init backend

dotnet/AipsCore/Domain/Models/Whiteboard/Validation/WhitebordCodeCharsetRule.cs

@@ -0,0 +1,20 @@
+using AipsCore.Domain.Common.Validation.Rules;
+using AipsCore.Utility.Text;
+
+namespace AipsCore.Domain.Models.Whiteboard.Validation;
+
+public class WhitebordCodeCharsetRule : CharsetRule
+{
+    public WhitebordCodeCharsetRule(string stringValue)
+        : base(stringValue, GetWhiteboardCodeCharset())
+    {
+    }
+
+    private static char[] GetWhiteboardCodeCharset()
+    {
+        return Charset.GetNumericCharset();
+    }
+
+    protected override string ErrorCode => "whiteboard_code_charset";
+    protected override string ErrorMessage => "Whiteboard code must contain only numbers";
+}