Learning PHP

Chapter 7. Exchanging Information with Users: Making Web Forms

Form processing is an essential component of almost any web application. Forms are how users communicate with your server: signing up for a new account, searching a forum for all the posts about a particular subject, retrieving a lost password, finding a nearby restaurant or shoemaker, or buying a book.

Using a form in a PHP program is a two-step activity. Step one is to display the form. This involves constructing HTML that has tags for the appropriate user-interface elements in it, such as text boxes, checkboxes, and buttons. If you’re not familiar with the HTML required to create forms, the “HTML Forms” chapter in Elisabeth Robson and Eric Freeman’s Head First HTML and CSS (O’Reilly) is a good place to start.

When a user sees a page with a form in it, she inputs the requested information into the form and then clicks a button or hits Enter to send the form information back to your server. Processing that submitted form information is step two of the operation.

Example 7-1 is a page that says “Hello” to a user. If the page is loaded in response to a form submission, then it displays a greeting. Otherwise, the page displays a form with which a user can submit her name.

Example 7-1. Saying “Hello”

if ('POST' == $_SERVER['REQUEST_METHOD']) {
    print "Hello, ". $_POST['my_name'];
} else {
    print<<<_HTML_
<form method="post" action="$_SERVER[PHP_SELF]">
 Your name: <input type="text" name="my_name" > ...