URL.Action includes id when constructing URL

Question

I'm using ASP.Net MVC. Here's my code snippets from a controller named Course:

public ActionResult List(int id)
{
    var viewmodel.ShowUrl = Url.Action("Show", "Course");


    ...
}

public ActionResult Show(int id)
{
  ...
}

viewmodel.ShowUrl picks up whatever the value is of the "id" parameter. So viewmodel.ShowUrl becomes "/Course/Show/151" (value of id is 151); I want to be able to set the id part on the client based on user interaction. I want the value of viewmodel.ShowUrl to be "/Course/Show".

This seems like a bug to me. I'm not telling Url.Action to include an id value. It's doing it on its own. If I want to set the id value then I would do something like this:

var viewmodel.ShowUrl = Url.Action("Show", "Course", new {id = somevalue});

So, how do you prevent MVC from adding the id value? I can hardcode viewmodel.ShowUrl to "/Course/Show" but that seems to be a kludgy solution. Thanks.

I cant remeber exactly but the `Routedata` is on `ViewData` and that's why it's passed. I think you can do `Url.Action("Show", "Course", new {});` or empty the `RouteData` on `ViewData` object. — Bart Calixto, Aug 12 '13 at 17:15

score 34 · Answer 1 · answered Jul 09 '14 at 06:59

34

Just came across the same problem and so you know, you can also just use an empty string:

@Url.Action("Show", "Course", new { id = "" })

answered Jul 09 '14 at 06:59

Ben Cull

9,434
7
43
38

Thanks @Ben. This is the only one that worked for me. – JRodd Aug 31 '18 at 19:45

score 15 · Answer 2 · edited May 23 '17 at 12:17

15

I know this is old, but I found this first, but didn't like any of these solutions, so I kept looking and found https://stackoverflow.com/a/19110921/1130636.

You can use UrlParameter.Optional to solve this problem

Url.Action("Show", "Course", new { id = UrlParameter.Optional })

edited May 23 '17 at 12:17

Community

1
1

answered Mar 13 '15 at 17:01

borigas

495
5
11

score 11 · Accepted Answer · answered Apr 18 '12 at 00:07

I'm guessing in your routing, you're not specifying that id is an optional parameter. Here's the default route in a sample project.

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

Note the inclusion of id = UrlParameter.Optional. Without that, you'd get the behavior you're describing because it thinks the id is mandatory.

On a side note, if your Show action doesn't always have an id then it should be nullable or provide a default.

public ActionResult Show(int? id)
public ActionResult Show(int id = 0)

Otherwise you'll get an error when you try loading the url without the id parameter.

URL.Action includes id when constructing URL

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