Grails save extend class - class

Question

how to save class extend in grails?
example i have class user and administrator
class User {
String name
String password
}
class Administrator extends User {
String authoritySelected
}
example in class User i have save "user1",
and then i want to change user1 from class user to class administrator and update authoritySelected
def update(){
def user1 = User.get("user1")
user1.authoritySelected
user1.save(flush:true)
}
and get error :
No such property: authoritySelected for class:User
so, how to save authoritySelected in class User and change that to class Administrator? thanks.

Answer 1

Speaking about the syntax, the code you wrote has no sense. Speaking about design, neither.
May I suggest you to study a bit a OOP before attempting doing this kind of stuff? :)
But let's face the problem you submitted.
First suggestion: don't implement the security system for your application, there's a lot of stuff that can do it for you. One above all: Spring Security plugin.
Second: the code you wrote doesn't work because extending a class is a way to make another class 'son' of the parent. In you example, Administrator is a son of User.
def update(){
def user1 = User.get("user1") // I don't get how this should work, but I'll leave it like this in this example
user1.authoritySelected // you're trying to GET the value a property that doesn't exist in the User class, you should SET something here
user1.save(flush:true)
}
If you want your User to change role, the easiest think is to think at the role not as another class, instead it should be an attribute of the User, so you can change it. Once the instance of a class is created, you can't change it (probably this is not totally true, but you shouldn't).
OK, some code:
class User {
String name
String password
String authority // a property of the class you can change
}
def update(){
def user1 = User.get("user1")
user1.authority = 'Administrator' // change the property on the instance you retrieved
user1.save() // save the instance itself
}
This is still not a good design solution to me, I'm just trying to make you able to see what you're doing wrong.

Answer 2

When you say "and then i want to change user1 from class user to class administrator", what exactly are you trying to do?
You are trying to access a property of an object that doesn't exist in that object. Downcasting simply doesn't work like that. You should instantiate an object of type Administrator in order to save one of its properties after.

Answer 3

if you want to create a USER you have to create an USER's instance, for example:
User u = new User(name: "xpto", password: "xptopass").save(flush:true)
An Administrator is a USER too, but with one more data, the authoritySelected, so if the Administrator extends User, he have the same data like a User too.
Administrator a = new Administrator(name: "xpto", password: "xptopPass", authoritySelected: "ADMIN").save(flush:true)
Attention, Object.get(X) methods needs an ID (Long), "X" would be a Long value, not a String.
http://grails.org/doc/2.3.x/ref/Domain%20Classes/get.html