ASP.NET Attribute Routing - Url.Action not working - asp.net

Question

This code works fine:
[RouteArea("Main", AreaPrefix = "Hello")]
[RoutePrefix("{orgCode}")]
public class ResponseController : BaseController {
[Route("Save/{formCode}/{responseId}")]
public ActionResult Save(string formCode, int responseId, string questionCode){}
}
and Url.Action("Save", "Response") produces, for example, /Hello/org123/Save/form/123
However, if the Route attribute is changed and another segment added:
[Route("Save/{formCode}/{responseId}/{questionCode}")]
then Url.Action("Save", "Response") produces an empty string.
Is there a limit to how many sections can be defined in the route?

Answer 1

Is there a limit to how many sections can be defined in the route?
No.
But MVC only can build URLs using route values that it knows about. This can be a combination of route values that are passed to the Url.Action() method and values that are in the current request (usually passed through the current URL).
When the framework tries to determine which route to use, it selects the first route that matches all of the route values (controller, action, and anything else) and matches all of the (optional) constraints.
The route will not match if all of the conditions below are true for any of the parameters:
Have no defaults
Are not marked UrlParameter.Optional (NOTE: Optional parameters may not have any non-optional parameters to the right of them)
Are not present in the current request
Are not explicitly passed as route values to Url.Action() (or other method that calls UrlHelper to generate a URL)
Have constraint rules that do not match
In short, a route only matches if all of the required parameters are provided and constraints are satisfied.
So, apparently there is no questionCode in the current context, and since it is required to build the URL, you get an empty string. Most likely you need to pass it explicitly.
Url.Action("Save", "Response", new { questionCode = "123" })
You should also be careful to always explicitly pass other parameters if there may be cases where they are not present in the URL.