Question

I created a static scaffolding for my domain class and got a controller for that domain class. The create action of the controller looks like:

def create() {
    [userInstance: new User(params)]
}

I wonder why the line:

[userInstance: new User(params)]

has been added. Obviously when the create action is invoked, there wont be any params – so why would this line have been added?

Answer 1

Obviously when the create action is invoked, there wont be any params

Not necessarily – imagine a situation where you want to pre-populate a couple fields in the form of the create view. You could use:

/app/user/create?username=myusername

Which would result in the view’s userInstance having a populated username field for display in the form.