The id is null

mateamargo · **Joined:** Tue Sep 05, 2006 2:36 pm **Posts:** 24

Hibernate version: 3

Mapping documents:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

<class name="User" table="users">
<id name="id" column="userId">
<generator class="native" />
</id>
<property name="name"/>
<property name="lastName"/>
</class>

</hibernate-mapping>

The problem is that when I get an instance of User, the id property remains in null, the name and lastName properties are getted correctly.
The userId filed in the database is a PK Autonumeric, so is never null.

Is this behavior ok, or maybe the id element in the mapping is wrong?

bengrant · **Joined:** Wed Sep 13, 2006 7:24 am **Posts:** 26

this is right,

we have this in our system

The id stays Null until it saved to the database, then the object gets a Id from the database when you save/flush the item

mateamargo · **Joined:** Tue Sep 05, 2006 2:36 pm **Posts:** 24

Ok, and how could I get the whole object included the id in a session.get call?

bengrant · **Joined:** Wed Sep 13, 2006 7:24 am **Posts:** 26

mateamargo wrote:

Ok, and how could I get the whole object included the id in a session.get call?

Object needs to be saved first. once you have saved the object the object should have the id set

so if i do

Code:

Person x = new Person("me","somewhere);
session.save(x);
x.getId()  

Should return something

if not the you can do

Code:

session.update(x);

which will update the object with the details from the its store.

mateamargo · **Joined:** Tue Sep 05, 2006 2:36 pm **Posts:** 24

The thing is that my object is already on the database, I don't need to save it or update it.

I'm using HQL query to retrieve a list of instances of User, and I need that each one has an id (previously I said session.get, but it was a mistake).

My HQL query is:

Code:

session.beginTransaction();
session.getTransaction().begin();
   
Query q = session.createQuery("from User");

return q.list();

But when I iterate through the list, I always get null when I try to read the id.

batmat · **Posted:** Wed Dec 13, 2006 2:20 pm

mateamargo wrote:

The problem is that when I get an instance of User, the id property remains in null, the name and lastName properties are getted correctly.
The userId filed in the database is a PK Autonumeric, so is never null.

Is this behavior ok, or maybe the id element in the mapping is wrong?

What do you mean by "when I get an instance" ? Retrieving an instance from the db, though the session object or a brand new one created with "new YourObject()" for example ?

As bengrant said, if the object is newly created by you, this is totally normal that the id is null with the generator you specified. Even more : this is a requirement. If you put something in the id, you'll get an error because Hibernate will try and find a corresponding instance with the corresponding primary key in the db.

If the id is null after retrieving from the db, this would be very odd. Please let us know.

alanmehio · **Posted:** Wed Dec 13, 2006 2:35 pm

My question is what is the database you are using.
For example if it is a sybase the PK autogenerator should be like

id numeric(5) identity constraint p_contraint_xxx primary key

if you work with Oracle so for autogenerartor ( native generator)
id BIGINT not null generated by default as identity

When you save the transient object
can you find out if the below "id" returns a vlaue

Person x = new Person("me","somewhere);
Serializable id = session.save(x);
System.out.println(id) // Do you see a value ????
x.getId()

mateamargo · **Joined:** Tue Sep 05, 2006 2:36 pm **Posts:** 24

I'm trying to retrieve a list of objects.

I'm using HQL (as I said before).

My code is something like this:

Code:

List<User> users = User.getList();

for(User user: users){
  System.out.println("The user ID is: " + user.getId());
}

The getList method:

Code:

public static List getList(){

session.beginTransaction(); 
session.getTransaction().begin(); 
    
Query q = session.createQuery("from User"); 

return q.list();

}

All the Id's are null.

PS: The database ser is MySQL 5 running on WinXP.

bengrant · **Joined:** Wed Sep 13, 2006 7:24 am **Posts:** 26

bengrant wrote:

mateamargo wrote:

Ok, and how could I get the whole object included the id in a session.get call?

Object needs to be saved first. once you have saved the object the object should have the id set

so if i do

Code:

Person x = new Person("me","somewhere);
session.save(x);
x.getId()  

Should return something

if not the you can do

Code:

session.update(x);

which will update the object with the details from the its store.

sorry i meant to type

Code:

session.refresh(x);

mateamargo · **Joined:** Tue Sep 05, 2006 2:36 pm **Posts:** 24

bengrant: The problem is when I get a list of objects. Should I perform session.refresh on each one in the list?

Ananasi · **Posted:** Thu Dec 14, 2006 10:34 am

Can we see your POJO please.

mateamargo · **Joined:** Tue Sep 05, 2006 2:36 pm **Posts:** 24

Ananasi wrote:

Can we see your POJO please.

Code:

public class User{

private Long id;
private String name;
private String lastName;

public User(){
}

public Long getId(){
  return id;
}

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

public String getName(){
  return name;
}

public void setName(String name){
  this.name = name;
}

public String getLastName(){
  return lastName;
}

public void setLastName(String lastName){
  this.lastName = lastName;
}

}

This is my class without the getList method that I previously posted.
But basically the idea is to return a list of users (that is working ok), but all the id's are null.

Ananasi · **Posted:** Thu Dec 14, 2006 11:36 am

That is pretty odd. Can you put in type="java.lang.Long" in the id mapping and see if that helps. If not, turn on debug logging and see how the entities are being hydrated.

mateamargo · **Joined:** Tue Sep 05, 2006 2:36 pm **Posts:** 24

I changed it, but I'm still having the same issue.

The only way I found to resolve this is using a property that I called "dummyId" and points to same field that the original Id but with the attributes insert="false" and update="false".

Is this a bug? could any of you try to reproduce this and tell me if you are having the same problem?

Ananasi · **Posted:** Thu Dec 14, 2006 12:45 pm

I can try to reproduce, please post the DDL so that I can recreate the database exactly as you have it.