Persist Grails Domains *ONLY* after Relationship built

Question

I'm wondering if its possible to create a grails domain object, but only have it persist on command as opposed as when we do operations on it.

To be more precise, this is what I have to do now:

Foo foo = new Foo(name:"asdf")
Bar bar = new Bar(name:"gzxj")
bar.save() // persist here 
foo.save() // persist here
foo.addToBars(bar) //  now I have to build the relationship

What I want:

Foo foo = new Foo(name:"asdf")
Bar bar = new Bar(name:"gzxj")
foo.addToBars(bar) //  just build the relationship
bar.save() // would be great to ignore this step
foo.save() // can I now atomically build both objects and create the relationships? 

My impressions is that the latter would be far faster if there are many relationships to associate. Am I really just wanting NoSQL here?

Answer 1

Depending on how you have your relationships set up, this is entirely possible. It really has nothing to do with what database you have implemented.

Parent class

class Foo {
    String name

    static hasMany = [bars: Bar]
}

Child class

class Bar { 
    String name

    Foo foo //optional back reference       
    static belongsTo = Foo
}

Execution

Foo foo = new Foo(name: 'a')
Bar bar = new Bar(name: 'b')
foo.addToBars(bar)
foo.save()

//or even more terse

Foo foo = new Foo(name: 'c')
foo.addToBars(new Bar(name: 'd'))
foo.save()

The key is the belongsTo which defaults to a cascade of all. This can be explicitly set as well:

class Foo {
    String name

    static hasMany = [bars: Bar]

    static mapping = {
        bars cascade: 'all'
    }
}