Question

I try to get hibernate 4 running (shipped with JBoss AS 7) and deploy my application as EAR (persistence.xml iis in the META-INF of the EAR). Hibernate seems to run. I have two classes and is does not complain as long as I do not use one class inside the other.

I have a session:

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "sessions")
public class Session {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    public Long dbid;
    public String id;
    public User user; // This is problematic!

    public Session() {
    }

    public Session(User user) {
        this.id = generateID();
        this.user = user;
    }

    private String generateID() {
        return Long.toString((long) (Math.random() * 1000000000.0));
    }

    @Override
    public int hashCode() { [...] }

    @Override
    public boolean equals(Object obj) { [...] }
}

And I have a user

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "users")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    public Long dbid;
    public String name;
    public String password;

    public User() {
    }

    public User(String name, String password) {
        this.name = name;
        this.password = password;
    }

    @Override
    public int hashCode() { [...] }

    @Override
    public boolean equals(Object obj) { [...] }
}

If I start the server it complains:

Caused by: org.hibernate.MappingException: Could not determine type for: myproject.model.User, at table: sessions, for columns: [org.hibernate.mapping.Column(user)]
    at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:303)
    at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:287)
    at org.hibernate.mapping.Property.isValid(Property.java:215)
    at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:466)
    at org.hibernate.mapping.RootClass.validate(RootClass.java:267)
    at org.hibernate.cfg.Configuration.validate(Configuration.java:1285)

It does not complain if I remove public User user; from the session class.

Both classes are listed in the persistence.xml and I have tried:

1. generated getters/setters and place the annotations at the getters
2. generate hashCode and equals appropriately

What could I check additionally? What might be the problem?

Answer 1

Add the @ManyToOne annotation to the User member in your session class (assuming a single user can have multiple sessions in your database … if a user only ever has one extant session, you can use @OneToOne