def b = Book.get(1)
b.title = "Blah"
b.save(flush:true)
b.discard()
...
if (!b.isAttached()) {
b.attach()
}attach
Purpose
Associates a "detached" domain instance with the current Hibernate session
Examples
Description
Hibernate manages persistent instances in a persistence Session. A new Session is created per request and is closed at the end of the request. If an object is retrieved from the Session and placed into a web scope such as the HttpSession it will be "detached" from the Hibernate Session once the Session is closed and discarded. You can use the attach() method to re-attach an existing persistent instance to the persistence Session of the current request.