Return a file instead of just a CSV text

AS1024.GeoFeed.MinimalAPI/Program.cs

@@ -9,6 +9,7 @@ using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 using System;
+using System.Text;
 
 namespace AS1024.GeoFeed.MinimalAPI
 {
@@ -48,7 +49,7 @@ namespace AS1024.GeoFeed.MinimalAPI
             app.Run();
         }
 
-        protected static async Task<string> GeoFeedDataRunner(IGeoFeedProvider provider,
+        protected static async Task<IResult> GeoFeedDataRunner(IGeoFeedProvider provider,
                 ILogger<Program> logger,
                 IGeoFeedPersistentCacheProvider cacheProvider,
                 IMemoryCache memoryCache,
@@ -67,20 +68,26 @@ namespace AS1024.GeoFeed.MinimalAPI
                     }
                 }
 
-                return feed.ToGeoFeedCsv();
+                return Results.File(Encoding.UTF8.GetBytes(feed.ToGeoFeedCsv()),
+                    "text/csv",
+                    "geofeed.csv");
+
             }
             catch (HttpRequestException ex)
             {
                 logger.LogWarning($"Temporary failure of retrieving GeoData from upstream. {ex}");
                 string geoFeedData = cacheProvider.GetGeoFeed();
-                return geoFeedData;
+
+                return Results.File(Encoding.UTF8.GetBytes(geoFeedData),
+                    "text/csv",
+                    "geofeed.csv");
             }
             catch (Exception ex)
             {
                 logger.LogError($"Error: {ex}");
             }
 
-            return "";
+            return Results.NoContent();
         }
     }
 }