DD4TFormRouteHandler (posting a form as tridion page url)

ASP.NET routing enables us to use URLs that are not physical files, In DD4T we have the default page route definition. In which all page request redirct to Page controller and process the page.

DD4TFormRouteHandler is a custom route handler responsible for mapping incoming browser requests to particular MVC controller actions, this works along with DD4TFormHelper (that generate the route information for the form)

Posting a form in DD4T is not complicated, you can create the mvc form as a normal controller and action, then post it via AJAX. But, when we need to do post the form as normal page, It would need a tweak as the controller/action is not a page existed in tridion. This can be achieved by implementing a custom Mvc RoutHandler and reroute the posted form to the encrypted action and controller. It works as below daigram.

So, how to do this. to render out the form we have BeginDD4TForm html helper as below that generate the form with encrypted route values.

@using (Html.BeginDD4TForm("Post", "Contact", FormMethod.Post))
{ 
    @Html.TextBox("username")
    <input type="submit" name="submit" value="Submit" />
}

BeginDD4TForm is a helper in the custom class DD4TFormHelper, which is responsible for generating encrypted route information.
Once this is done, then we need to add the custom handler to read the route information and route to the proper controller and action instead of the tridion page, this is the responsibilty of the class DD4TFormRouteHandler. To use this add this handler in your default page router as below.

  //Tridion page route
            routes.MapRoute(
               "TridionPage",
               "{*PageId}",
               new { controller = "Page", action = "Page" }, // Parameter defaults
               new { pageId = @"^(.*)?$" } // Parameter constraints
            ).RouteHandler = new DD4TFormRouteHandler();

This is the important step (Register the custom route handler)

In the action of form, once form is posted redirect to the current URL, so that it will load the Tridion page once the form is posted.

Both the helper and RouteHandler source code is below.

DD4TFormRouteHandler.cs
DD4TFormHelper.cs