Gravity Forms Filter out Spam by Keywords

A client of mine was beginning to get a ton of spam through their contact form on their website and it seemed to be manual submissions because Captcha and other antispam bot efforts were not working.  Many of the spam entries were for SEO services or other web related marketing tactics.  One thing I noticed was that there were consistent keywords being used in these solicitations and I though if I could block those keywords I could prevent alot of the spam coming through the site.

Gravity Forms  for WordPress has all sorts of great addons both free and paid however this sort of keyword filtering is not an addon I could find.  I did some Google searches and came across a great post detailing how to accomplish exactly what I wanted. The only downside to this is you need access to your functions.php file and it cannot be implemented through a plugin.  Maybe soon someone will take this on as a plugin but until then here is how to accomplish this:

/* 
 * Use an array to search a string
 * Allows us to pass the stop words list and our post data
 */
function strpos_arr($haystack, $needle) {
    if(!is_array($needle)) $needle = array($needle);
    foreach($needle as $what) {
        if(($pos = stripos($haystack, $what))!==false) return $pos;
    }
    return false;
}
 
/*
 * Our bad words validation function
 */
add_filter('gform_validation', 'custom_validation');
function custom_validation($validation_result){
    $form = $validation_result["form"];
 
	$stop_words = array(
		'outsource',
		'Sir/Madam',
		'Sir/ Madam',
		'Sir / Madam',
		'Sir /Madam',
		'long term relationship',
	);
 
	$stop_id = array();
 
	foreach($_POST as $id => $post)
	{
		if(strpos_arr($post, $stop_words))
		{
			/*
			 * We have a match so store the post ID and initiate validation error
			 */	
			 $stop_id[] = $id;
		}
	}
 
	if(sizeof($stop_id) > 0)
	{
		$validation_result['is_valid'] = false;
 
		foreach($form['fields'] as &$field) 
		{
			foreach($stop_id as $id)
			{
				$the_id = (int) str_replace('input_', '', $id);
 
				if($field['id'] == $the_id)
				{
					$field['failed_validation'] = true;
					$field['validation_message'] = 'Please do not send us unsolicited messages';
				}
			}
		}
	}
 
    //Assign modified $form object back to the validation result
    $validation_result["form"] = $form;
    return $validation_result;
 
}

To add your keywords to the code just replace the words in the section called $stop_words with your own.

Thank you to http://www.blueliquiddesigns.com.au/ for this awesome bit of code.

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