Url.RouteUrl is blank in ASP.NET Core 3.0

[shapeh]

Describe the bug

We are upgrading an ASP.NET Core 2.2. MVC app to 3.0 but Url.RouteUrl gives blank href's and inconsistency on link creation. What are we doing wrong?

To Reproduce

Steps to reproduce the behavior:

1. Using this version of ASP.NET Core 3.0
2. Run this code:

Example 1 -wrong result
Returns https://example.org/us/blog/some-title-6 in 2.2 but is blank in 3.0:

string url = Url.RouteUrl("blog-details", new { title = item.Title, id = item.Id });

[Route("~/{lang}/blog/{title}-{id}", Name= "blog-details")]
public async Task<IActionResult> Details(string title, int id)
{
}

We have tried these constructions but result is not satisfactory:

<a asp-action="Details" asp-controller="Blog" asp-route-title="item.Title" asp-route-id="@item.Id">Link here</a>
url = Url.Action("Details", "Blog", new { id = item.Id, title = item.Title });
url = Url.RouteUrl(new { action = "Details", controller = "Blog", id = item.Id, title = item.Title });

// Returns https://example.org/us/blog/details/6?title=some-title

Startup.cs

public void ConfigureServices(IServiceCollection services)
{
    ...
    services.AddControllersWithViews(options =>
        {
            options.Filters.Add(new MiddlewareFilterAttribute(typeof(LocalizationPipeline)));
        })
        .AddViewLocalization(LanguageViewLocationExpanderFormat.SubFolder)
        .AddViewLocalization(LanguageViewLocationExpanderFormat.Suffix);
    services.AddRazorPages();

    services.AddRouting(options =>
    { 
        options.ConstraintMap.Add("lang", typeof(LanguageRouteConstraint));
        options.LowercaseUrls = true;
        options.AppendTrailingSlash = false;
    });
    ...
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    ...
    app.UseRouting();
    app.UseAuthentication();
    app.UseAuthorization();

    app.UseResponseCompression();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllers(); // attribute routing
        endpoints.MapControllerRoute("areas", "{lang:lang}/{area:exists}/{controller=Home}/{action=Index}/{id?}");
        endpoints.MapControllerRoute("LocalizedDefault", "{lang:lang}/{controller=Home}/{action=Index}/{id?}");
        endpoints.MapControllerRoute("Naked", "/{controller=Home}/{action=Index}");
        endpoints.MapHealthChecks("/health");
    });
}

Example 2 - wrong result
Returns https://example.org/us/home/pricing instead of
https://example.org/us/pricing

<a asp-controller="Home" asp-action="Pricing">Pricing</a>

[Route("~/{lang}/pricing")]
public async Task<IActionResult> Pricing()
{
    ...
}

Example 3 - correct result
Returns correct https://example.org/us/signup/customer

<a asp-controller="Signup" asp-action="Customer">Sign up</a>

[Route("~/{lang}/signup/customer")]
public IActionResult Customer()
{
   ...
}

Additional context

dotnet --info

.NET Core SDK (reflecting any global.json):
Version: 3.0.100
Commit: 04339c3a26

Runtime Environment:
OS Name: Windows
OS Version: 10.0.18362
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\3.0.100\

Host (useful for support):
Version: 3.0.0
Commit: 7d57652f33

.NET Core SDKs installed:
2.1.202 [C:\Program Files\dotnet\sdk]
2.1.502 [C:\Program Files\dotnet\sdk]
2.1.504 [C:\Program Files\dotnet\sdk]
2.1.505 [C:\Program Files\dotnet\sdk]
2.1.507 [C:\Program Files\dotnet\sdk]
2.1.602 [C:\Program Files\dotnet\sdk]
2.1.604 [C:\Program Files\dotnet\sdk]
2.1.700 [C:\Program Files\dotnet\sdk]
2.1.801 [C:\Program Files\dotnet\sdk]
2.1.802 [C:\Program Files\dotnet\sdk]
2.2.100 [C:\Program Files\dotnet\sdk]
2.2.102 [C:\Program Files\dotnet\sdk]
2.2.104 [C:\Program Files\dotnet\sdk]
2.2.105 [C:\Program Files\dotnet\sdk]
2.2.203 [C:\Program Files\dotnet\sdk]
2.2.301 [C:\Program Files\dotnet\sdk]
3.0.100 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.2.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.2.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.2.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.2.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.2.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.2.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.2.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.2.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.2.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.2.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.2.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.2.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Ref #12794

[javiercn]

@shapeh Thanks for contacting us.

In order for us to investigate this issue, could you please provide a link to a github repo with a minimal repro project and detailed steps to reproduce the issue?

