net.java.html.json

Annotation Type Function

@Target(value=METHOD)
@Retention(value=SOURCE)
public @interface Function

Methods in class annotated by Model can be annotated by this annotation to signal that they should be available as functions to users of the model classes. The method should be non-private, static and return void. It may take few arguments. The first argument can be the type of the associated model class, the other argument can be of any type, but has to be named data - this one represents the actual data the function was invoked on. Example:

 
 @Model(className="Names", properties={
   @Property(name = "selectedName", type=String.class),
   @Property(name = "names", type=String.class, array = true)
 })
 static class NamesModel {
   @Function static void nameSelected(Names myModel, String data) {
     myModel.setSelectedName(data);
   }
 
   static void initialize() {
     Names pageModel = new Names("---", "Jarda", "Pepa", "Honza", "Jirka", "Tomáš");
     pageModel.applyBindings();
   }
 }
 
 // associated Knockout HTML page:
 
 Selected name: <span data-bind="text: selectedName"></span>
 <ul data-bind="foreach: names">
   <li>
     <a data-bind="text: $data, click: $root.nameSelected" href="#"></a>
   </li>
 </ul> 
 

The above example would render: Selected name: ---

• Jarda
• Pepa
• Honza
• Jirka
• Tomáš

and after clicking on one of the names the --- would be replaced by selected name. Try this sample on-line!

There can be additional arguments in the method which can extract information from (typically event object) sent as a second parameter of the function dispatch method. Such arguments can be of primitive types (int, double or String). Their names are used to extract values of appropriate properties from the event object. The following function...

 @Function static void meaningOfWorld(Names myModel, String data, int answer) {
   System.out.println(answer);
 }
 // would print 42 if the dispatch method:
 meaningOfWorld.call(model, json)
 

is called with equivalent of var json = { 'answer' : 42 }.

Author:

Jaroslav Tulach