antispam avoid spam captcha validation Completely Automated Public Turing test to tell Computers and Humans Apart
CAPTCHA validation
CAPTCHA validation is "a type of challenge-response test used in computing to determine whether or not the user is human" (for details see the related Wikipedia page) - in short, it's a great way to avoid form spamming.
To use the CAPTCHA validation, follow these steps:
- you can freely use your favourite CAPTCHA generator (eg. PEAR Text_CAPTCHA, pwImage, etc.) - the only requirement is to store the string used in the image in the
$_SESSIONarray. In general a CAPTCHA generator script is like:
<?php
$captcha = Text_CAPTCHA::factory( 'Image' );
$captcha->init(150, 60, NULL, array( 'font_file' => 'arial.ttf' ) );
header("Content-type: image/jpeg");
echo $captcha->getCAPTCHAAsJPEG();
$_SESSION['captchapass'] = $captcha->getPhrase();
?> - attach an
<img src="...">tag pointing to your CAPTCHA script: use the postfix setting of an inputText element - add the captcha validation to the inputText element: define the key of the $_SESSION variable ('captchapass' in the above example) in the
'index'setting of the validation array of the element - and now you're done!
<?php
$config = Array(
'element' => Array(
'type' => '...',
// ...further element settings here...
'validation' => Array(
Array(
'type' => 'captcha',
'index' => 'captchatext',
// 'index' is the $_SESSION array key:
// if your CAPTCHA image generator
// uses $_SESSION['captchatext'] to save
// the CAPTCHA letters, use 'captchatext'
// here
'casesensitive' => 0 | 1, // default: 0
// CAPTCHAs are typically case insensitive
'help' => 'Help message value for this validator only'
)
)
)
);
?>
Live examples:
form validation for developers!
clonefish is a proven, mature form generator class that helps PHP developers to create, validate and process secure, flexible and easy-to-maintain formslearn more