[shapeh]

@javiercn Thanks for getting back so quickly. It is impossible for me to do a github repo given the size of the project + confidentiality.
We have a LocalizationPipeline.cs middleware responsible for reading a list of languages in appsettings.json and turning that in correct URL - e.g. "en-gb" will be mapped "/uk" in URL {lang} param.

using System.Collections.Generic;
using System.Globalization;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Localization;
using example.Helpers;
using Microsoft.Extensions.Configuration;
using System.IO;

namespace example
{
    public class LocalizationPipeline
    {
        public void Configure(IApplicationBuilder app)
        {
            var options = new RequestLocalizationOptions();
            ConfigureOptions(app, options);

            app.UseRequestLocalization(options);
        }

        public static void ConfigureOptions(IApplicationBuilder app, RequestLocalizationOptions options)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true);

            IConfigurationRoot configuration = builder.Build();

            AppLanguages languageSettings = new AppLanguages();
            GeneralConfiguration generalConfiguration = new GeneralConfiguration();
            configuration.GetSection("AppLanguages").Bind(languageSettings);
            configuration.GetSection("GeneralConfiguration").Bind(generalConfiguration);

            var supportedCultures = new List<CultureInfo>();
            foreach (Language lang_in_app in languageSettings.Dict.Values)
            {
                supportedCultures.Add(new CultureInfo(lang_in_app.Culture));
            }

            options.DefaultRequestCulture = new RequestCulture(culture: "en-gb", uiCulture: "en-gb");
            options.SupportedCultures = supportedCultures;
            options.SupportedUICultures = supportedCultures;
            options.RequestCultureProviders = new[] {
                new RouteDataRequestCultureProvider(languageSettings)
                {
                    Options = options,
                    RouteDataStringKey = generalConfiguration.RouteDataStringKey
                }
            };
            app.UseRequestLocalization(options);
        }
    }
}

And this is the LanguageRouteConstraint.cs

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using example.Helpers;
using System.IO;

namespace example
{

    public class LanguageRouteConstraint : IRouteConstraint
    {
        private readonly AppLanguages _languageSettings;

        public LanguageRouteConstraint()
        {
            var builder = new ConfigurationBuilder()
                    .SetBasePath(Directory.GetCurrentDirectory())
                    .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true);

            IConfigurationRoot configuration = builder.Build();

            _languageSettings = new AppLanguages();
            configuration.GetSection("AppLanguages").Bind(_languageSettings);
        }

        public bool Match(HttpContext httpContext, IRouter route, string routeKey, RouteValueDictionary values, RouteDirection routeDirection)
        {
            if (!values.ContainsKey("lang"))
            {
                return false;
            }

            var lang = values["lang"].ToString();
            foreach (Language lang_in_app in _languageSettings.Dict.Values)
            {
                if (lang == lang_in_app.Icc)
                {
                    return true;
                }
            }
            return false;
        }
    }
}

[mkArtakMSFT]

@shapeh we are not looking for the whole app, rather a minimalistic repro - trimmed down to only the changes on top of a new project template, which demonstrates the issue.

[shapeh]

@mkArtakMSFT Got it / will see what I can do and revert :)

[mkArtakMSFT]

@shapeh we're closing this issue as we haven't heard back from you for some time now. Feel free to comment/reopen this issue when you have a repro available.

[shapeh]

Sorry about the late response - this is still open / I need just to free up an hour to do the repro.

[joeaudette]

I'm experiencing this issue as well in cloudscribe SimpleContent. I'm using named routes that expect a culture route constraint:

routes.MapControllerRoute(
           name: "pageedit-culture",
           pattern: "{culture}/editpage/{slug?}"
           , defaults: new { controller = "Page", action = "Edit" }
           , constraints: new { culture = cultureConstraint }
           );

but when I'm on a page like /fr/about which is the view url for a cms page, the culture parameter from the current url is not picked up when generating a link to the edit page like this:

 model.EditPath = Url.RouteUrl("pageedit-culture", new { slug = model.CurrentPage.Slug });

the model.EditPath ends up as null, whereas before 3.0 it would have been /fr/editpage/about

[mkArtakMSFT]

@joeaudette can you please provide a minimalistic repro (ideally GitHub hosted) so we can investigate this further?

[joeaudette]

@mkArtakMSFT cloudscribe is a pretty complex setup with route constraints for folder multi-tenancy and culture, I'm not sure I can create a small repro of the issue.

Endpoint routing was a major rewrite of the routing system so this is surely a bug. I hope you can investigate it on your end based on the description of the problem and not close the issue if I don't make a small repro for you.

For now I'm going to have to disable endpoint routing and go back to traditional mvc routing as a workaround, maybe I'll try endpoint routing again after you guys ship the next version or patch.