You need to make sure the data a user enters matches a specific pattern, such as an email address.
RegularExpressionValidator control to the
.aspx file, set the regular expression to
perform the pattern matching, and verify that validation was
successful from within the event handler of the control that
completes the user’s entry for the page.
RegularExpressionValidator control for each
text box that must have data matching a specific pattern.
ValidationExpression attribute of the
RegularExpressionValidator to the regular
expression needed to match the required pattern.
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 for the page, use the .NET language of your
choice to add code to the event handler for the Save
button’s click event to check the
Page.IsValid property and verify that all
validation was successful. (See Recipe 2.1 for details.)
Figure 2-7 shows a typical form with normal,
error-free output. Figure 2-8 shows the error
message that appears on the form when an invalid email address is
entered. Example 2-6 shows the
.aspx file for our application that implements
the recipe. See Example 2-2 and Example 2-3 (Recipe 2.1) for the companion code-behind
Figure 2-7. Form with pattern ...