Lesson 12. Data Validation

Many applications collect information from usersphone numbers, email addresses, and so onfor later use, or to send to a database where the data can be stored and retrieved as needed. However, if an application trusted users to enter properly formatted, error-free information, the application probably wouldn't function properlyor your database would quickly fill with useless data. The fact is that users often enter data incorrectly, which is why it's a good idea to validate data before it's used or processed. Validating data usually entails writing a script to check the way data was entered against a set of guidelines or rules. If data-entry errors are found, the user can be prompted to reenter the data; or in some cases, the script can make the needed adjustments without further input from the user.

Our fictional product contains a product registration form that allows us to collect data from the user, validate it, and display any errors found.

In this lesson, we'll create an application that includes a form requiring user-input data that needs to be validated. After our application validates this information, the app will display a custom confirmation page and then send the data to a server for processing.