How can I do this? I tried setting up a custom Data Filter but it isn't working.

The datatypes in the owner and editor are set to decimal.

public class DecimalInputDataFilter : IEditorDataFilter
    {
        private const string DecimalRegexPattern = @"(\-\.?\d{1}|\(\.?\d{1}|\.?\d{1}){1}\d*(\.\d*)?";
 
        public object Convert(EditorDataFilterConvertArgs args)
        {
            var cell = args.Context as UltraGridCell;
 
            if (cell == null)
            {
                args.Handled = false;
                return null;
            }
 
            var value = cell.Value as decimal?;
 
            switch (args.Direction)
            {
                case ConversionDirection.DisplayToEditor:
                    return CleanInput(value.ToString());
                case ConversionDirection.EditorToDisplay:
                    return value;
                case ConversionDirection.OwnerToEditor:
                    return value;
                case ConversionDirection.EditorToOwner:
                    return value;
            }
 
            args.IsValid = false;
            return null;
        }
 
        public static decimal CleanInput(string input)
        {
            if (string.IsNullOrWhiteSpace(input))
                return 0m;
 
            var match = Regex.Match(input.Replace(",", string.Empty), DecimalRegexPattern).Value;
 
            if (string.IsNullOrWhiteSpace(match))
                return 0m;
 
            var negative = match.StartsWith(@"-") || match.StartsWith(@"(");
 
            decimal result;
 
            if (negative)
            {
                if (decimal.TryParse(match.Substring(1), out result))
                    result *= -1;
            }
            else
            {
                decimal.TryParse(match, out result);
            }
 
            return result;
        }
    }