In this example, we will simply check the length of the string in the TextBox. This is a very basic and that useful example, only made to show you how you may use the CustomValidator.
<asp:TextBox runat="server" id="txtCustom" />
<asp:CustomValidator runat="server" id="cusCustom"
controltovalidate="txtCustom"
onservervalidate="cusCustom_ServerValidate"
errormessage="The text must be exactly 8 characters long!" />
As you can see, it’s pretty simple. The only unknown property is the onservervalidate event. It’s used to reference a method from CodeBehind which will handle the validation. Switch to our CodeBehind file and add the following method:
protected void cusCustom_ServerValidate(object sender, ServerValidateEventArgs e)
{
if(e.Value.Length == 3)
e.IsValid = true;
else
e.IsValid = false;
}
Hope this will Help you !!!
