# attach

## Purpose

Attaches a detached domain instance to the Hibernate session bound to the current thread

## Examples

    def b = Book.get(1)
    b.title = "Blah"
    b.save(flush:true)b.discard()…
    if(!b.isAttached()) {
    	b.attach()
    }

## Description

Grails uses Hibernate which manages each persistent object in a persistence session. A new session is created per request and is closed at the end of the request. If an object is read from the session and placed into a web scope such as the HttpSession it is seen as detached, since the persistence session has been closed. You can use the attach() method to re-attach an existing persistent instance to the persistence session of the current request.