ASP.NET Validation

Example code

TextBox: <asp:textbox id="TextBox1" runat="server" />
<asp:RequiredFieldValidator ControlToValidate="TextBox1" EnableClientScript="True"
       text="TextBox content is empty" ValidationGroup="Group1" runat="server" />
...
<osb:SuperButton ValidationGroup="Group1" isSubmit="true" CausesValidation="true" Text="Submit" ... />

Download Download this working example.

This textbox should not be empty when submit:

TextBox:  

Submit