Is it possible to change the querystring variable in ASP.NET MVC path before it hits the controller?

Question

I have a controller method in ASP.NET MVC that looks like this:

public ActionResult GetAlbumPictures(int albumId)
{
    var album = AlbumRepo.GetSingle(albumId);
    var pictures = album.Pictures;
    return View(pictures);
}

The routing for this method looks like this:

routes.MapRoute(null,
                "pictures"
                new { controller = "Album", action = "GetAlbumPictures" });

The user will use the following URL to get the pictures, filtered by the album ID:

GET http://server/pictures?albumid=10

However, I'd like to change the querystring parameter to just album instead of albumid:

GET http://server/pictures?album=10

This would mean that the controller method needs to be modified to:

public ActionResult GetPictures(int album)
{
    ...
}

However, this is not ideal because now the method has a parameter named album, which can be confused as an Album object instead of the ID of the Album.

My question is, is there any way of configuring ASP.NET MVC so that in the routing, it will receive a querystring parameter called album, but then pass it off to the controller as the albumId parameter?

P.S. I know that I can do this in the routing table:

routes.MapRoute(null,
                "album/{albumId}/pictures",
                new { controller = "Album", action = "GetAlbumPictures" });

But due to legacy issues, I have to make it work for the querystring method as well.

Scott · Accepted Answer · 2010-12-30 00:39:58Z

10

You can create a custom action filter attribute to handle this scenario. I haven't tested this specific implementation, but the general idea is to do something like this:

public class AlbumAttribute : ActionFilterAttribute
    {
         public override void OnActionExecuting(ActionExecutingContext filterContext)
         {
             var albumId = filterContext.HttpContext.Request.QueryString["album"] as string;
             filterContext.ActionParameters["albumId"] = albumId;

             base.OnActionExecuting(filterContext);
         }
    }

Then, decorate your action method with the [Album] attribute:

[Album]
public ActionResult GetAlbumPictures(int albumId)
{
    var album = AlbumRepo.GetSingle(albumId);
    var pictures = album.Pictures;
    return View(pictures);
}

edited Dec 30, 2010 at 0:39

answered Dec 30, 2010 at 0:20

Scott

14k20 gold badges99 silver badges156 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

ShahidAzim Over a year ago

It will not work, as Request.QueryString["album"] is not accessible within AlbumAttribute class.

Scott Over a year ago

Actually, yes it is. I've updated the code to reflect the correct way of accessing it.

Daniel T. Over a year ago

Thanks, this seems to be the most elegant solution.

Leon Over a year ago

I need to change the value of querystring before passing to all the actions. Where should I do it instead of adding an action filter attribute to each action?

Dio Phung Over a year ago

@Leon: you can change it in Controller OnActionExecuting(). Here is my code: pastebin.com/uYCmfvXr

ShahidAzim · Accepted Answer · 2010-12-30 01:07:58Z

1

You can use a Custom Model Binder and it will work with both album and albumId. It can be implemented as follows:

Custom Model Binder:

public class AlbumModelBinder : IModelBinder
{
    public object BindModel
    (ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        int albumId;
        var albumVar = bindingContext.ValueProvider.GetValue( "album" );
        if (albumVar != null)
        {
            albumId = int.Parse( albumVar.AttemptedValue );
        }
        else
        {
            albumId = int.Parse( bindingContext.ValueProvider.GetValue( "albumId" ).AttemptedValue );
        }
        return albumId;
    }
}

Action implementation:

public ActionResult GetAlbumPictures
([ModelBinder( typeof( AlbumModelBinder ) )] int albumId)
{
    var album = AlbumRepo.GetSingle(albumId);
    var pictures = album.Pictures;
    return View(pictures);
}

Global.asax.cs implementation:

protected void Application_Start()
{
    AreaRegistration.RegisterAllAreas();
    ModelBinders.Binders.Add( typeof( int ), new AlbumModelBinder() );
    RegisterRoutes( RouteTable.Routes );
}

edited Dec 30, 2010 at 1:07

answered Dec 30, 2010 at 0:56

ShahidAzim

1,5141 gold badge10 silver badges15 bronze badges

1 Comment

Daniel T. Over a year ago

Thanks for your answer. A custom model binder would work great, but for something trivial like this case, it's just a little more work than I'd like.

Pauli Østerø · Accepted Answer · 2010-12-30 03:02:06Z

1

Consider intercepting your request and use HttpContext.RewritePath to alter the query string before its picked up by the Routing engine. There is a nice diagram here showing how Url Rewriting is executed ages before the routing :)

http://learn.iis.net/page.aspx/496/iis-url-rewriting-and-aspnet-routing/

answered Dec 30, 2010 at 3:02

Pauli Østerø

6,9262 gold badges34 silver badges48 bronze badges

Comments

lukiffer · Accepted Answer · 2010-12-30 00:15:06Z

-1

You can intercept the request before it hits the controller in Application_BeginRequest in your global.asax. You won't have access to the MVC contexts though, but could use

Server.Transfer(...);

or

Response.Redirect(...); 
Response.End();

answered Dec 30, 2010 at 0:15

lukiffer

11.4k9 gold badges48 silver badges71 bronze badges

1 Comment

Pauli Østerø Over a year ago

why wouldn't you use HttpContext.RewritePath in a case like this? IMO its perfect for these kind of cases, no?

Collectives™ on Stack Overflow

Is it possible to change the querystring variable in ASP.NET MVC path before it hits the controller?

4 Answers 4

5 Comments

1 Comment

Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

5 Comments

1 Comment

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related