When the RadComboBox is in IsEditable mode, how do I set the MaxLength and CharacterCasing properties of the TextBox used for entering data?

I think I may have found the answer.

Create an Attached Property in a helper class:


    public class EditableComboBox
    {

        public static int GetMaxLength(DependencyObject obj)
        {
            return (int)obj.GetValue(MaxLengthProperty);
        }

        public static void SetMaxLength(DependencyObject obj, int value)
        {
            obj.SetValue(MaxLengthProperty, value);
        }

        // Using a DependencyProperty as the backing store for MaxLength.
        public static readonly DependencyProperty MaxLengthProperty =
            DependencyProperty.RegisterAttached("MaxLength", typeof(int), typeof(EditableComboBox), new UIPropertyMetadata(OnMaxLengthChanged));


        private static void OnMaxLengthChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
        {
            var comboBox = obj as Telerik.Windows.Controls.RadComboBox;
            if (comboBox == null)
            {
                return;
            }

            comboBox.Dispatcher.BeginInvoke(DispatcherPriority.Loaded,
                (DispatcherOperationCallback)delegate
                {
                    TextBox textBox = (TextBox)comboBox.Template.FindName("PART_EditableTextBox", comboBox);

                    if (textBox != null)
                    {
                        textBox.SetValue(TextBox.MaxLengthProperty, e.NewValue);
                    }

                    return null;
                }
                , null);
        }

        public static int GetCharacterCasing(DependencyObject obj)
        {
            return (int)obj.GetValue(CharacterCasingProperty);
        }

        public static void SetCharacterCasing(DependencyObject obj, int value)
        {
            obj.SetValue(CharacterCasingProperty, value);
        }

        // Using a DependencyProperty as the backing store for CharacterCasing.
        public static readonly DependencyProperty CharacterCasingProperty =
            DependencyProperty.RegisterAttached("CharacterCasing", typeof(int), typeof(EditableComboBox), new UIPropertyMetadata(OnCharacterCasingChanged));


        private static void OnCharacterCasingChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
        {
            var comboBox = obj as Telerik.Windows.Controls.RadComboBox;
            if (comboBox == null)
            {
                return;
            }

            comboBox.Dispatcher.BeginInvoke(DispatcherPriority.Loaded,
                (DispatcherOperationCallback)delegate
                {
                    TextBox textBox = (TextBox)comboBox.Template.FindName("PART_EditableTextBox", comboBox);

                    if (textBox != null)
                    {
                        textBox.SetValue(TextBox.CharacterCasingProperty, e.NewValue);
                    }

                    return null;
                }
                , null);
        }

Then declare it in XAML:

        <ti:RadComboBox IsEditable="True" local:EditableComboBox.MaxLength="20"/>

where 'local' is the location of the class in your code

Hi Peter,

Thank you for contacting us.

We are glad that you have found a solution yourself. Your Telerik points have been updated.

If you need any further assistance concerning our controls please feel free to contact us again.

Greetings,
Konstantina
the Telerik team