Lazy Initialization Hibernate in Struts Spring Hibernate - spring

Question

I save current user in session, and when i use current user (example:user.getRole.getRoleName()), i got LIE. How can i solve this problem, my code is like this
Controller:
public String home(){
Users users = userService.getCurrentUser();
if(users.getRole().getRoleName().equals("admin")){ //causing LIE
....
}
UserService :
#Override
public Users getCurrentUser(){
session = ActionContext.getContext().getSession();
return (Users) session.get("user");
}
But, when i change userService.getCurrentUser() to be like this, error is resolved but i think this is not a right manner, because it need connection to database every time i use current user.
#Override
public Users getCurrentUser(){
session = ActionContext.getContext().getSession();
return daoManager.getDetailUser(((Users) session.get("user")).getUsername());
}
DaoManager.getDetailUser is like this
#Override
public Users getDetailUser(String username) {
try {
Users user = (Users)sessionFactory.getCurrentSession().createQuery("SELECT U FROM Users U WHERE U.username=:USERNAME")
.setParameter("USERNAME", username)
.uniqueResult();
return user;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
is there any other better way to solve this problem? Thank you.

Answer 1

The easiest way to resolve this is just to access the lazy fetched field before the session is closed:
#Override
public Users getCurrentUser(){
session = ActionContext.getContext().getSession();
Users user = (Users) session.get("user");
user.getRole(); //Accessed to resolve lazy field
return user;
}
I do not recommend FetchType.EAGER. With that you cannot control access, it is always fetched whether you need it or not.. Add a few EAGER fields to your data model and suddenly your fetching the entire database for the simplest requests..
For queries you can also use JOIN FETCH

Answer 2

The most likely explanation will be that Spring closes the current session when you are exiting the service layer (UserService), however, after this happens, because Hibernate attempts to lazily load the children objects to avoid unnecessarily loading data (see also What is lazy loading in Hibernate?).
To avoid this, you could either ensure that hibernate does not do lazy loading by specifying fetch=FetchType.EAGER on the role, or use the OpenSessionInView pattern (however, that's sometimes considered an antipattern, see Why is Hibernate Open Session in View considered a bad practice?).