How to use fallback routing in asp.net core? - asp.net-core

Question

I am using asp.net web-api with controllers.
I want to do a user section where one can request the site's address with the username after it like example.com/username. The other, registered routes like about, support, etc. should have a higher priority, so if you enter example.com/about, the about page should go first and if no such about page exists, it checks whether a user with such name exists. I only have found a way for SPA fallback routing, however I do not use a SPA. Got it working manually in a middleware, however it is very complicated to change it.
var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();
string[] internalRoutes = new string[] { "", "about", "support", "support/new-request", "login", "register" };
string[] userNames = new string[] { "username1", "username2", "username3" };
app.Use(async (context, next) =>
{
string path = context.Request.Path.ToString();
path = path.Remove(0, 1);
path = path.EndsWith("/") ? path[0..^1] : path;
foreach (string route in internalRoutes)
{
if (route == path)
{
await context.Response.WriteAsync($"Requested internal page '{path}'.");
return;
}
}
foreach (string userName in userNames)
{
if (userName == path)
{
await context.Response.WriteAsync($"Requested user profile '{path}'.");
return;
}
}
await context.Response.WriteAsync($"Requested unknown page '{path}'.");
return;
await next(context);
});
app.Run();

Answer 1

It's really straightforward with controllers and attribute routing.
First, add controller support with app.MapControllers(); (before app.Run()).
Then, declare your controller(s) with the appropriate routing. For simplicity, I added a single one that just returns simple strings.
public class MyController : ControllerBase
{
[HttpGet("/about")]
public IActionResult About()
{
return Ok("About");
}
[HttpGet("/support")]
public IActionResult Support()
{
return Ok("Support");
}
[HttpGet("/support/new-request")]
public IActionResult SupportNewRequest()
{
return Ok("New request support");
}
[HttpGet("/{username}")]
public IActionResult About([FromRoute] string username)
{
return Ok($"Hello, {username}");
}
}
The routing table will first check if there's an exact match (e.g. for /about or /support), and if not, if will try to find a route with matching parameters (e.g. /Métoule will match the /{username} route).