AjaxHelperExtensions.cs

public static class AjaxHelperExtensions
{
		private static string GetLanguage()
		{
			if (HttpContext.Current == null || HttpContext.Current.Request.RequestContext == null)
				return null;

			return RequestContextExtension.GetLanguage(HttpContext.Current.Request.RequestContext);
		}

		private static MvcForm CreateAsyncForm(this AjaxHelper ajaxHelper, XFormParameters parameters, XForm xForm, AjaxOptions options)
		{
			RouteValueDictionary dictionary = new RouteValueDictionary(new
			{
				XFormId = xForm.Id,
				action = parameters.PostAction,
				controller = (parameters.PostController ?? string.Empty),
				failedAction = parameters.FailedAction,
				successAction = parameters.SuccessAction,
				language = GetLanguage(),
				contentLink = (parameters.ContentLink ?? string.Empty)
			});
			
			return ajaxHelper.BeginForm(parameters.PostAction, dictionary, options);
		}

		public static MvcForm BeginXForm(this AjaxHelper ajaxHelper, XForm xForm, AjaxOptions options)
		{
			if (xForm == null)
				return (MvcForm)null;

			XFormParameters parameters = XFormParameters.GetParameters((IDictionary<string, object>)ajaxHelper.ViewData);

			MvcForm form = CreateAsyncForm(ajaxHelper, parameters, xForm, options);

			if (ajaxHelper.ViewContext.ClientValidationEnabled)
			{
				ValidationRuleDescriptorCollection clientValidationRules = XFormClientValidationHelper.CreateClientValidationRules(xForm, LocalizationService.Current);
				MvcFormExtensions.AddClientValidationRules(form, ajaxHelper.ViewContext.FormContext, (IEnumerable<ValidationRuleDescriptor>)clientValidationRules);
			}

			return form;
		}
	}