Question

I created an HtmlHelper extension call ActionButton which will spit out a jQuery button that will call an action rather than using ActionLink. However, I receive an exception from within my extension method on the following line (it’s just a sample of code that will raise the exception I was seeing):

    MvcHtmlString str = helper.Action(actionName, controllerName, routeValues);

Here’s the full method but using UrlHelper to create the Action URL (which works for me). I also have using System.Web.Mvc and using System.Web.Mvc.Html.

    public static HtmlString ActionButton(this HtmlHelper helper, string linkText, string actionName, string controllerName, object routeValues)
    {
        TagBuilder tag = new TagBuilder("a");
        UrlHelper urlHelper = new UrlHelper(helper.ViewContext.RequestContext);
        tag.MergeAttribute("href", urlHelper.Action(actionName, controllerName, routeValues));

        // the next line causes the exception, not really being used other than to 
        // raise the exception and illustrate the call I was making
        MvcHtmlString str = helper.Action(actionName, controllerName, routeValues);

        tag.MergeAttribute("rel", "external");
        tag.MergeAttribute("data-role", "button");
        tag.MergeAttribute("data-mini", "true");
        tag.MergeAttribute("data-inline", "true");
        tag.MergeAttribute("data-icon", "arrow-r");
        tag.MergeAttribute("data-iconpos", "right");
        tag.MergeAttribute("data-theme", "b");

        tag.SetInnerText(linkText);
        HtmlString html = new HtmlString(tag.ToString(TagRenderMode.Normal));
        return html;
    }

I would like to know why calling helper.Action(...) raises an exception.

Thanks!

Answer 1

HtmlHelper.Action() will call the action method you pass it immediately, and return its results.
That’s not what you want.

You want UrlHelper.Action(), which returns a URL to the action.