Api Versioning break CreatedAt on MVC Core 2.2

[vanbukin]

If I make GET request on http://localhost:5000/api/v1/values/42, then I've got the following result

{
    "value": "model 42"
}

and it's ok. Bui if I make a POST on http://localhost:5000/api/v1/values
with following body

{
    "value": 42
}

I've got the following stacktrace

fail: Microsoft.AspNetCore.Server.Kestrel[13]
      Connection id "0HLIS5H63UVVC", Request id "0HLIS5H63UVVC:00000003": An unhandled exception was thrown by the application.
System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.AspNetCore.Mvc.Routing.ApiVersionRouteConstraint.Match(HttpContext httpContext, IRouter route, String routeKey, RouteValueDictionary values, RouteDirection routeDirection)
   at Microsoft.AspNetCore.Routing.Template.TemplateBinder.TryProcessConstraints(HttpContext httpContext, RouteValueDictionary combinedValues, String& parameterName, IRouteConstraint& constraint)
   at Microsoft.AspNetCore.Routing.DefaultLinkGenerator.TryProcessTemplate(HttpContext httpContext, RouteEndpoint endpoint, RouteValueDictionary values, RouteValueDictionary ambientValues, LinkOptions options, ValueTuple`2& result)
   at Microsoft.AspNetCore.Routing.DefaultLinkGenerator.GetPathByEndpoints(List`1 endpoints, RouteValueDictionary values, RouteValueDictionary ambientValues, PathString pathBase, FragmentString fragment, LinkOptions options)
   at Microsoft.AspNetCore.Routing.DefaultLinkGenerator.GetPathByAddress[TAddress](HttpContext httpContext, TAddress address, RouteValueDictionary values, RouteValueDictionary ambientValues, Nullable`1 pathBase, FragmentString fragment, LinkOptions options)
   at Microsoft.AspNetCore.Routing.LinkGeneratorRouteValuesAddressExtensions.GetPathByRouteValues(LinkGenerator generator, HttpContext httpContext, String routeName, Object values, Nullable`1 pathBase, FragmentString fragment, LinkOptions options)
   at Microsoft.AspNetCore.Mvc.Routing.EndpointRoutingUrlHelper.Action(UrlActionContext urlActionContext)
   at Microsoft.AspNetCore.Mvc.UrlHelperExtensions.Action(IUrlHelper helper, String action, String controller, Object values, String protocol, String host, String fragment)
   at Microsoft.AspNetCore.Mvc.UrlHelperExtensions.Action(IUrlHelper helper, String action, String controller, Object values, String protocol, String host)
   at Microsoft.AspNetCore.Mvc.CreatedAtActionResult.OnFormatting(ActionContext context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ObjectResultExecutor.ExecuteAsync(ActionContext context, ObjectResult result)
   at Microsoft.AspNetCore.Mvc.ObjectResult.ExecuteResultAsync(ActionContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeResultAsync(IActionResult result)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResultFilterAsync[TFilter,TFilterAsync]()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResultExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeResultFilters()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[2]
      Request finished in 191.4428ms 500

I can put breakpoint inside Post action and see that it calls correctly. The problem is somewhere inside CreatedAtAction.

Here is minimal repro
.csproj

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.2</TargetFramework>
    <AspNetCoreHostingModel>OutOfProcess</AspNetCoreHostingModel>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="Microsoft.AspNetCore.Razor.Design" Version="2.2.0" PrivateAssets="All" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc.Versioning" Version="3.0.0-beta2" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc.Versioning.ApiExplorer" Version="3.0.0-beta2" />
  </ItemGroup>

</Project>

and Program.cs

using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.DependencyInjection;

namespace ApiVersionTrouble
{
    public static class Program
    {
        public static void Main(string[] args)
        {
            CreateWebHostBuilder(args).Build().Run();
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args)
        {
            return WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>();
        }
    }

    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            var builder = services.AddMvc();
            builder.SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
            services.AddApiVersioning();
            services.AddVersionedApiExplorer();
        }

        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            app.UseMvc();
        }
    }

    [ApiController]
    [ApiVersion("1.0")]
    [Route("api/v{version:apiVersion}/values")]
    [Produces("application/json")]
    public class ValuesController : ControllerBase
    {
        [HttpGet("{settingsId:long}")]
        public ValueResponse Get([FromRoute] long settingsId)
        {
            return new ValueResponse(settingsId);
        }

        [HttpPost]
        public ActionResult Post([FromBody] ValueInput model)
        {
            var response = new ValueResponse(model.Value);
            return CreatedAtAction(
                nameof(Get),
                new {version = "1", settingsId = model.Value},
                response);
        }
    }

    public class ValueInput
    {
        public long Value { get; set; }
    }

    public class ValueResponse
    {
        public ValueResponse(long id)
        {
            Value = "model " + id.ToString("D");
        }

        public string Value { get; }
    }
}

[AdamWillden]

@vanbukin I had same thing and am raising issue on aspnetcore. you can get behaviour back if you set EnableEndpointRouting flag false in MvcOptions within AddMvc(options => ...)

[AdamWillden]

I'll link to this issue just in case the issue is here but I think it's the new Endpoint Routing

[AdamWillden]

dotnet/aspnetcore#4502

[commonsensesoftware]

@vanbukin, @AdamWillden is correct. 2.2 introduces a new type of routing system called Endpoint Routing, which is the new default. You can use the legacy routing mechanism by disabling this in the options. I've been aware of this change for some time and, in fact, some of those design driving the routing changes come from my feedback. Unfortunately, the ASP.NET has an entire platform team and I'm just one guy. I'm not even part of the ASP.NET team.

You can kvetch to the ASP.NET team, but we already have fairly regular discussions.

That said, I'm working toward supporting this as quickly as possible. The largest barrier isn't the changes in code, but the amount of testing and coordinating that the API Versioning 3.0 release. The 3.0 release brings a lot of fixes and other great features that do not depend on 2.2. If I jump the gun and force that immediately, all library consumers have to move up to 2.2, which is almost certainly not viable for everyone.

I had a recent chat with the ASP.NET team and their LTS story will be on 2.1 and that isn't expected to change again until 3.1. My current plan is to release 3.0, which only depends on 2.1. That will have a good story for existing adopters for the foreseeable future. I don't have the capacity to maintain a ton of version variations, so I definitely won't backport features and bug fixes will have to absolutely critical for me to consider them on older versions. The reported issues have dropped significantly since the Beta 2 release, which indicates stability and has given me some bandwidth. I anticipate that the official release will be later this month. The changes to support Endpoint Routing should be mostly internal shuffling and minor refactoring. I don't have a firm date, but I anticipate that it will be sometime in January.

I know the community is champing at the bit for this. I'm going as fast as my fingers and physics allow, but - again - I'm just one guy. I still have to do my day job on top of it. Thanks for you patience.

[xakep139]

Not only CreatedAtAction() returns null, Url.AbsoluteAction() returns null too

[commonsensesoftware]

3.1 has been published and includes support for Endpoint Routing. All of the sample applications have been updated to use Endpoint Routing by default as well. Thanks.

[vanbukin]

@commonsensesoftware You are awesome! Thank you!

[AdamWillden]

@vanbukin let me know if you're still experiencing issues, I'm still seeing same issue with new 3.1 package.

/cc @commonsensesoftware