You need to ensure that a user has entered data in a text box, such as a first or last name on a registration form.
RequiredFieldValidator control to the
use the event handler of the control that completes the
user’s entry for the page to verify that validation
RequiredFieldValidator control for each text
box in which data must be entered.
Add Save and Cancel (or equivalently named) buttons.
Set the Save button’s
CausesValidation attribute to
True to have validation performed when the button
is clicked (set it to
False for the Cancel
In the code-behind class, use the .NET language of your choice to add
code to the event handler for the Save button’s
click event that checks the
and verifies that all validation was successful.
Figure 2-1 shows a typical user input form with
fields for First Name and Last Name and several other types of
information. Figure 2-2 shows the same form with
validation error messages that appear when the user fails to complete
the First Name and Last Name fields. Example 2-1
.aspx file that implements the form,
and Example 2-2 and Example 2-3 show the VB and C# code-behind files needed to
complete the application.
Figure 2-1. Form with required field validation output—normal
Figure 2-2. Form with required ...