Deal with checkboxes in field 55

// v 0.4 Revised January 10, 2013
// http://www.gravityhelp.com/forums/topic/change-option-value?replies=19#post-103945
// this code will apply to form 1 only
add_action('gform_pre_submission_filter_1', 'strip_pricing_again');
function strip_pricing_again($form) {
                $field_pair = array('input_1' => 'input_57',    // envia el Desayuno elegido al ZOHO
                                'input_2' => 'input_58',        // envia el Nº de personas  al ZOHO
                                'input_55' => 'input_59',       // envia los extras al ZOHO
                                'input_27' => 'input_60',       // envia forma de pago al ZOHO
                                'input_52' => 'input_61');      // envia la población al ZOHO

                // define the separator one time
                $needle   = '|';

                // loop through all the field pairs
                // the unmodified value is stored in $_POST[$original]
                // and after modification it will be assigned to $_POST[$hidden]
                foreach ($field_pair as $original => $hidden) {
                        // deal with field 55 differently because it is checkboxes
                        if($original == 'input_55') {
                                // start with an empty $result string
                                $result = '';
                                // there are 23 checkboxes but _10 and _20 are skipped, so we need to count to 25
                                for($i=1; $i <= 25; $i++) {
                                        // each checkbox choice
                                        $choice = $original . "_$i";
                                        // make sure the choice was submitted before checking the value
                                        if(isset($_POST[$choice])) {
                                                $haystack = $_POST[$choice];
                                                $result .= substr($haystack, 0, strpos($haystack, $needle)) . '; ';
                                        }
                                }
                                // assign the result string to the hidden field 60
                                // trim off the trailing semicolon and space first
                                $_POST[$hidden] = substr($result, 0, (strlen($result)-2));
                        }
                        else {
                                $haystack = $_POST[$original];
                                $result = substr($haystack, 0, strpos($haystack, $needle));
                                $_POST[$hidden] = $result;
                        }
                }

                // return the form
                return $form;
}