grails-domain-id 无生成策略，由程序控制

class Menu implements Comparable<Menu>{
   String id;
   String name;  
}
static constraints = {
    //1
    id bindable : true
    name nullable:true
}
static mapping = {
    //2
    id column:‘MENU_ID‘ , generator:‘assigned‘
    name column:‘MENU_NAME‘ 
}

// 1
@Transactional
def test(){
     def m_lv1_i1 = new Menu(
                    name: ‘home‘,
                    id: "m_lv1_i1"
            ).save flush: true
}