Render a Wicket page to a string for HTML email

Something that’s very desirable to do in Apache Wicket is create HTML emails using Wicket’s brilliant component-oriented markup.

I’ve been working on this problem on and off for ages — it’s tricky because of teh way that markup rendering is so deeply tied to the requestcycle, which in turn is deeply dependent on the httpservletrequest — with good reason, too. That’s where Wicket gets its autoconfiguring magic from!

So in order to use Wicket to create HTML emails, we need to fake the request/response cycle. I wrote this convenient method that renders a bookmarkable page (pageclass + pageparameters) to a string:

protected String renderPage(Class<? extends Page> pageClass, PageParameters pageParameters) {

		//get the servlet context
		WebApplication application = (WebApplication) WebApplication.get();

		ServletContext context = application.getServletContext();

		//fake a request/response cycle
		MockHttpSession servletSession = new MockHttpSession(context);
		servletSession.setTemporary(true);

		MockHttpServletRequest servletRequest = new MockHttpServletRequest(
				application, servletSession, context);
		MockHttpServletResponse servletResponse = new MockHttpServletResponse(
				servletRequest);

		//initialize request and response
		servletRequest.initialize();
		servletResponse.initialize();

		WebRequest webRequest = new WebRequest(servletRequest);

		BufferedWebResponse webResponse = new BufferedWebResponse(servletResponse);
		webResponse.setAjax(true);

		WebRequestCycle requestCycle = new WebRequestCycle(
				application, webRequest, webResponse);

		requestCycle.setRequestTarget(new BookmarkablePageRequestTarget(pageClass, pageParameters));

		try {
			requestCycle.request();

			log.warn("Response after request: "+webResponse.toString());

			if (requestCycle.wasHandled() == false) {
				requestCycle.setRequestTarget(new WebErrorCodeResponseTarget(
						HttpServletResponse.SC_NOT_FOUND));
			}
			requestCycle.detach();

		} finally {
			requestCycle.getResponse().close();
		}

		return webResponse.toString();
	}

One other thing that’s desirable to do is change all relative links in the email to absolute URLs — something that Wicket makes super-easy, if you know how. That will be the subject of my next post.

Tags: apache, email, html, java, Programming, wicket