[jboss-user] [EJB 3.0] - Generics and Composite Keys
I have a situation where a set of entities share a similar composite key class; rather
than create a new PK class for each entity, I wanted to genericise the PK.
Here's my generic PK class:
| @Embeddable
| public class LanguagePK<T> implements Serializable {
|
| private T describes;
|
| private String code;
|
| @Column(name = "LANG_CODE")
| public String getCode() {
| return this.code;
| }
|
| public void setCode(String code) {
| this.code = code;
| }
|
| public T getDescribes() {
| return this.describes;
| }
|
| public void setDescribes(T described) {
| this.describes = described;
| }
| }
|
...and here's a sample entity that embeds it (Foo is another entity)
| @Entity
| @Table(name = "FOO_LANG")
| public class FooLanguage implements Serializable{
| LanguagePK<Foo> pk;
|
| @EmbeddedId()
| @AttributeOverrides( { @AttributeOverride(name = "describes", column =
@Column(name = "FOO_ID")) })
| public LanguagePK<Foo> getPk() {
|
| if (pk == null) {
| pk = new LanguagePK<Foo>();
| }
|
| return pk;
| }
|
| public void setPk(LanguagePK<Foo> pk) {
| this.pk = pk;
| }
|
| @Transient
| public Foo getFoo() {
| return getPk().getDescribes();
| }
|
| public void setFoo(Foo e) {
| getPk().setDescribes(e);
| }
|
| @Transient
| public String getCode() {
| return getPk().getCode();
| }
|
| public void setCode(String code) {
| getPk().setCode(code);
| }
| }
|
I'm getting the "Property X has an unbound type and no explicit target
entity" exception when I try to use it.
| [testng] javax.persistence.PersistenceException: java.lang.IllegalStateException:
Property describes has an unbound type and no explicit target entity.
| [testng] at
org.hibernate.ejb.Ejb3Configuration.createEntityManagerFactory(Ejb3Configuration.java:217)
| [testng] at
org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:114)
| [testng] at
javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:37)
| [testng] at
javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:27)
|
I've poked around, but I haven't found any example code on how to do something
like this. Am I'm trying to do something I shouldn't?
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