find(Class,id) and JPQL get different object (JPA)

Aaron.Wang · **Joined:** Tue Feb 26, 2013 11:50 am **Posts:** 2

I used Hibernate 4.1.10.Final as the JPA provider, Spring and Spring MVC.

There are two entities.

Code:

@Entity
@Table(name = "a")
public class A{
@Id
private String id;

[color=#808040]
@OneToMany(mappedBy = "a", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private Set<B> bs;
[/color]
....
}

@Entity
@Table(name = "b")
public class B{
@Id
private String id;

[color=#808040]
@ManyToOne
@JoinColumn(name = "fk_a_id")
private A a;
[/color]
....
}

I need to get an A and it's bs, so i using find(A.class,id) of EntityManager.

Code:

A a1 =em.find(A.class, id);
a1.getBs().size();

Result is: the size of bs is zero. It means that there is no associated B.
But i'm sure that there are many associated Bs in the database and the data have been load from database while checking console.

While i used Query to get that :

Code:

Query query = em.createQuery("SELECT a FROM A AS a WHERE a.id = ?1",A.class);
query.setParameter(1, id);
A a= (A) query.getSingleResult();
a.getBs().size(); // = 22

This time the size is 22.

What's wrong?

Ajit Singh · **Joined:** Wed Feb 06, 2013 2:43 am **Posts:** 46

Can you please try this in your OneToMany mapping :

private Set b = new HashSet(0); // Declaration

//Getter and setter
@OneToMany
@JoinColumn(name = "b")
public Set getB() {
return a;
}
public void setB(final Set b) {
this.b = b;
}

Aaron.Wang · **Joined:** Tue Feb 26, 2013 11:50 am **Posts:** 2

Ajit Singh wrote:

Can you please try this in your OneToMany mapping :

private Set b = new HashSet(0); // Declaration

//Getter and setter
@OneToMany
@JoinColumn(name = "b")
public Set getB() {
return a;
}
public void setB(final Set b) {
this.b = b;
}

Thanks for your answer.
With this way, it also can not get bs.