I have a "strange" behavior, with list properties of any kind of entity.
When i try to set a non empty list to a retrieved entity that has a list
value with null (because is not fetched) the entity doesnt "reflect" the
new non-empty values that i set.
Steps
1. Retrieve any entity (ex. user) from database in an ejb with criterias.
2. The retrieved entity has a OneToMany attribute (roles) by default is
lazy thats why if i dont do a fetch (i dont) the list is null
3. Then try to fill the role list with a NON-EMPTY list
4. Here the list that i set has values but the user list has a null in the
roles list attribute even though i set it in the step 3
I dont know why this is happening, the only way i could fix this is cloning
(using SerializationUtils from Apache commons.lang3) the user entity (see
the steps) and with this work, but i dont know why.
1. Retrieve any entity (ex. user) from database in an ejb with criterias.
2. Clone retrieved entity and asig to new one User clonedUser =
SerializationUtils.clone(originalRetrivedUser);
3. Then try to fill the role list with a NON-EMPTY list to the clonedUser
4. The list of clonedUser has the correct values
Why i need to clone? why i cannot set a list to the entity if is not cloned?
Im using Apache TomEE 1.6.0-SNAPSHOT (with the openjpa version embedded)
Scenario:
***** ENTITIES *****
@Entity
public class User implements Serializable{
@Id
private int id;
private String userName;
private String password;
@OneToMany(mappedBy = "user")
private List<Role> roles;
//getters and setters..
}
@Entity
public class Role implements Serializable{
@Id
private int id;
private String roleName;
@ManyToOne
@JoinColumn(name = "user_id")
private User user;
//getters and setters..
}
**** EJB CLASS ****
@Stateless
public class MyEJB{
@PersistenceContext(unitName ="ANY_NAME")
private EntityManager em;
public User getUserWithRoles(){
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<User> cq = cb.createQuery(User.class);
Root<User> root = cq.from(User.class);
cq.where(cb.equal(root.get(User_.userName),"john"));
User userJohn = em.createQuery(cq).getSingleResult(); // if i want
this work i have to do User userJohn =
SerializationUtils.clone(em.createQuery(cq).getSingleResult()); [1*]
//i will create a list of role just for try to set any role the
userJohn
List<Role> roleList = new ArrayList<Role>(2);
roleList.add(new Role(1,'ADMIN'); //creating and adding role 1
roleList.add(new Role(2,'DEVELOPER');//creating and adding role 2
//setting the list of roles created to the user, as you can see the
list has 2 values but the value roles of userJohn always is set to null, my
setters and getters are correct
userJohn.setRoles(roleList);
return userJohn;
}
}
*** MANAGED BEAN ****
@Named
public class MyBean implements Serializable{
@EJB
private MyEJB ejb;
public void anyMethod(){
User user = ejb.getUserWithRoles();
user.getRoles(); //<---- HERE THE LIST IS ALWAYS NULL but if i use
clone in the ejb method (see 1*) i can get the corrected values.
}
}
I know i can get the values fetching but im trying to not do it
