ASP.NET MVC `Html.ActionLink` between "Areas"

Question

I have added a new Area to my MVC3 project and I am trying to link from the _Layout page to the new Area. I have added an Area called 'Admin' that has a controller 'Meets'.

I used the visual studio designer to add the area so it has the correct area registration class etc, and the global.asax file is registering all areas.

However, when I use the following 2 action links in a page in the root, I run into a few problems:

@Html.ActionLink("Admin", "Index", "Meets", new { area = "Admin" }, null)
@Html.ActionLink("Admin", "Index", "Meets", new { area = "" }, null)

When clicking both links, I am taken to the Meets controller in the Admin area, where the application then proceeds to throw an error saying it cannot find the Index page (even though the Index page is present in the Views folder in the Area sub-directory.

The href for the 1st link looks like this:

http://localhost/BCC/Meets?area=Admin

And the href for the 2nd link looks like this:

http://localhost/BCC/Meets

Also if I hit the link that I expect to be created:

http://localhost/BCC/Admin/Meets

I just get a resource cannot be found error. All very perplexing! I hope someone can help...

Solution 1

I figured this out - I created a new test project and did exactly the same thing I was doing before and it worked...then after further inspection of all things route-related between the two projects I found a discrepancy.

In the global.asax file in my BCC application, there was a rogue line of code which had inexplicably appeared:

        public static void RegisterRoutes(RouteCollection routes)
        {
            // Problem here
            routes.Clear();

            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

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

        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();

            RegisterGlobalFilters(GlobalFilters.Filters);
            RegisterRoutes(RouteTable.Routes);
        }

As you can see where my comment is, at some time or other I had placed the routes.Clear() call at the beginning of RegisterRoutes, which meant after I had registered the Areas in Application_Start, I was then immediately clearing what I had just registered.

Thanks for the help...it did ultimately lead to my salvation!

Solution 2

Strange indeed. Steps that worked perfectly fine for me:

1. Create a new ASP.NET MVC 3 application using the default Visual Studio template
2. Add an area called Admin using Visual Studio designer by right clicking on the project

3. Add new Controller in ~/Areas/Admin/Controllers/MeetsController:

   public class MeetsController : Controller
   {
       public ActionResult Index()
       {
           return View();
       }
   }
   

4. Add a corresponding view ~/Areas/Admin/Views/Meets/Index.cshtml

5. In the layout (~/Views/Shared/_Layout.cshtml) add links:

   @Html.ActionLink("Admin", "Index", "Meets", new { area = "Admin" }, null)
   @Html.ActionLink("Admin", "Index", "Meets", new { area = "" }, null)
   

6. Run the application.

Rendered HTML for the anchors:

<a href="/Admin/Meets">Admin</a>
<a href="/Meets">Admin</a>

As expected the first link works whereas the second doesn't.

So what's the difference with your setup?

Solution 3

Another option is to utilize RouteLink() instead of ActionLink(), which bypasses the area registrations altogether:

ActionLink version:

Html.ActionLink("Log Off", "LogOff", "Account", new { area = "" }, null)

RouteLink version:

Html.RouteLink("Log Off", "Default", 
    new { action = "LogOff", controller = "Account" })

The second parameter is a "Route Name" which is registered in Global.asax.cs and in various 'AreaRegistration' subclasses. To use 'RouteLink' to link between different areas, you only need to specify the correct route name.

This following example shows how I would generate three links to different areas from a shared partial, which works correctly regardless of which area I am 'in' (if any):

@Html.RouteLink("Blog", "Blog_default", 
    new { action = "Index", controller = "Article" })
<br/>
@Html.RouteLink("Downloads", "Download_default", 
    new { action = "Index", controller = "Download" })
<br/>
@Html.RouteLink("About", "Default", 
    new { action = "Index", controller = "About" })

Happy coding!

Solution 4

Verify that your AdminAreaRegistration class looks like this:

public class AdminAreaRegistration : AreaRegistration
{
    public override string AreaName
    {
        get
        {
            return "Admin";
        }
    }

    public override void RegisterArea(AreaRegistrationContext context)
    {
        context.MapRoute(
            "Admin_default",
            "Admin/{controller}/{action}/{id}",
            new { action = "Index", id = UrlParameter.Optional }
        );
    }
}

and that you have this in Global.asax.cs:

protected void Application_Start()
{
    ... // ViewEngine Registration
    AreaRegistration.RegisterAllAreas();
    ... // Other route registration
}

Solution 5

I solved this problem by doing the following.

In my Global.asax.cs, I have

    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        filters.Add(new HandleErrorAttribute());
    }

    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
        routes.IgnoreRoute("{*favicon}", new { favicon = @"(.*/)?favicon.ico(/.*)?" });
    }

    protected void Application_Start()
    {
        //Initialise IoC
        IoC.Initialise();

        AreaRegistration.RegisterAllAreas();
        RegisterGlobalFilters(GlobalFilters.Filters);
        RegisterRoutes(RouteTable.Routes);
    }

In my PublicAreaRegistration.cs (Public Area), I've got

public class PublicAreaRegistration : AreaRegistration
{
    public override string AreaName
    {
        get
        {
            return "Public";
        }
    }

    public override void RegisterArea(AreaRegistrationContext context)
    {
        context.MapRoute("Root", "", new { controller = "Home", action = "Index" });

        context.MapRoute(
            "Public_default",
            "Public/{controller}/{action}/{id}",
            new { controller = "Home", action = "Index", id = UrlParameter.Optional }
            , new[] { "<Project Namespace here>.Areas.Public.Controllers" }
        );
    }
}

In my AuthAreaRegistration.cs (Area for Restricted access), I've got

public class AuthAreaRegistration : AreaRegistration
{
    public override string AreaName
    {
        get
        {
            return "Auth";
        }
    }

    public override void RegisterArea(AreaRegistrationContext context)
    {
        context.MapRoute(
            "Auth_default",
            "Auth/{controller}/{action}/{id}",
            new { controller = "Home", action = "Index", id = UrlParameter.Optional }
        );
    }
}

And finally, my links in my *.cshtml pages would be like

1) @Html.ActionLink("Log Off", "LogOff", new{area= "Public", controller="Home"})

or

2) @Html.ActionLink("Admin Area", "Index", new {area= "Auth", controller="Home"})

Hope this saves someone hours of research! BTW, I'm talking about MVC3 here.

Kwex.

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Comments

[Shaun Wilson]

A note to readers, the ActionLink examples here would result in the same problem the OP was experiencing, despite the other changes, they should be written as follows: 1) @Html.ActionLink("Log Off", "LogOff", new{area= "Public", controller="Home"}, null) or 2) @Html.ActionLink("Admin Area", "Index", new {area= "Auth", controller="Home"}, null)

[Shaun Wilson]

There is no "Admin" controller for area "", in your case you created a new "Admin" area with a 'MeetsController' and so the first link should work as intended. If you truly want the controller from the "Admin" area to execute 'anywhere' you can try moving all the views, partials, etc out of the 'Admin' area and into the root of your web app. I'm not sure how well (if) this would work.