Misleading MissingMethodException message for incorrect routes

[mafshin]

Having an incorrect route for action methods will throw misleading exception message.

Steps to reproduce:

• Create a new ASP.NET Core web project with WebAPI template
• Run the app the and ValuesController will work as excpected
• Add a regex(\\d+)' constraint to theidparameter of theValuesController.Get` method
• Run the app and it works just as expected
• Mistakenly add an incorrect route config like the below one (consider the extra double colon after regex)

        [HttpGet("{id:regex:(\\d+)}")]
        public string Get(int id)
        {
            return $"The content for document #{id}";
        }

• Run the app again and you will see the following misleading exception:

Microsoft.AspNetCore.Hosting.Internal.WebHost:Information: Request starting HTTP/1.1 DEBUG http://localhost:13367/  0
Microsoft.AspNetCore.Hosting.Internal.WebHost:Information: Request starting HTTP/1.1 GET http://localhost:13367/api/values  
Microsoft.AspNetCore.Hosting.Internal.WebHost:Information: Request finished in 93.9806ms 200 
Microsoft.AspNetCore.Server.Kestrel:Error: Connection id "0HKT7OA7R93TP": An unhandled exception was thrown by the application.

System.MissingMethodException: No parameterless constructor defined for this object.
   at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck)
   at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
   at System.Activator.CreateInstance(Type type, Boolean nonPublic)
   at System.Activator.CreateInstance(Type type)
   at Microsoft.AspNetCore.Routing.DefaultInlineConstraintResolver.CreateConstraint(Type constraintType, String argumentString)
   at Microsoft.AspNetCore.Routing.DefaultInlineConstraintResolver.ResolveConstraint(String inlineConstraint)
   at Microsoft.AspNetCore.Routing.RouteConstraintBuilder.AddResolvedConstraint(String key, String constraintText)
   at Microsoft.AspNetCore.Routing.Tree.TreeRouteBuilder.MapOutbound(IRouter handler, RouteTemplate routeTemplate, RouteValueDictionary requiredLinkValues, String routeName, Int32 order)
   at Microsoft.AspNetCore.Mvc.Internal.AttributeRoute.AddEntries(TreeRouteBuilder builder, ActionDescriptorCollection actions)
   at Microsoft.AspNetCore.Mvc.Internal.AttributeRoute.GetTreeRouter()
   at Microsoft.AspNetCore.Mvc.Internal.AttributeRoute.RouteAsync(RouteContext context)
   at Microsoft.AspNetCore.Routing.RouteCollection.<RouteAsync>d__9.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.<Invoke>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Server.IISIntegration.IISMiddleware.<Invoke>d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Hosting.Internal.RequestServicesContainerMiddleware.<Invoke>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Server.Kestrel.Internal.Http.Frame`1.<RequestProcessingAsync>d__2.MoveNext()
Microsoft.AspNetCore.Hosting.Internal.WebHost:Information: Request finished in 295.4269ms 200 

project.json

{
  "dependencies": {
    "Microsoft.NETCore.App": {
      "version": "1.0.0",
      "type": "platform"
    },
    "Microsoft.AspNetCore.Mvc": "1.0.0",
    "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0",
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.0",
    "Microsoft.Extensions.Configuration.EnvironmentVariables": "1.0.0",
    "Microsoft.Extensions.Configuration.FileExtensions": "1.0.0",
    "Microsoft.Extensions.Configuration.Json": "1.0.0",
    "Microsoft.Extensions.Logging": "1.0.0",
    "Microsoft.Extensions.Logging.Console": "1.0.0",
    "Microsoft.Extensions.Logging.Debug": "1.0.0",
    "Microsoft.Extensions.Options.ConfigurationExtensions": "1.0.0"
  },

  "tools": {
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final"
  },

  "frameworks": {
    "netcoreapp1.0": {
      "imports": [
        "dotnet5.6",
        "portable-net45+win8"
      ]
    }
  },

  "buildOptions": {
    "emitEntryPoint": true,
    "preserveCompilationContext": true
  },

  "runtimeOptions": {
    "configProperties": {
      "System.GC.Server": true
    }
  },

  "publishOptions": {
    "include": [
      "wwwroot",
      "Views",
      "Areas/**/Views",
      "appsettings.json",
      "web.config"
    ]
  },

  "scripts": {
    "postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ]
  }
}

Expected Behavior

• Ideal: To have a design time route config checking
• Normal: To have an exception message like this:
  An unhandled exception was thrown while constructing the route config for ValuesController.Get method. No parameterless constructor defined for regex:

At first I thought the problem was with my models so I commented here in DI repo.

[rynowak]

I'm not really sure what's up with the RegexRouteConstraint that's causing this issue.

In general though we should try to surface this error in a better way. We did a lot of work to collect most of the errors that can be thrown from attribute routing into a single group so that you can see all of the errors at once and not just the first one. It looks like we missed the case where a constraint throws.

[danroth27]

We should throw an exception with a better error message.