Web Database Applications with PHP and MySQL, 2nd Edition

Case Study: Using Sessions in Validation

In this section, we use sessions to improve the user interaction with the phonebook details form developed in Chapter 8. The improvements focus on the interaction when the form is submitted and fields fail validation. We modify the scripts to:

• Display error messages interleaved with the phonebook's entry form widgets.

• Use session variables to pass back the submitted fields to the form generation script, saving the user the trouble of re-keying the data to correct the errors.

Improving the Phonebook Details Form

We designed several phonebook scripts in Chapter 8. In Example 8-7, the form generated by the script collects values to create a new entry. The script shown in Example 8-9 performs simple server-side validation of the form data, and inserts a row in the phonebook table if there are no errors. We improve these scripts in this section, but the techniques we show you can be easily adapted to the other phonebook scripts or to any form pages you've authored.

If validation fails, the script shown in Example 8-9 generates a page to display the errors to the user, and the user then follows a hypertext link back to the phonebook entry form to reenter the fields. The solution provided by Example 8-7 and Example 8-9 has three problems:

• The user is forced to reenter the entire phonebook entry form from scratch when an error is encountered during validation

• Example 8-9 displays all the errors in a stand-alone page with no connection to the form page, ...