How to enforce lowercase routes in .NET 6? - .net-6.0

Question

I would like to enforce lowercase routes in .NET 6 API project.
Here is my Program.cs:
var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
var app = builder.Build();
// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
app.UseSwagger();
app.UseSwaggerUI();
}
app.UseHttpsRedirection();
app.UseAuthorization();
app.MapControllers();
app.Run();
Here is my WeatherForecastController.cs:
using Microsoft.AspNetCore.Mvc;
namespace Weather.API.Controllers
{
[ApiController]
[Route("weatherforecast")]
public class WeatherForecastController : ControllerBase
{
private static readonly string[] Summaries = new[]
{
"Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
};
private readonly ILogger<WeatherForecastController> _logger;
public WeatherForecastController(ILogger<WeatherForecastController> logger)
{
_logger = logger;
}
[HttpGet(Name = "GetWeatherForecast")]
public IEnumerable<WeatherForecast> Get()
{
return Enumerable.Range(1, 5).Select(index => new WeatherForecast
{
Date = DateTime.Now.AddDays(index),
TemperatureC = Random.Shared.Next(-20, 55),
Summary = Summaries[Random.Shared.Next(Summaries.Length)]
})
.ToArray();
}
}
}
I expect only the lowercase route (https://localhost:7243/weatherforecast) to work, but the route w/ pascal/uppercase works as well (https://localhost:7243/Weatherforecast)
I thought I can add builder.Services.AddRouting(options => options.LowercaseUrls = true); and app.UseRouting(), but I'm still able to access the route with pascal/uppercase: https://localhost:7243/Weatherforecast.
Here is the modified Program.cs file that I tried, but doesn't work:
var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
builder.Services.AddRouting(options => options.LowercaseUrls = true);
builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
var app = builder.Build();
// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
app.UseSwagger();
app.UseSwaggerUI();
}
app.UseHttpsRedirection();
app.UseAuthorization();
app.UseRouting();
app.MapControllers();
app.Run();

Answer 1

To generate lowercase URLs, add the following to Program.cs.
(Note: this does not enforce lowercase URLs).
// generate lowercase URLs
builder.Services.Configure<RouteOptions>(options =>
{
options.LowercaseUrls = true;
});
var app = builder.Build();
To enforce lowercase URLs, create an IRule-based rule that will redirect any uppercase URLs to lowercase URLs.
see this stackoverflow answer and IRule-based rule documentation.
Once you created an IRule-based rule (i.e., RedirectLowerCaseRule), add the following to Program.cs:
var app = builder.Build();
// enforce lowercase URLs
// by redirecting uppercase urls to lowercase urls
var options = new RewriteOptions().Add(new RedirectLowerCaseRule());
app.UseRewriter(options);