Dropdown List:


Textbox:


 


The ASP.NET Interface Controls can be validated using ASP.NET validators. For the Button control, you can use
the CausesValidation and ValidationGroup properties to customize the validation process.

<obout:OboutDropDownList runat="server" ID="ddl1" ... />
<asp:RequiredFieldValidator runat="server"  ControlToValidate="ddl1" ... />

<obout:OboutTextBox runat="server" ID="txt1" />
<asp:RequiredFieldValidator runat="server"  ControlToValidate="txt1" ... />

<obout:OboutButton runat="server" Text="Validate" />
<obout:OboutButton runat="server" Text="Skip Validation"  CausesValidation="false" />
<obout:OboutButton runat="server" Text="Validate"  ValidationGroup="group1" />