Question

In my layout page, the links to the main sections that make up my site are rendered with a call like this:

@SiteSectionLink("index", "blog", "blog")

Where SiteSectionLink is a helper that looks like this:

@helper SiteSectionLink(string action, string controller, string display)
  {
  <li>
    <h1>
      <a class="site-section" href="@Url.Action(action, controller)">@display</a></h1>
  </li>
}

On the actual blog page, all links also refer to the “Index” action but also specify either a date parameter (such as “blog/4-2011” or “blog/2010”) that is used to filter the posts by a date period. In addition to that, there’s also an optional postID parameter that is used to refer to a specific post.

To accomplish that, I have the following routes:

routes.MapRoute(
 "Blog", 
 "blog/{date}/{postID}", 
  new 
  { 
    controller = "blog", 
    action = "index", 
    date = UrlParameter.Optional, 
    postID = UrlParameter.Optional 
  } 
);

routes.MapRoute(
  "Default", // Route name
   "{controller}/{action}/{id}", // URL with parameters
    new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
);

Now, the problem is that when I have clicked a link that is something like “blog/11-2010” or “blog/11-2010/253” then the link in my layout page that refers to my blog in general now also refers to that same URL when I want it to just link to “blog/”, not “blog/11-2010”.

If I change the SiteSectionLink helper to explicitly pass in null for date and postID like this:

<a class="site-section" href="@Url.Action(action, controller, 
  new { date = (string)null, postID = (int?)null})">@display</a></h1>

The current route values are still used but now it looks like “blog?date=11-2010”.

I saw this similar question but the accepted answer doesn’t work for me, and I don’t use ActionLink in the first place and I suspect that ActionLink would use Url.Action under the hood.

Answer 1

While the issue you are experiencing is not quite the behavior detailed by Phil Haack in this blog post regarding a bug with MVC3 routing and a route with two optional parameters, I would suggest applying the fix described in Phil’s post.

I also would suggest never creating a route with two optional parameters, and instead follow the pattern of breaking the desired routing into two separate routes.