Mixin to allow any element to submit a form and trigger an event

I modified the builtin LinkSubmit component to be able to use the same thing on any element.

I changed it to a mixin and did some other minor changes.

@MixinAfter
@IncludeJavaScriptLibrary("AnySubmit.js")
public class AnySubmit {

  /**
   * The name of the event that will be triggered if this component is the cause of the form submission. The default
   * is "selected".
   */
  @Parameter(allowNull = false, defaultPrefix = BindingConstants.LITERAL)
  private String event = EventConstants.SELECTED;

  @Parameter(defaultPrefix = BindingConstants.LITERAL)
  private String clientEvent = "change";

  /**
   * The value that will be made available to event handler method of this component when the form is
   * submitted.
   */
  @Parameter
  private Object context;

  /**
   * If true (the default), then any notification sent by the component will be deferred until the end of the form
   * submission (this is usually desirable).
   */
  @Parameter
  private boolean defer = true;

  @InjectContainer
  private ClientElement container;

  @Inject
  private ComponentResources resources;

  @Inject
  private RenderSupport renderSupport;

  @Environmental
  private FormSupport formSupport;

  @Environmental
  private Heartbeat heartbeat;

  @Inject
  private Request request;

  @SuppressWarnings("serial")
  private static class ProcessSubmission implements ComponentAction {

    private final String clientId;

    public ProcessSubmission(String clientId) {
      this.clientId = clientId;
    }

    public void execute(AnySubmit component) {
      component.processSubmission(clientId);
    }
  }

  private void processSubmission(String clientId) {

    String hiddenFieldName = clientId + ":hidden";

    if (request.getParameter(hiddenFieldName) != null) {
      final Object[] contextToPublish = getContext(request, clientId);
      Runnable notification = new Runnable() {

        public void run() {
          resources.triggerEvent(event, contextToPublish, null);
        }
      };

      if (defer)
        formSupport.defer(notification);
      else
        heartbeat.defer(notification);
    }
  }

  private Object[] getContext(Request request, String clientId) {
    String contextFieldName = clientId + ":context";
    String context = request.getParameter(contextFieldName);
    if (context != null) {
      return new Object[] { context };
    }
    String value = request.getParameter(clientId);
    if (value != null) {
      return new Object[] { value };
    }
    return null;
  }

  void beginRender() {
    formSupport.store(this, new ProcessSubmission(container.getClientId()));
  }

  void afterRender(MarkupWriter writer) {
    renderSupport.addInit("anySubmit", formSupport.getClientId(), container.getClientId(), clientEvent);
    if (context != null) {
      writer.element("input", "type", "hidden", "value", context, "name", container.getClientId() + ":context");
      writer.end();
    }
  }
}






Tapestry.AnySubmit = Class.create({

    initialize: function(formId, clientId, event)
    {
        this.form = $(formId);
        this.element = $(clientId);

        this.element.observe(event, this.onEvent.bindAsEventListener(this));
    },

    createHidden : function()
    {
        var hidden = new Element("input", { "type":"hidden",
            "name": this.element.id + ":hidden",
            "value": this.element.id});

        this.element.insert({after:hidden});
    },

    onEvent : function(event)
    {
        Event.stop(event);

        var onsubmit = this.form.onsubmit;

        if (onsubmit == undefined || onsubmit.call(window.document, event))
        {
            this.createHidden();
            this.form.submit();
        }

        return false;
    }
});

Tapestry.Initializer.anySubmit = function(formId, clientId, event)
{
    new Tapestry.AnySubmit(formId, clientId, event);
}