c# - Automatically generate lowercase dashed routes in ASP.NET Core

Question

ASP.NET Core uses CamelCase-Routes like http://localhost:5000/DashboardSettings/Index by default. But I want to use lowercase routes, which are delimitted by dashes: http://localhost:5000/dashboard-settings/index They're more common and consistent, cause my application extends a website running Wordpress, which also has lowercase urls with dashes.

I learned that I can change the urls to lowercase using the routing-options:

services.ConfigureRouting(setupAction => {
    setupAction.LowercaseUrls = true;
});

This works but gave me urls without any delimiter like http://localhost:5000/dashboardsettings/index which are badly readable. I could define custom routes using the route attribute like

[Route("dashboard-settings")]
class DashboardSettings:Controller {
    public IActionResult Index() {
        // ...
    }
}

But that causes extra-work and is error-prone. I would prefer an automatic solution which search for uppercase chars, insert a dash before them and make the uppercase-char lowercase. For the old ASP.NET this was not a big issue, but on ASP.NET Core I see no direction how to handle this.

Whats the way to do this here? I need some kind of interface where I can generate urls (like for the tag helpers) and replace there the CamelCase by dash-delimiters. Then I need another kind of interface for the routing, so that the dash-delimiter urls are converted back to CamelCase for correct matching with my controller/action names.

Answer 1

Update in ASP.NET Core Version >= 2.2

To do so, first create the SlugifyParameterTransformer class should be as follows:

public class SlugifyParameterTransformer : IOutboundParameterTransformer
{
    public string TransformOutbound(object value)
    {
        // Slugify value
        return value == null ? null : Regex.Replace(value.ToString(), "([a-z])([A-Z])", "$1-$2").ToLower();
    }
}

For ASP.NET Core 2.2 MVC:

In the ConfigureServices method of the Startup class:

services.AddRouting(option =>
{
    option.ConstraintMap["slugify"] = typeof(SlugifyParameterTransformer);
});

And route configuration should be as follows:

app.UseMvc(routes =>
{
    routes.MapRoute(
       name: "default",
       template: "{controller:slugify}/{action:slugify}/{id?}",
       defaults: new { controller = "Home", action = "Index" });
 });

For ASP.NET Core 2.2 Web API:

In the ConfigureServices method of the Startup class:

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc(options => 
    {
        options.Conventions.Add(new RouteTokenTransformerConvention(new SlugifyParameterTransformer()));
    }).SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
}

For ASP.NET Core >=3.0 MVC:

In the ConfigureServices method of the Startup class:

services.AddRouting(option =>
{
    option.ConstraintMap["slugify"] = typeof(SlugifyParameterTransformer);
});

and route configuration should be as follows:

app.UseEndpoints(endpoints =>
{
    endpoints.MapAreaControllerRoute(
        name: "AdminAreaRoute",
        areaName: "Admin",
        pattern: "admin/{controller:slugify=Dashboard}/{action:slugify=Index}/{id:slugify?}");

    endpoints.MapControllerRoute(
        name: "default",
        pattern: "{controller:slugify}/{action:slugify}/{id:slugify?}",
        defaults: new { controller = "Home", action = "Index" });
});

For ASP.NET Core >=3.0 Web API:

In the ConfigureServices method of the Startup class:

services.AddControllers(options => 
{
    options.Conventions.Add(new RouteTokenTransformerConvention(new SlugifyParameterTransformer()));
});

For ASP.NET Core >=3.0 Razor Pages:

In the ConfigureServices method of the Startup class:

services.AddRazorPages(options => 
{
    options.Conventions.Add(new PageRouteTransformerConvention(new SlugifyParameterTransformer()));
});

This is will make /Employee/EmployeeDetails/1 route to /employee/employee-details/1