call

public Response getItems(
    @QueryParam("o_code") java.lang.String o_code,
    @QueryParam("id") java.lang.Long id,
    @QueryParam("format") @DefaultValue("list") String format
) {
----  //How to query database to get Observation entry?

Answer 1

Hibernate : Supports collections of embeddables through the @CollectionOfElements annotation and JPA 2.0 ElementCollection mapping.

Embeddable objects cannot be queried directly, but they can be queried in the context of their parent. Typically it is best to select the parent, and access the embeddable from the parent. This will ensure the embeddable is registered with the persistence context . If the embeddable is selected in a query, the resulting objects will be detached , and changes will not be tracked.

Ex. select fieldObservation.o_code from FieldObservation fieldObservation where id= :param .