Hibernate custom class mapping

Question

When I fech users using this code, it works as desired.

 public List<Users> getActiveUsers(User user) {
    EntityManager entityManager = getEntityManager();
   List<User> Users = new ArrayList();
    try {
        users = entityManager.createQuery("select e from User e where  e.deleted = :deleted", User.class)
                .setParameter("deleted", false)                 
                .getResultList();
    } finally {
        entityManager.close();
    }
    return users;
}

But if I try to get only one user using th following code, it fails.

User user = (User) entityManager.createQuery("select e from User e where  e.deleted = :deleted")
                .setParameter("deleted", false)+                 
                .getSingleResult();

I can't get a mapped user, the excepction is: "can't convert com.project.model.User to com.project.model.User"

Can you try using `entityManager.createQuery(query, User.class)`? Where do you deploy this? — Arturo Volpe, May 12 '17 at 12:12
I have tried it, same result. Where I deploy? Not sure if I understand, it is in localhost and the method is being called in a userRepositoryCustom class — Marcel Caferati, May 12 '17 at 12:18
What application server are you using, this seems a problem related to a classloader. Also try adding to your query "setMaxResults(1)". — Arturo Volpe, May 12 '17 at 12:22
This is the error I get: `Can not pass an instance of "class com.project.model.User (loaded by instance of sun.misc.Launcher$AppClassLoader(id=8597))" to an instance of "class com.project.model.User (loaded by instance of org.springframework.boot.devtools.restart.classloader.Restar‌tClassLoader(id=1241‌4))"` — Marcel Caferati, May 14 '17 at 00:12

ℛɑƒæĿᴿᴹᴿ · Answer 1 · 2017-05-12T12:32:30.303

1

You forgot to put the class type User.class:

entityManager.createQuery("SELECT u FROM User u where  u.deleted = :deleted", User.class)
             .setParameter("deleted", false).getSingleResult();

Your method:

 public User getActiveUser(User user) {
    EntityManager entityManager = getEntityManager();      
    try {
        User user = (User) = entityManager.createQuery
                           ("SELECT u FROM User u WHERE u.deleted = :deleted", User.class)
                           .setParameter("deleted", false).getSingleResult();
    } finally {
        entityManager.close();
    }
    return user;
}

Look on first example, you use Users class and on second User (without S in the end)
You need to be care with this query, because they may be returned more than one record

edited May 12 '17 at 12:32

answered May 12 '17 at 12:18

ℛɑƒæĿᴿᴹᴿ

4,983
4
38
58

I have tried with both, casting (User) and adding User.class – Marcel Caferati May 12 '17 at 12:19
I have tried that, and this is the error I get `Can not pass an instance of "class com.project.model.User (loaded by instance of sun.misc.Launcher$AppClassLoader(id=8597))" to an instance of "class com.project.model.User (loaded by instance of org.springframework.boot.devtools.restart.classloader.RestartClassLoader(id=12414))"` – Marcel Caferati May 14 '17 at 00:06

score 1 · Accepted Answer · edited May 23 '17 at 12:26

1

Apparently there was nothing wrong with the code. What I found out to be the problem was the same as this guy:

A classloader proplem related to spring-boot-devtools

however, the .properties file with the dozer reference did not work for me. I managed to get my code up and running by removing spring-devtools from the project. Guess I can live without live reload!

edited May 23 '17 at 12:26

Community

1
1

answered May 14 '17 at 01:26

Marcel Caferati

184
11

Hibernate custom class mapping

2 Answers2