Internal server error upon returning JPA entity with XML annotations

Question

I have made a simple CRUD app for learning purposes that uses webservices (with jersey), EJBs and JPA (eclipse link + mysql). I've at first obviously made an entity class called User and tried to return it, after searching for it for example by ID (with namedquery) like that:

public User findById(Integer id) {
    return em.createNamedQuery("User.findById", User.class).setParameter("id", id).getSingleResult();
}

and it works fine (just the finding bit), but upon returning it with:

@GET
@Path("/{id}")
@Produces(MediaType.APPLICATION_XML)
public User find(@PathParam("id") String id) {
    return db.find(id);
}

(there is another layer between dao and this above) it always produces an internal server error, without any errors in glassfish console.

Response:
status: 500 Internal Server Error
Date: Mon, 02 Mar 2015 07:02:08 GMT
Server: GlassFish Server Open Source Edition 4.1
Connection: close
X-Powered-By: Servlet/3.1 JSP/2.3 (GlassFish Server Open Source Edition 4.1 Java/Oracle Corporation/1.7)
Content-Length: 1154

The server encountered an internal error that prevented it from fulfilling this request.

My entity class was as follows:

import java.io.Serializable;
import java.lang.Integer;
import java.lang.String;

import javax.persistence.*;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@Entity
@Table(name="Users")
@NamedQueries({ @NamedQuery(name="User.getAll", 
                query="SELECT u FROM User u"),
                @NamedQuery(name="User.findByName", 
                query="SELECT u FROM User u WHERE u.name = :name"),
                @NamedQuery(name="User.getCount",
                query="SELECT COUNT(u) FROM User u"),
                @NamedQuery(name="User.findById", 
                query="SELECT u FROM User u WHERE u.id = :id"),
            }) 
@XMLRootElement
public class User implements Serializable{
    @Id
    @Column(name="Id")
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer id;

    @Column(name="Name")
    private String name;
    private static final long serialVersionUID = 1L;

    public User() {

    }   
    public int getId() {
        return this.id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setId(Integer id) {
        this.id = id;
    }   
    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + "]";
    }

}

Now I have tried to extract interface from User, and call it user, rename entity to UserEntity and create a new class implementing User interface - UserXML. It's basic, just id/name fields with getters, setters and XML annotations. When I return user I now do something like this:

public User findById(Integer id) {
    UserEntity user = em.createNamedQuery("User.findById", UserEntity.class).setParameter("id", id).getSingleResult();
    System.out.println("returning "  + user.toString());
    User userxml = new UserXML();
    userxml.setId(user.getId());
    userxml.setName(user.getName());
    return userxml;
}

And it works perfectly. Why? What did I do wrong in my first approach?

Internal server error upon returning JPA entity with XML annotations

0 Answers0