Controller Action Methods with different signature

问题:

I am trying to get my URLs in files/id format. I am guessing I should have two Index methods in my controller, one with a parameter and one with not. But I get this error message in browser below.

Anyway here is my controller methods:

public ActionResult Index()
{
    return Content("Index ");
}

public ActionResult Index(int id)
{
    File file = fileRepository.GetFile(id);
    if (file == null) return Content("Not Found");
    else return Content(file.FileID.ToString());
}

Update: Done with adding a route. Thanks to Jeff

回答1:

You can only overload Actions if they differ in arguments and in Verb, not just arguments. In your case you'll want to have one action with a nullable ID parameter like so:

public ActionResult Index(int? id){ 
    if( id.HasValue ){
        File file = fileRepository.GetFile(id.Value);
        if (file == null) return Content("Not Found");
            return Content(file.FileID.ToString());

    } else {
        return Content("Index ");
    }
}

You should also read Phil Haack's How a Method Becomes an Action.

回答2:

To use the files/id URL format, remove the parameterless Index overload, and add this custom route first so it's evaluated before the default route:

routes.MapRoute(
        "Files",
        "Files/{id}",
        new { controller = "Files", action = "Index" }      
    );

See ASP.NET MVC Routing Overview for the basics of mapping URLs to controller methods and ScottGu's excellent URL Routing article, which has several examples very close to what you want to do.