I have a Profile model with a hasOne relationship to a Detail model. I have a registration form that saves data into both model's tables, but I want the username field from the profile model to be copied over to the
usernamefield in the details model so that each has the same username.

function new_account()
{
    if(!empty($this->data))
    {
        $this->Profile->modified = date("Y-m-d H:i:s");                 
        if($this->Profile->save($this->data))
        {
            $this->data['Detail']['profile_id'] = $this->Profile->id;
            $this->data['Detail']['username'] = $this->Profile->username;

        $this->Profile->Detail->save($this->data);
        $this->Session->setFlash('Your registration was successful.');

                    $this->redirect(array('action'=>'index'));
        }
    }

}

This code in my Profile controller gives me the error:

Undefined property: Profile::$username

Any ideas?