Provides a FormField which allows form to validate for non-bot submissions by giving them a challenge to decrypt an image.

• Ingo Schommer (Nickname: ischommer, chillu) <ingo (at) silverstripe (dot) com>

• SilverStripe framework 3.1 or newer
• curl PHP module
• Requires spamprotection module

• Copy the recaptcha directory into your main SilverStripe webroot
• Run ?flush=1

This should go in your mysite/_config.php. You can get an free API key at http://www.google.com/recaptcha

RecaptchaField::$public_api_key = '<publickey>';
RecaptchaField::$private_api_key = '<privatekey>';

If using on a site requiring a proxy server for outgoing traffic then you can set these additional
options in your `mysite/_config.php`. 

RecaptchaField::$proxy_server = "<proxy address>";
RecaptchaField::$proxy_auth = "<proxy_username>:<proxy_password>";

If you want to use Recaptcha field by itself, you can simply just include it as a field in your form.

$recaptchaField = new RecaptchaField('MyCaptcha');
$recaptchaField->jsOptions = array('theme' => 'clean'); // optional

See Recaptcha API docs for more configuration options.

This requires the spamprotection module to be installed, see its documentation for details. You can use this field to protect any built informs on your website, including user comments in the [[:modules:blog]] module.

Configuration example in mysite/_config/spamprotection.yml

---
name: spamprotection
---
FormSpamProtectionExtension:
  default_spam_protector: RecaptchaProtector

Then once you have setup this config you will need to include the spam protector field as per the instructions on the spamprotection page.

The standard themes may be too limiting for your needs.

Adding the following configuration to your _config.php file, will automatically set the field to use a customisable template:

	RecaptchaField::$js_options = array(
		'theme' => 'custom',
		'custom_theme_widget' => 'recaptcha_widget'
	);

You can edit the design template by creating your own [themedir]/templates/CustomRecaptchaField.ss file.

ReCAPTCHA current does not work if the page doctype is XHTML. The API returns Javascript which uses "document.write", which is not supported in XHTML. A work-around is to always use the no-script version of the module (modify the relevant lines in RecaptchaField.php), or to switch your webpage's doctype to HTML 4. See: http://www.w3schools.com/tags/tag_DOCTYPE.asp

There is an issue that with certain site configurations, forms just won't submit in IE9.
Several threads are pointing to that IE9 and reCaptcha just won't work together, and this thread suggests to force Internet Explorer in IE8 mode: http://answers.microsoft.com/en-us/ie/forum/ie9-windows_7/ie9-is-not-capturing-recaptcha-form-fields/6479d1f0-6f67-e011-8dfc-68b599b31bf5?msgId=44883943-036d-e011-8dfc-68b599b31bf5&page=1

What can be done to circumvent this (but isn't optimal, as many sites look much better in IE9/10 than in IE8), is to force all UserDefineForms pages to be rendered in IE8 mode like described below (off course that can be extended to include other page types as well).
Though it's not optimal at all, it can be a good trade-off, considering that users are at least able to submit forms.

/*
 * Forcing the browser to render in IE8 mode for UserDefineForms
 * This is due to problems with IE9 and reCaptcha
 */
public function ForceIE8(){
	$class = $this->ClassName;
	if ($class == 'UserDefinedForm') {
		return true;
	}
}

...and adding this as first in the head tag

<% if ForceIE8 %>
	<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE8" >
<% end_if %>