Configurable data directory for Docker + auto-add ExpiresAt column for existing databases

Program.cs

@@ -4,8 +4,12 @@ using NoticeBoard.Data;
 
 var builder = WebApplication.CreateBuilder(args);
 
-// SQLite database in app directory
-var dbPath = Path.Combine(builder.Environment.ContentRootPath, "noticeboard.db");
+// SQLite database. Defaults to the app's own directory (unchanged behaviour for IIS).
+// Set the "DataDirectory" setting (env var DataDirectory=... in Docker) to store the
+// database elsewhere — used by the Docker image so the DB lives on a mounted volume.
+var dataDir = builder.Configuration["DataDirectory"] ?? builder.Environment.ContentRootPath;
+Directory.CreateDirectory(dataDir);
+var dbPath = Path.Combine(dataDir, "noticeboard.db");
 builder.Services.AddDbContext<AppDbContext>(options =>
     options.UseSqlite($"Data Source={dbPath}"));
 
@@ -29,6 +33,32 @@ using (var scope = app.Services.CreateScope())
 {
     var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
     db.Database.EnsureCreated();
+
+    // This project doesn't use formal EF Core migrations — EnsureCreated only builds a
+    // brand-new database from the current model. For an existing Slides table (from before
+    // the ExpiresAt column existed), add it here so upgrades don't require a manual step.
+    var connection = db.Database.GetDbConnection();
+    await connection.OpenAsync();
+    var hasExpiresAt = false;
+    await using (var checkCmd = connection.CreateCommand())
+    {
+        checkCmd.CommandText = "PRAGMA table_info(Slides);";
+        await using var reader = await checkCmd.ExecuteReaderAsync();
+        while (await reader.ReadAsync())
+        {
+            if (string.Equals(reader["name"]?.ToString(), "ExpiresAt", StringComparison.OrdinalIgnoreCase))
+            {
+                hasExpiresAt = true;
+                break;
+            }
+        }
+    }
+    if (!hasExpiresAt)
+    {
+        await using var alterCmd = connection.CreateCommand();
+        alterCmd.CommandText = "ALTER TABLE Slides ADD COLUMN ExpiresAt TEXT NULL;";
+        await alterCmd.ExecuteNonQueryAsync();
+    }
 }
 
 if (!app.Environment.IsDevelopment())