Why would a Web API entity collection GET work but the single entity GET return 404.0?

Question

We have an OData 4 WebAPI controller with two GET methods, one that returns a Thing entity collection (IQueryable<Thing>) and one that returns a single Thing (SingleResult<Thing>) based on the provided key (using the FromODataUri attribute).

When run, IIS and IISExpress happily return an entity collection when you request http://localhost:48213/odata/Things, but return a 404.0 - Not Found when we request a single entity on http://localhost:48213/odata/Things(1) (the notification coming from MapRequestHandler and the Handler being StaticFile). The GET method for the single entity is not executed.

The project was created following this tutorial and I think we've followed it correctly. This feels like a URL mapping issue (perhaps web.config or IIS/IISExpress config related), because the URL is extension-less and contains parentheses. However, I guess it could be the route configuration or some other thing I don't get. Does anybody have any ideas?

The Thing type declaration is as follows (in F#):

[<CLIMutable>]
type Thing =
    { Id   : string
      Name : string }

Answer 1

What is the type of the key parameter in your controller ? If it is string, you should have the url:

/odata/Things('1')