Using saveOrUpdate() in Hibernate creates new records instead of updating existing ones

Question

I have a class User

class User { 
  int id;
  String name;
}

where id is native generator in User.hbm.xml and name is primary-key in DB.

In my database I saved some information about Users.

Than I want to connect with this information about User.

For example in my DB I have a row INSERT INTO User VALUES ('Bill');

Main.java

User bill = new User();
bill.setName("Bill");
session.saveOrUpdate(bill);

This code always tries to insert a new Bill row into the table rather than update the existing Bill row.

Answer 1

This code always trying insert bill to database , rather than update when row about Bill exists in DB...

From the section 10.7. Automatic state detection of the Hibernate core documentation:

saveOrUpdate() does the following:

• if the object is already persistent in this session, do nothing
• if another object associated with the session has the same identifier, throw an exception
• if the object has no identifier property, save() it
• if the object's identifier has the value assigned to a newly instantiated object, save() it
• if the object is versioned by a <version> or <timestamp>, and the version property value is the same value assigned to a newly instantiated object, save() it
• otherwise update() the object

When you do:

User bill = new User();
bill.setName("Bill");
session.saveOrUpdate(bill);

This newly created instance does not have any identifier value assigned and saveOrUpdate() will save() it, as documented. If this is not what you want, make the name the primary key.