ApiController::actionUpdate PHP Method

    public function actionUpdate($resource_type, $id)
    {
        try {
            $ref = $this->getRef($resource_type, $id);
            $vid = $ref->getVersionId();
            $vurl = $this->createAbsoluteUrl('api/') . '/' . Yii::app()->service->referenceToFhirUrl($ref) . "/_history/{$vid}";
            if (isset($_SERVER['HTTP_CONTENT_LOCATION']) && $_SERVER['HTTP_CONTENT_LOCATION'] != $vurl) {
                $this->sendResponse(409);
            }
            if (isset($_SERVER['HTTP_IF_MATCH'])) {
                $match = false;
                foreach (str_getcsv($_SERVER['HTTP_IF_MATCH']) as $tag) {
                    if ($tag == $vid || $tag == '*') {
                        $match = true;
                        break;
                    }
                }
                if (!$match) {
                    $this->sendResponse(412);
                }
            }
            if (isset($_SERVER['HTTP_IF_UNMODIFIED_SINCE'])) {
                $since = strtotime($_SERVER['HTTP_IF_UNMODIFIED_SINCE']);
                if ($since === false) {
                    $this->sendError("Failed to parse If-Unmodified-Since header: {$_SERVER['HTTP_IF_UNMODIFIED_SINCE']}");
                }
                if ($ref->getLastModified() > $since) {
                    $this->sendResponse(412);
                }
            }
            $input = $this->parseInput();
            $tx = Yii::app()->db->beginTransaction();
            $ref->fhirUpdate($input);
            $tx->commit();
        } catch (\services\NotFound $e) {
            $this->sendError("Client defined IDs are not supported ({$e->getMessage()})", 405);
        }
        header("Location: {$vurl}");
        header("Content-Location: {$vurl}");
        header('Last-modified: ' . date(DATE_RFC1123, $ref->getLastModified()));
        header("ETag: \"{$vid}\"");
        $this->sendInfo("Resource {$resource_type}/{$id} successfully updated");
    }