grails composite key update - grails

Question

I have a legacy database and I'm using Grails. Mistake #1.
It uses compound keys. Mistake #2.
Given these domain classes:
Movie {
static hasMany = [ roles: Role ]
}
Person {
static hasMany = [ roles: Role ]
}
Role {
Movie movie
Person person
String foo
}
I want to move roles from one person to another, like so:
Role x = person1.roles[0]
x.person = person2
save(flush:true)
But nothing happens. At all. I've turned on trace and debug level logging for hibernate in log4j and it shows no update statement. But, if I do this:
Role x = person1.roles[0]
x.person = person2
x.foo = "i can haz update?"
save(flush:true)
An update does happen for foo, but the foreign key pointing to person is not modified, as shown by:
DEBUG hibernate.SQL - update ct_roles set foo=? where movie_id=? and person_id=?
TRACE sql.BasicBinder - binding parameter [1] as 'i can haz update?'
TRACE sql.BasicBinder - binding parameter [2] as [BIGINT] - 999
TRACE sql.BasicBinder - binding parameter [3] as [BIGINT] - 2
Note that person_id 2 belongs to person2, which as yet, has no roles, so the update fails.
So, short of simply deleting the old role and creating a new one attached to the desired person, is there any way to solve this?

Answer 1

Try:
person1.removeFromRoles(role) //role is the role object from which person is to be removed
role.person = person2
Should work.

Answer 2

The answer is:
class Role {
Movie movie
Person person
String fuGorm
def move(Person newbie) {
def m = this.movie?.id
def p = this.person?.id
def n = newbie?.id
// bypass GORM and issue a raw SQL update command...
def q = "update ct_roles set person_id=$n where person_id=$p and movie_id=$m"
def success = runCommand(q)
if (success) {
// the above bypasses GORM, so we should still
// perform the operation using GORM speak
// otherwise our objects will be out of sync with the DB.
// The following EPIC FAILS to update the DB,
// but it does update the local Grails domain objects
this.person.removeFromRoles(this)
this.person = newbie
newbie.addToRoles(this)
}
return success
}
def runCommand = { query ->
def db = new Sql(dataSource)
db.execute (query)
}
}