I have simple 3 tables:
Users
-id
-name
Addresses
-id
-user_id //FK
-location
Phone
-id
-number
-address_id //FK
Thus, annotations applied to each entity class would look like:
Users
@OneToMany(cascade = CascadeType.ALL, mappedBy = "user")
private List<Addresses> addresses;
Addresses
@ManyToOne()
@JoinColumn(name = "user_id")
private Users user;
@OneToMany(mappedBy = "address")
private List<Phone> phone;
Phone
@ManyToOne()
@JoinColumn(name = "address_id")
private Addresses address;
The annotation above should create relationship:
users (1) ----- (n) addresses (1) ------ (n) phone
Then I created some test data in MySQL and tried to run test to see if query result that returns "users" would include reference to addresses and phone.
I've tried with 2 table only using users and addresses and got result ok.
Now that I added "phone" table which is 3rd table then I'm getting error shown below. Is this really right way to join 3 or more tables?
Test code
try {
//get entity manager
String WEB_PU = "NoJSFPU";
EntityManagerFactory factory = Persistence.createEntityManagerFactory(WEB_PU);
EntityManager em = factory.createEntityManager();
//run query
List<Users> usersList = em.createQuery("SELECT u FROM Users u").getResultList();
//loop to print out each result
for(Users item : usersList) {
//display user info
System.out.println(item.getId() + " " + item.getFirstname());
List<Addresses> addrs = item.getAddresses();
for(Addresses ad : addrs) {
//display address info
System.out.println("Address:::" + ad.getLocation());
List<Phone> pho = ad.getPhone();
for(Phone p : pho) {
//display phone info
System.out.println("phone#" + p.getNumber());
}
}//end inner for
}//end outer for
System.out.println("==========================");
}
catch(Exception e) {
System.out.println("seriously wtf: " + e.toString());
System.exit(1);
}
Error
Exception Description: predeploy for PersistenceUnit [NoJSFPU] failed.
Internal Exception: Exception [TOPLINK-7250] (Oracle TopLink Essentials - 2.0.1 (Build b09d-fcs (12/06/2007))): oracle.toplink.essentials.exceptions.ValidationException
Exception Description: [class local.test.session.Addresses] uses a non-entity [class local.test.session.Phone] as target entity in the relationship attribute [private java.util.List local.test.session.Addresses.phone].
I figured out. Had to specify by using @JoinTable annotation.
Now If I run the test code, data from all 3 tables can be obtained :D
Addresses
@ManyToOne
@JoinTable(name = "Addresses", joinColumns = {@JoinColumn(name="user_id",
referencedColumnName = "user_id") } )
private Users user;
Phone
@ManyToOne
@JoinTable(name = "Phone", joinColumns = {@JoinColumn(name="address_id",
referencedColumnName = "address_id") } )
private Addresses address;