If this can not be done in JPA I will appreciate it if someone can let me know.
On Mon, Jun 23, 2014 at 9:24 AM, Mansour Al Akeel <mansour.alak...@gmail.com > wrote: > John, > > the classes are not in the same persistence unit. So even getReference > will not work. > > Thank you. > > > > On Mon, Jun 23, 2014 at 7:49 AM, Boblitz John <john.bobl...@bertschi.com> > wrote: > >> > -----Original Message----- >> > From: Mansour Al Akeel [mailto:mansour.alak...@gmail.com] >> > Sent: Montag, 23. Juni 2014 10:23 >> > To: users >> > Subject: How to map an ID of a foreign key as a field >> > >> > I am looking to map a field in the owner entity to the ID of the target >> entity. >> > For example, taking the Employee -> Department mapping: >> > >> > class Employee { >> > >> > private String name ; >> > >> > private String depId ; >> > >> > private Department department ; >> > >> > @ManyToOne(fetch = FetchType.EAGER, optional = false) >> > @JoinColumn(name = "dep_id", referencedColumnName = "id", insertable >> > = false, updatable = false) public Department getDepartment(){ return >> > this.department ; } >> > >> > >> > public void setDepId(String depId){ >> > this.depId = depId; >> > } >> > ... >> > >> > } >> > >> > My Question is, how can I set the Deparment by setting only its dep_id >> in the >> > employee object, and keep the foreign key constraints when the tables >> are >> > created ?? >> > >> > For example: >> > >> > Employee emp = new Employee() ; >> > emp.setId("SOME_ID_1") ; >> > emp.setDepId("FINANCE"); >> > >> > em.persist(emp); >> > >> > and if there's no FINANCE record in the department table, then we have >> an >> > constraints violation. >> > >> > At the same time I don't want to have setters for Department Entity. >> Only its >> > ID. >> > >> > Thank you. >> >> >> >> Hello Mansour, >> >> Not sure why you would need the extra Emplyoee.depId. >> >> I would do what you would like this way: >> >> Employee emp = new Employee() ; >> emp.setId("SOME_ID_1") ; >> emp.setDepartment(em.getReference(Employee.class, "FINANCE"); >> em.persist(emp); >> >> >> From the JavaDoc: >> <T> T getReference(java.lang.Class<T> entityClass, java.lang.Object >> primaryKey) >> Get an instance, whose state may be lazily fetched. If the requested >> instance does not exist in the database, the EntityNotFoundException is >> thrown when the instance state is first accessed. (The persistence provider >> runtime is permitted to throw the EntityNotFoundException when getReference >> is called.) The application should not expect that the instance state will >> be available upon detachment, unless it was accessed by the application >> while the entity manager was open. >> >> Hope this helps. >> >> >> John >> > >
