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It's common to want the user to confirm his action if it would be hard to reverse, e.g. if he asked to delete something. The confirmation can be easily obtained via a javascript confirm dialog box. If you'd rather not use javascript, another approach is outlined below.

Using Javascript

Wicket 6.x

This is a solution from Sven Meier - 'overwrite #updateAjaxAttributes in your behavior or AjaxLink'. To make a reusable Component, simply create an abstract base class:

public abstract class ConfirmationLink<T> extends AjaxLink<T>
{
	private static final long serialVersionUID = 1L;
	private final String text;

	public ConfirmationLink( String id, String text )
	{
		super( id );
		this.text = text;
	}

	@Override
	protected void updateAjaxAttributes( AjaxRequestAttributes attributes )
	{
		super.updateAjaxAttributes( attributes );

		AjaxCallListener ajaxCallListener = new AjaxCallListener();
		ajaxCallListener.onPrecondition( "return confirm('" + text + "');" );
		attributes.getAjaxCallListeners().add( ajaxCallListener );
	}
}

Earlier Wicket versions

Here's one way to do thisget confirmation, using Javascript:

Link removeLink = new Link("removeLink") {
			@Override
			public void onClick() {
				// do something you want to confirm beforehand
			}
		};

removeLink.add( new SimpleAttributeModifier("onclick", "return confirm('are you sure?');"));

SimpleAttributeModifier will replace any existing onclick handler in the html. We can instead add our javascript to any existing javascript by attaching an IBehavior object to the Link. First we define a class that implements IBehaviorcreating our own AttributeModifier instead of using SimpleAttributeModifier:

public class JavascriptEventConfirmation extends AbstractBehaviorAttributeModifier {
	private final String msg;

	private final String event;

	public JavascriptEventConfirmation(String event, String msg) {
		this.msg = msg;
		this.event = event;
	super(event, new Model(msg));
	}

	@Override
	public void onComponentTag(Component component, ComponentTag tagprotected String newValue(final String currentValue, final String replacementValue) {
		String scriptprefix = (String) tag.getAttributes().get(event);
		script"var conf = "confirm('" + msgreplacementValue + "'); " + script
			"if (!conf) return false; ";
		String result = prefix;
		tag.put(event, script)if (currentValue != null) {
			result = prefix + currentValue;
		}
		return result;
	}
}

Then we add attach the behavior instead of an attribute modifiermodifier to the link:

	removeLink.add(new JavascriptEventConfirmation("onclick", "are you sure?"));

...

abstract public class ConfirmLink extends Link {
      public ConfirmLink(String id, String msg) {
           super(id);
           add(new JavascriptEventConfirmation("onclick", "are you sure?"));
      }

      @Override
      abstract public void onClick();
			
}

(The subclass could of course use SimpleAttributeModifier instead.)

Without Javascript

If you don't want to use javascript, you could bring up a separate web page with a confirmation form in it. But it's possible to display the confirmation request on the form page itself. The idea (due to Ed Eustace) is to use the wicket Component.replaceWith() method to replace some panel on the page with a confirmation panel.

First, here's the confirmation panel:

public abstract class ConfirmDeletePanel extends Panel {
     public ConfirmDeletePanel(String id, String message) {
         super(id);
	 add(new Label("message", message));
	 add(new Link("confirm") {
	      @Override
	      public void onClick() {
	        onConfirm();
	      }
	    });
	 add(new Link("cancel") {
	      @Override
	      public void onClick() {
	        onCancel();
	      }
	    });
     }
     protected abstract void onCancel();
     protected abstract void onConfirm();
}

(The corresponding html should be pretty obvious.)

Now assume the link to be confirmed is inside a panel called MyPanel. The link has a onClick method that does the panel replacement:

Link removeLink = new Link("removeLink") {
	@Override
	public void onClick() {
		MyPanel.this.replaceWith(new ConfirmDeletePanel(
				MyPanel.this.getId(), "are you sure") {

			@Override
			protected void onCancel() {
				this.replaceWith(MyPanel.this);
			}

			@Override
			protected void onConfirm() {
				// do something you want confirmed beforehand
				// .... then
				this.replaceWith(MyPanel.this);
			}
		});
	}

};