Error Pages

How do I add custom error pages?

Non-HTTP Error Pages

In your application class that extends WebApplication, set the following in the init() method:

getApplicationSettings().setPageExpiredErrorPage(MyExpiredPage.class);
getApplicationSettings().setAccessDeniedPage(MyAccessDeniedPage.class);
getApplicationSettings().setInternalErrorPage(MyInternalErrorPage.class);

There are also some other neat settings you should check out in getApplicationSettings(), getDebugSettings(), getExceptionSettings(), getMarkupSettings(), getPageSettings(), getRequestCycleSettings(), getSecuritySettings and getSessionSettings(). See the javadoc for more information.

If calling setInternalErrorPage, make sure to also call:

// show internal error page rather than default developer page
getExceptionSettings().setUnexpectedExceptionDisplay(IExceptionSettings.SHOW_INTERNAL_ERROR_PAGE);

You can also add customized error per page. In your WebPage class:

getRequestCycle().onRuntimeException(new MyErrorPage(), theException);

HTTP Error Pages

First ensure that the wicket filter-mapping in your web.xml has the following dispatchers:

	<filter-mapping>
		<filter-name>WicketFilter</filter-name>
		<url-pattern>/*</url-pattern>
		<dispatcher>REQUEST</dispatcher>
		<dispatcher>ERROR</dispatcher>
	</filter-mapping>

	<error-page>
		<error-code>404</error-code>
		<location>/404</location>
	</error-page>

This is assuming that you have mapped "/404" in your WebApplication:

	mount(new HybridUrlCodingStrategy("/404", PageNotFound.class));

In your error WebPage:

public class PageNotFound extends WebPage {

	private static final long serialVersionUID = 1L;

	public PageNotFound() {
		// Add any necessary components
	}

	@Override
	protected void configureResponse() {
		super.configureResponse();
		getWebRequestCycle().getWebResponse().getHttpServletResponse().setStatus(HttpServletResponse.SC_NOT_FOUND);
	}

	@Override
	public boolean isVersioned() {
		return false;
	}

	@Override
	public boolean isErrorPage() {
		return true;
	}

}

How do I add/display errors?

Normally all that is needed to display errors in a page is to call the "error" method in the WebPage:

error("Message to the user indicating that an error occurred");

// alternative to get the message from a .properties file: error.login.user.invalid=${username} is not a valid user
error(new StringResourceModel("error.login.user.invalid", this, myUserModelThatHasAUsernameProperty).getString());

If an error occurred where the user needs to be directed to a different page we need to set the error on the session:

getSession().error(message);
throw new RestartResponseException(MyErrorPage.class, optionalPageParameters);
// use RestartResponseAtInterceptPageException(MyErrorPage.class);
// instead to interrupt current request processing and immediately redirect to an intercept page

// it may be tempting to do the following, but it should not be done:
// error(message);
// setResponsePage(MyErrorPage.class);

To display an error (or any message for that matter: info/warning) in an HTML page use a FeedbackPanel:

<!-- In the HTML page -->
<div wicket:id="feedback">[Feedback Panel]</div>

// In WebPage
add(new FeedbackPanel("feedback"));

How do I add/display errors at the component level?

See ComponentFeedbackPanel

// TODO : add example that adds error messages to individual form components of the page

I get 'Internal error cloning object' errors

This is a debug feature to help find potential problems when the application runs clustered. It checks the component graphs to make sure everything is serializable (which is required for clustering).

If clustering support is not needed, these checks can be disabled by doing getDebugSettings().setSerializeSessionAttributes(false); in the application.init()

Also, if the configuration parameter in the web.xml is set to DEPLOYMENT, these checks are disabled.

Answer provided courtesy Igor Vaynberg

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