Partial update

mcbi4kh2 · **Joined:** Thu Jun 12, 2008 10:48 am **Posts:** 24

Hibernate version: 3.2.6.ga

Is there a way apart from native SQL to persist partial object (i.e. just updating the fields with values in the object and not affecting other fields with null values)

for eg:
I have personInfo with below fields
username (this is the id/pk, I will always have this value in the object)
password
firstname
lastname
age
sex...so on

I want to update only 2-3 fields of this table. So can i use saveOrUpdate passing the partially populated personInfo object leaving all the other properties null in the object and unchanged in the db?

mmerder · **Posted:** Wed Feb 04, 2009 5:26 am

If you want to update only those fields, which have changed, you could use <class ... dynamic-update="true">

mcbi4kh2 · **Joined:** Thu Jun 12, 2008 10:48 am **Posts:** 24

I have added that and I get this error:

org.hibernate.exception.ConstraintViolationException: could not update: password

org.hibernate.util.JDBCExceptionReporter - Cannot insert the value NULL into column 'password', table 'person'; column does not allow nulls. UPDATE fails.

Any more suggestions?

mmerder · **Posted:** Wed Feb 04, 2009 5:42 am

How do you change your object? I guess, you are creating a new Object and populate just the fields you want to be changed. That is not going to work, as you need to fetch your entity, change the loaded one and then flush the session, so that hibernate is able to detect changed fields.

mmerder · **Posted:** Wed Feb 04, 2009 5:47 am

In case you are somehow not able to work on a loaded object, but still insist on only updating not-null fields:
You could create your own update-method, which checks for all non-null fields on a given object and then changes loaded one, e.g.

Code:

public void updatePartially(PersonInfo info)
{
  //get a session and start a transaction ...

  PersonInfo old = session.load(PersonInfo.class, info.getUserName());
  
  //look for not-nulls
  if(info.getFirstname() != null) old.setFirstname(info.getFirstname());

  //do that for all fields ...

  session.flush();
}

Rating is welcome. ;-)

mcbi4kh2 · **Joined:** Thu Jun 12, 2008 10:48 am **Posts:** 24

I get my object from Hibernate, pass it to my UI layer, and by the time it comes back it has changed completely and Hibernate knows nothing about it I suppose.
So I need to load the object from the db using my id, then how do I save the object with the values in my Object?

mcbi4kh2 · **Joined:** Thu Jun 12, 2008 10:48 am **Posts:** 24

oops, posted that before seeing your reply. Thanks very much

mmerder · **Posted:** Wed Feb 04, 2009 6:00 am

mcbi4kh2 wrote:

I get my object from Hibernate, pass it to my UI layer, and by the time it comes back it has changed completely and Hibernate knows nothing about it I suppose.

In that case use session.merge(), which reattaches your detached object to the new session.

Please rate me, if it helped you.

mcbi4kh2 · **Joined:** Thu Jun 12, 2008 10:48 am **Posts:** 24

If I use merge, Hibernate complains about firstname being null, it is null in my object but not in the db.

org.hibernate.util.JDBCExceptionReporter - Cannot insert the value NULL into column 'firstname'

mmerder · **Posted:** Wed Feb 04, 2009 6:52 am

Why is it null? I thought you load an object, pass it to the GUI-Layer, edit it and then pass it back. In that case you should not loose any information. What about the own updatePartially-method, mentioned above?

mcbi4kh2 · **Joined:** Thu Jun 12, 2008 10:48 am **Posts:** 24

That person thing is just something I made up for concisesness, I have about 45 different fields in my actual table. Some of them I dont need and so dont really want to pass them around my application.
I figured so long as I keep my Id then I would be able to update the non-null values.

Looks like thats not possible so I'll try and write a more generic method of what you mentioned earlier.
Many Thanks