$cookie_name = "ref_code";
    $ref_code = (isset($_GET['ref'])) ? $_GET['ref'] : '';
    $stored_ref_code = get_cookies($cookie_name);
	if ($ref_code && $stored_ref_code) {
	    add_filter( 'gform_field_value_yoyoyyo', 'set_gravity_field_value' );
	}
	else if ($ref_code && !$stored_ref_code) {
		set_cookies_ref($cookie_name, $ref_code);
	    add_filter( 'gform_field_value_yoyoyyo', 'set_gravity_field_value' );
	}
	else if($stored_ref_code){
	    add_filter( 'gform_field_value_yoyoyyo', 'set_gravity_field_value' );
	}


function get_cookies($cookie_name='')
{
	if(!isset($_COOKIE[$cookie_name])) {
		return false;
	} else {
		return $_COOKIE[$cookie_name];

	}
}

function set_cookies_ref($cookie_name='', $cookies_value = '')
{
    setcookie($cookie_name, $cookies_value, time() + (86400 * 30), "/"); // 86400 = 1 day

}

function get_compaign_no($ref_code){

	$args = array(
		'numberposts'	=> -1,
		'post_type'		=> 'estate_agent',
		'meta_key'		=> 'ref_code', // ref_code
		'meta_value'	=> $ref_code
	);


	// query
	$the_query = new WP_Query( $args );
	$compaign_no = $the_query['compaign_no'];
	wp_reset_query();
	//$compaign_no = 'qq';
	return $compaign_no;
}



function set_gravity_field_value( $compaign_no ) {
	$compaign_no = get_compaign_no(get_cookies('ref_code'));
     return $compaign_no;
}