Bolt\Controller\Backend\Upload::uploadNamespace PHP Method

    public function uploadNamespace(Request $request, $namespace)
    {
        if ($handler = $request->get('handler')) {
            // Use custom handlers
            if (is_array($handler)) {
                return $this->processCustomUploadHandler($request, $handler);
            } else {
                list($namespace, $prefix) = $this->parser($handler);
                $this->app['upload.namespace'] = $namespace;
                $this->app['upload.prefix'] = $prefix;
            }
        } else {
            $namespace = $this->app['upload.namespace'];
        }
        // Perform the file upload actions and collect the results
        $fileUpload = $this->handleUploadFiles($request, $namespace);
        return $this->json($fileUpload, Response::HTTP_OK, ['Content-Type' => 'text/plain']);
    }