Q:

Grails "not-null property references a null or transient value" exception on web flow

I'm getting "org.springframework.dao.DataIntegrityViolationException: not-null property references a null or transient value: A.b" exception on web flow in grails 1.1.2.
there is 
class B {
   ...
   static belongsTo = [a:A]
   ...
}

and 
class A {
   ...
   static hasMany = [b:B]
   ...
}

Does anyone know what is wrong?
Thanks
Tom

A:

Solved.
There was a different problem. I wasn't persisting anything. There appeared some inconsistences between serialized data in the flow and persisted data in the database. So a select query caused this exception.

