Pods::add_to PHP Method

    public function add_to($field, $value, $id = null)
    {
        $pod =& $this;
        $fetch = false;
        if (null === $id) {
            $fetch = true;
            $id = $this->id();
        } elseif ($id != $this->id()) {
            $pod = pods($this->pod, $id);
        }
        $this->do_hook('add_to', $field, $value, $id);
        if (!isset($this->fields[$field])) {
            return $id;
        }
        // Tableless fields
        if (in_array($this->fields[$field]['type'], PodsForm::tableless_field_types())) {
            if (!is_array($value)) {
                $value = explode(',', $value);
            }
            if ('pick' == $this->fields[$field]['type'] && in_array($this->fields[$field]['pick_object'], PodsForm::simple_tableless_objects())) {
                $current_value = $pod->raw($field);
                if (!empty($current_value) || !is_array($current_value) && 0 < strlen($current_value)) {
                    $current_value = (array) $current_value;
                } else {
                    $current_value = array();
                }
                $value = array_merge($current_value, $value);
            } else {
                $related_ids = $this->api->lookup_related_items($this->fields[$field]['id'], $this->pod_data['id'], $id, $this->fields[$field], $this->pod_data);
                foreach ($value as $k => $v) {
                    if (!preg_match('/[^0-9]/', $v)) {
                        $value[$k] = (int) $v;
                    }
                }
                $value = array_merge($related_ids, $value);
            }
            if (!empty($value)) {
                $value = array_filter(array_unique($value));
            } else {
                $value = array();
            }
            if (empty($value)) {
                return $id;
            }
        } elseif (in_array($this->fields[$field]['type'], PodsForm::number_field_types())) {
            $current_value = (double) $pod->raw($field);
            $value = $current_value + (double) $value;
        } elseif (in_array($this->fields[$field]['type'], PodsForm::date_field_types())) {
            $current_value = $pod->raw($field);
            if (0 < strlen($current_value)) {
                $value = strtotime($value, strtotime($current_value));
            } else {
                $value = strtotime($value);
            }
        } elseif (in_array($this->fields[$field]['type'], PodsForm::text_field_types())) {
            $current_value = $pod->raw($field);
            if (0 < strlen($current_value)) {
                $value = $current_value . $value;
            }
        }
        // @todo handle object fields and taxonomies
        $params = array('pod' => $this->pod, 'id' => $id, 'data' => array($field => $value));
        $id = $this->api->save_pod_item($params);
        if (0 < $id && $fetch) {
            $pod->fetch($id, false);
        }
        return $id;
    }