ZK Developer's Reference/MVVM/ViewModel/Initialization

This article is out of date, please refer to zk-mvvm-book/8.0/viewmodel/initialization for more up to date information.

Initial Method

The binder is responsible for creating and initializing a ViewModel instance. If you want to perform your own initialization in a ViewModel, you can declare your own initial method by annotating a method with @Init. The Binder will invoke this method when initializing a ViewModel during a page creation phase. Each ViewModel can only have one initial method.

public class MyViewModel {

	@Init
	public void init(){
		//initialization code
	}
}

This annotation has an attribute named "superclass", if you set it to "true". The binder will look for the initial method of ViewModel's parent class and invoke it first if it exists.

public class ParentViewModel{

	@Init
	public void parentInit(){
		//initialization code
	}
}


public class ChildViewModel extends ParentViewModel{

	@Init(superclass=true)
	public void childInit(){
		//initialization code
	}
}

• Line 12: ParentViewModel's initial method is invoked first then ChildViewModel's.

Please notice that child class's initial method should not override parent class's initial method, or parent's initial method won't be called and child's will be called twice.

Apply on Class

 Since 6.0.1

If super has an init methold but its ChildViewModel doesn't, you can add @Init(superclass=true) on the ChildViewModel to use super's init.

public class ParentViewModel {
    @Init
    public void init(){}
}

@Init(superclass=true)
public class ChildViewModel extends ParentViewModel{
}

The initial method can retrieve various context object by applying annotation on its parameter, please refer ZK Developer's Reference/MVVM/Advance/Parameters.

Version History

Version	Date	Content
6.0.0	February 2012	The MVVM was introduced.