Implementing a Custom Freeform Date Parser in RadDateTimePicker

Updated on Jan 8, 2026

Environment

Product Version	Product	Author
2025.4.1111	RadDateTimePicker for WinForms	Dinko Krastev

Description

In this article we will demonstrate how to enhance the functionality of the RadDateTimePicker by allowing users to input custom freeform text, such as "today - 4w" or "bomonth - 6m". The goal is to run a custom parser first, which processes the input according to specific rules. If the custom parser fails, the input should fall back to the standard parser.

Solution

To achieve the desired functionality, create a custom class that inherits from the FreeFormDateTimeProvider class. Override the OnParsingDateTime method to implement custom parsing logic. If your parser successfully parses the input, return the parsed result; otherwise, call the base method to fall back to the default parser.

1. Set the MaskType property of the RadDateTimePicker to FreeFormDateTime.
2. Assign your custom provider to the TextBoxElement.Provider property.
3. Implement your parsing logic in the overridden OnParsingDateTime method.

Example code:

C#

// Configure RadDateTimePicker to use FreeFormDateTimeProvider
radDateTimePicker1.DateTimePickerElement.TextBoxElement.MaskType = MaskType.FreeFormDateTime;
radDateTimePicker1.DateTimePickerElement.TextBoxElement.Provider = new MyFreeFormProvider(provider.Mask, provider.Culture, provider.Owner);

// Custom FreeFormDateTimeProvider class
public class MyFreeFormProvider : FreeFormDateTimeProvider
{
    public MyFreeFormProvider(string mask, CultureInfo culture, RadMaskedEditBoxElement owner) : base(mask, culture, owner)
    {
    }

    public override void OnParsingDateTime(ParsingDateTimeEventArgs e)
    {
        var inputString = e.InputString;

        // Custom parsing logic
        bool success = DateTime.TryParse(inputString, out DateTime parsedDate);
        if (success)
        {
            e.Result = parsedDate;
            return; // Exit if successfully parsed
        }

        // Fallback to base parser
        base.OnParsingDateTime(e);
    }
}