RadTextBox error prompt like RadNumericTextBox

[Nileshkumar]

Hi,
I have RadTextBox in my aspx page & i want to restrict user to enter any char except aplhabet. But when user enter any other char i want to display error prompt in radtextbox same like it will display in radNumericTextBox when user alphabets.
how can i implement like this?

[Princy]

Hello Nilesh,

You can restrict entering numbers in RadTextBox in the client event OnKeyPress as shown below. You can show a prompt like RadNumericTextBox by removing the "textbox._invalid" and calling the function updateCssClass().
aspx:

<telerik:RadTextBox ID="RadTextBox1" runat="server" >
    <ClientEvents OnKeyPress="keyPress" />
</telerik:RadTextBox>
<asp:Button ID="Button1" runat="server" OnClientClick="return OnClientClick();" Text="Alert" />

Javascript:

<script type="text/javascript">
  function keyPress(sender, args)
  {
        var text = sender.get_value() + args.get_keyCharacter();
        if (!text.match('^[0-9]+$'))//enter only numbers
            args.set_cancel(true);
  }

 function OnClientClick()
 {
   // show prompt like RadNumericTextBox
    var textbox = $find("<%= RadTextBox1.ClientID %>");
    textbox._invalid = true;
    textbox.updateCssClass();
    return false;
 }
</script>

Another suggestion is to use RadNumericTextBox which has all these functionalities implemented in itself. Check the following help documentation which explains more about this.
RadNumericTextBox Basics.

Thanks,
Princy.

[Nileshkumar]

Hi Princy,
I don't want this solution. When user enters numeric value in RadTextBox that time error prompt should display like RadNumericTextBox(While enter alphabets or Special characters). 
Please find attached snapshot " RadTextBox.png" for detail.

[Martin]

Hello Nileshkumar,

You can use a slightly modified version of the approach Princy suggested:

<script type="text/javascript">
    function KeyPress(sender, args)
    {
        if (args.get_keyCharacter().search('[0-9]')>-1)
        {
            args.set_cancel(true);
            sender._invalid = true;
            sender.updateCssClass();
        }
        else
        {
            sender._invalid = false;
            sender.updateCssClass();
        }
    }
</script>
<telerik:RadTextBox runat="server" ID="RTB1">
    <ClientEvents OnKeyPress="KeyPress" />
</telerik:RadTextBox>

I hope this helps.

Regards,
Martin
the Telerik team