Fix S6934 FP: Attributes implementing IRouteTemplateProvider or inheriting from RouteAttribute

[CaringDev]

Description

Using attributes inheriting from RouteAttribute / implementing IRouteTemplateProvider are not considered for S6934

Repro steps

public sealed class BarRouteAttribute() : RouteAttribute("/barrr/[controller]/[action]");

[BarRoute]
public class SomeController : ControllerBase // FP: S6934
{
    [HttpGet("foo")]
    public string Foo() => "Hi";
}

Expected behavior

No S6934

Actual behavior

False positive S6934 for controllers decorated with an attribute inheriting from RouteAttribute / implementing IRouteTemplateProvider

Known workarounds

None

Related information

• SonarAnalyzer.CSharp 9.23.0.88079

[mary-georgiou-sonarsource]

Hello @CaringDev,

Thank you for reporting this. I confirm it's a false positive.

[mary-georgiou-sonarsource]

@CaringDev Seeing this example, I'd like to ask what's the use case here so that we can understand better and improve our analyzer.
Why did you create this base class for the attribute?
Thanks!

[CaringDev]

We use two attributes for easy, consistent setup of controllers:

public sealed class ControllerRouteAttribute() : RouteAttribute("api/v{version:apiVersion}/[controller]");
public sealed class ActionRouteAttribute() : RouteAttribute("api/v{version:apiVersion}/[controller]/[action]");

Then, with "find usages", we can immediately see which controllers use "standard" behavior and which ones action method named routing. It also helps to devs (first two are not convention aware):

    [HttpGet("ActionMethod")]
    [HttpGet(nameof(ActionMethod))]
    [HttpGet("[action]")]
    public void ActionMethod() { /* ... */ }

We could also use e.g.

public static class Routes {
    public const string Controller = "api/v{version:apiVersion}/[controller]";
    public const string Action = "api/v{version:apiVersion}/[controller]/[action]";
}

[Route(Routes.Controller)]
public class FooController : ControllerBase { /* ... */ }

The FP should be fixed in any case though... I think there are as many legit use-cases as there are users out there :-)

[costin-zaharia-sonarsource]

If I understand correctly, we should actually look for all the attributes that implement IRouteTemplateProvider. ASP.NET Core uses the attributes that implement IRouteTemplateProvider to build the initial set of routes.

[mary-georgiou-sonarsource]

@CaringDev thanks a lot for the detailed explanation.
One last question: Did you consider the usage of Areas for this case?

[CaringDev]

Did you consider the usage of Areas for this case?

No, we have several ASP.Net Core WebAPI (non-MVC) projects... would you think Areas would be applicable there as well?
Given our current approach:

namespace Container;

[ControllerRoute]
public class FooController : ControllerBase
{
    [HttpGet]
    public string GetIndex() => "hi";
}

[ActionRoute]
public class BarController : ControllerBase
{
   [HttpPost]
   public void ServeDrinks() { }
}

this would involve changing ControllerRoute and ActionRoute to Area("Controller") and Area("Action") and adding corresponding conventions, no? I doubt there's a benefit here... or are you thinking of something else?

[mary-georgiou-sonarsource]

Thanks a lot again for the detailed reply, @CaringDev!
I did not have something particular in mind; I was just curious if you evaluated the Areas feature for this use case and, if yes, why you did not go with it.

I guess for this:

Then, with "find usages", we can immediately see which controllers use "standard" behavior and which ones action method named routing.

Areas might not work (but not sure).