Redisplaying a Form After PHP Validation

OK, back to form validation. So far we’ve created the HTML document validate.html, which will post through to the PHP program adduser.php, but only if JavaScript validates the fields, or if JavaScript is disabled or unavailable.

So now it’s time to create adduser.php to receive the posted form, perform its own validation, and then present the form again to the visitor if the validation fails. Example 17-3 contains the code that you should type in and save.

Example 17-3. The adduser.php program
<?php // adduser.php

// Start with the PHP code

$forename = $surname = $username = $password = $age = $email = "";

if (isset($_POST['forename']))
    $forename = fix_string($_POST['forename']);
if (isset($_POST['surname']))
    $surname = fix_string($_POST['surname']);
if (isset($_POST['username']))
    $username = fix_string($_POST['username']);
if (isset($_POST['password']))
    $password = fix_string($_POST['password']);
if (isset($_POST['age']))
    $age = fix_string($_POST['age']);
if (isset($_POST['email']))
    $email = fix_string($_POST['email']);

$fail  = validate_forename($forename);
$fail .= validate_surname($surname);
$fail .= validate_username($username);
$fail .= validate_password($password);
$fail .= validate_age($age);
$fail .= validate_email($email);

echo "<html><head><title>An Example Form</title>";

if ($fail == "") {
    echo "</head><body>Form data successfully validated: $forename,
        $surname, $username, $password, $age, $email.</body></html>";

    // This is where ...

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