How to Use a RequiredFieldValidator

When you need to make sure a field is filled out by the people visiting your website, you don't need a lot of complicated code in a variety of scripting languages. VB ASP.NET is up to the task!

Instructions

Difficulty: Moderate

Things You’ll Need:

• Microsoft Visual Studio 2005
• IIS & ASP.NET ready computer and/or
• ASP.NET ready Hosting services

1. Create the table Let's create a sample form on which we can play, one that is something you would use in real life. Create a table with four rows and two columns. Merge the cells in the first and last rows.
2. First thing to do, add in the verbiage so we know what we're looking. Row 1: "Login Page"
   Row 2 Column 1: "User Name: "
   Row 3 Column 1: "Password: "
3. Completed Table From the Toolbox, add the following:
   Row 2 Column 2: HTML Input box type=text
   Row 3 Column 3: HTML Input box type=password
   Row 4: Button
4. There are a couple properties to be specified in the input boxes. We must include "ID" and "runat". In the User Name Input box add: id="txtUserName" runat="server". In the Password Input box: id="txtPassword" runat="server".
5. Change the name of the button to "Login" and add an OnClick event through the Events window available while in Design view. It can be left empty.
6. While in source view, place your cursor immediately after the Input box closing tag. Insert a RequiredFieldValidator from the Toolbox. An open and close tag will be created for you, along with some default information. In-between the new tags, insert an asterisk which will server as the reminder that information is missing. To make the aster stand out, add the following to open Validator tag:
   
   Forecolor="red"
7. As it stands the Validator checks nothing. To make it keep a watchful eye on the UserName Input box, add the following to the open Validator tag:
   
   ControlToValidate="txtUserName"
8. Design View Repeat the previous two step for the txtPassword Input box. Insert the validator, add the asterisk, change the Forecolor to red and finally add the ControlToValidate. Be sure to change use "txtPassword" rather than "txtUserName". If you forget, both validators will be watching the same Input box.
9. Run the VB web application to test it. Try leaving the User Name empty. Once the button is clicked, the Validator is fired and the red asterisk becomes visible. The Validator will not allow the form to be submitted until the field has content. When the requirement has been met, the red asterisk will disappear.