mvp4g LazyPresenter with option multiple=true is binded twice

Question

I am using mvp4g in my gwt project. For one of my presenters I am using option multiple=true and I am creating and binding presenters in that way:

ObjectPresenter mainObject = eventBus.addHandler(ObjectPresenter.class, false);
mainObject.setId(id);
mainObject.bind();
view.addWidget(mainObject.getView().asWidget());

ObjectPresenter extends LazyPresenter.

When I am calling first event from the eventBus that is caught by ObjectPresenter, method bind() of the LazyPresenter is called again.

bind method has inside tree other methods: createPresenter(); view.createView(); bindView();. In the bindView method of the ObjectPresenter I am modifing my view by adding next widgets. Because the method is called twice (once directly by me, and once by framework) some widgets are duplicated.

I've debugged the code and I found that this part of code from BaseEventHandler is called when the event from the eventBus is called:

public final boolean isActivated( boolean passive, String eventName, Object... parameters ) {
    boolean activated = this.activated && pass( eventName, parameters );
    if ( activated ) {
        if ( passive ) {
            return binded;
        } else {
            onBeforeEvent();
            if ( !binded ) {
                bind();
                binded = true;
            }
        }
    }
    return activated;
}

After calling bind directly (by mainObject.bind()) binded property in the BaseEventHandler is not set to true, so bind method is called again when first event is called.

I can set binded variable from the BaseEventHandler to true in the ObjectPresenter when the method bind (called directly) is finished, but I am not sure if it is proper approach...

Could you please give me a hint how to deal with this issue?

Thanks for your help.

Answer 1

I haven't read documentation carefully enough! I was using method eventBus.addHandler(ObjectPresenter.class, false) (with bind parameter), which has following java doc.

     /**
     * Create a new instance of the handler, bind it only if this option is set to true and add it
     * to event bus. If you decide not to bind the handler at creation, you will have either make
     * sure the handler is displayed only after it handles its first method (otherwise the view is
     * not binded so it seems inactive) or call manualy the bind method.<br/>
     * <br/>
     * When binding the handler, you have to call the isActivated method. This method will be called
     * with eventName and parameters set to null.
     * 
     * @param <T>
     *            type of the handler created
     * @param handlerClass
     *            class of the handler to create
     * @param bind
     *            if true, bind the handler at creation, otherwise do nothing.
     * @return new instance of the handler created
     * 
     * @throws Mvp4gException
     *             thrown if the instance of the handler can not be created by the event bus
     */
    <E extends EventBus, T extends EventHandlerInterface<E>> T addHandler( Class<T> handlerClass, boolean bind ) throws Mvp4gException;

The part I missed is When binding the handler, you have to call the isActivated method. This method will be called with eventName and parameters set to null. and that was my problem - I didn't do this!