Using Zend_Captcha_ReCaptcha

Short introduction to using Zend_Captcha_ReCaptcha as a standalone entity. The Zend Framework manual does not cover the use of this component well; I am working on writing a more detailed manual entry for it, of which this is the first step.

This tutorial is aimed at developers who are introducing Zend Framework (ZF) components into existing non-ZF web sites (like me!), however it can easily be adapted for those who are creating new web sites based on ZF (ie: using Zend_Application).

Step 1: Create Service Object

Zend_Captcha_ReCaptcha communicates with Google's reCAPTCHA service via the Zend_Service_ReCaptcha class:

$recaptcha_service = new Zend_Service_ReCaptcha(
    $rcPublicKey,
    $rcPrivateKey
);

Where $rcPublicKey and $rcPrivateKey are your public and private keys, respectively.

Short introduction to using Zend_Captcha_ReCaptcha.

Step 2: Create instance of CAPTCHA

$adapter = new Zend_Captcha_ReCaptcha();
$adapter->setService( $recaptcha_service );

There are additional options you can provide to $adapter, all of which are documented in the API guide. If you are using Zend_Controller and Zend_View, this is the object you would assign to your view.

Step 3: Displaying the CAPTCHA

In the HTML page for your form, call the render function of $adapter to display the CAPTCHA:

echo $adapter->render();

Step 4: CAPTCHA Validation

In the PHP code which validates the form to which you added the CAPTCHA in Step 3, add the following to your validation routine:

$reUserData = array(
    'recaptcha_challenge_field' => $_POST['recaptcha_challenge_field'],
    'recaptcha_response_field' => $_POST['recaptcha_response_field']
);
if ( $adapter->isValid($reUserData) !== true )
{
    // Handle validation error
}

The important part to note here is that isValid() requires an associative array of the two reCAPTCHA form inputs, which neither the Zend Framework manual nor API guide stipulate.