WPF - MVVM Textbox restrict to specific characters

Question

I am trying to make text box accept only specific characters.

My TextBox is bound to the following:

    private string _CompanyID;
    public string          


        

Answer 1

I do this with the PreviewtextInput event. I have a generic event used for multiple TextBoxes which takes the regex from a configuration table, but I have hard-coded the regex in this example.

private void GenericTextBox_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
   e.Handled = !IsTextAllowed(e.Text, @"[^a-zA-Z]");
}

private static bool IsTextAllowed(string Text, string AllowedRegex)
{
    try
    {
        var regex = new Regex(AllowedRegex);
        return !regex.IsMatch(Text);
    }
    catch
    {
        return true;
    }
}