Grails save() doesn't save if called after relationship is added

Question

I have two domain classes - Person has many Books. If I create a Person, call save(), then create+add Books to the Person, everything is persisted to the database. If I create a Person, then create+add Books, followed by save(), nothing get persisted.

Example code:

class Person {
   ...
   static hasMany = [books: Book]
}

class Book {
   ...
   static belongsTo = [person: Person]
}

Works, saves to database:

def person = new Person(...).save()
def book = new Book(...)
person.addToBooks(book)

Doesn't not work, doesn't save to database:

def person = new Person(...)
def book = new Book(...)
person.addToBooks(book)
person.save()

Why is this?

I'm running this from the Groovy console. I've tried calling ctx.sessionFactory.currentSession.clear() which doesn't help.

Resolved: The Book I was attaching to the Person had errors in it. By calling person.hasErrors() and getErrors() I was able to see that my Book was failing validation. This was being run from the Grails console so there wasn't any validation error messages.

Answer 1

I don't know for sure but I presume it's because save() sets the ID of the Person which would be required to be able to add a Book to it's book collection.

I'd suggest doing some googling on Hibernate collection behaviour, it could be the way Hibernate works or maybe it's a bug in the version of Grails you're using.

Another thing to try is forcing a flush with person.save(flush:true)

Answer 2

You need to manually flush the hibernate session like this:

person.save(flush:true)