Spring and attach() method behaviour

General
1

Hello,

I’m new on Vaadin (6.8.8) and I’m trying to integrate Spring with Vaadin. I follow
this tutorial
 to get annotation integration and it seems that works.

But I noticed that in some classes when I call to constructor method the dependencies aren’t injected, but if I implement attach method the dependencies are injected.

Here is a class with this problem:


@Configurable
public class HotelAvailabilityPanel extends Panel {
	
	private static String NO_IMAGE_FILE = "images/no_image.png";

	@Autowired
	private AvailabilityController controller;
	
	private MessageHelper msg;
	private MainApplication app;

	private RoomStay roomStay;
	
	public HotelAvailabilityPanel(MainApplication app, RoomStay roomStay) {
		this.roomStay = roomStay;
		this.msg = app.getMsg();
		this.app = app;
		
		//init();
	}
	
        @Override
	public void attach() {
		init();
	}
	
	private void init() {
		
		// Layout with hotel information
		HorizontalLayout hotelInfoLayout = new HorizontalLayout();
		hotelInfoLayout.setMargin(false);
		hotelInfoLayout.setSpacing(true);
		hotelInfoLayout.setSizeFull();
		
		/**
                     ...
                     some code which calls to getBestPrice()
                     ...
                **/
	}
	
	private String getBestPrice() {
		return controller.getRoomRateBestPrice(roomStay).toString() + msg.getMessage("currency1");
	}
	
}

If I call init() method inside the constructor, the controller is null, but If I call init() method inside attach() method, the controller is not null.

I think I am missing something. Why is my depencency not injected in that case? What is the attach() method approach?

2

Your controller gets injected using Setter-based DI. So it can’t be set in the constructor as the Object needs to be constructed before the dependencies can be injected.

3

Thank you! Now it works.

4

For completeness sake, if you are using field autowiring, you can can also tell Spring to autowire the fields before construction by specifitying preConstruction=true on the Configurable annotation - i.e. @Configurable(preConstruction = true)

(See note in
Spring Documentation
)

Cheers,

Charles