Handling Redirects with Middleware in .Net

I had a need to do a load of redirects when migrating a site from one platform to Umbraco 13.

Here is how I handled the issue by using middleware and a csv file.

The CSV file was created by a client and would be updated / maintained by them so it made sense to use that as the "source of truth".

The CSV file looks a bit like this :

/old-page,/new-page
/another-old-page,/another-new-page

The CSV file is saved on the root of my solution for ease of access.

The Middleware code, which is saved in a file called RedirectMiddleware.cs looks like this:

namespace MySite.Web.Infrastructure.Middleware
{
	public class RedirectMiddleware
	{
		private readonly RequestDelegate _next;
		private readonly Serilog.ILogger _logger;
		private readonly Dictionary<string, string> _redirects;

		public RedirectMiddleware(RequestDelegate next, Serilog.ILogger logger)
		{
			_next = next;
			_logger = logger;
			_redirects = LoadRedirects();
		}

		public async Task InvokeAsync(HttpContext context)
		{
			if (_redirects.TryGetValue(context.Request.Path.Value, out var targetUrl))
			{
				_logger.Information($"Redirecting from {context.Request.Path} to {targetUrl}");
				context.Response.Redirect(targetUrl, true);
				return;
			}

			await _next(context);
		}

		private Dictionary<string, string> LoadRedirects()
		{
			var redirects = new Dictionary<string, string>();
			var filePath = Path.Combine(Directory.GetCurrentDirectory(), "redirects.csv");

			if (File.Exists(filePath))
			{
				var lines = File.ReadAllLines(filePath);
				foreach (var line in lines)
				{
					var parts = line.Split(',');
					if (parts.Length == 2)
					{
						redirects[parts[0].Trim()] = parts[1].Trim();
					}
				}
			}

			return redirects;
		}
	}
}

and then in my Startup.cs or Program.cs I just added the Middleware like :

app.UseMiddleware<RedirectMiddleware>();

And that is it. When I hit /old-page I am redirected to /new-page (as long as it exists, if it doesn't then I will still get a 404 error.

One thing to note, this is using Serilog.ILogger as it's within an Umbraco 13 site and this allows me to save to the log files within Umbraco.