Programming ASP.NET, 3rd Edition

Validation Groups

The examples shown in this chapter have been kept intentionally simple. In a real application, however, you might have a page with many controls on it. In addition, the page may be divided into sections, with more than one button that can submit the page, depending on what the user is doing.

At times, it is convenient to be able to say, “When I press the first button I want to validate only these first five controls, but when I press the second button I want to validate only the last four controls.” This allows you to create forms in which you expect that some of the controls will be invalid. For example, you might have a page in which you ask the user to enter her username and password (if registered) or to enter other information if creating a new account. Clearly, one or the other will be left blank.

To accomplish this, you set the ValidationGroup property on all the controls (and the button that submits the page) to the same value for each group. In the example described above, the first five controls and the first button might all have ValidationGroup set to GroupOne, yet all the other controls would have ValidationGroup set to GroupTwo.

To try this out, create a new web site called ValidationGroup and copy the CompareValidator web site as a starting point.

Make two changes. First, move the two rows for password entry after the row that holds the Submit button. Then, add an additional row after the passwords to hold a new button with the ID of btnPW and the text ...