silverstripe / silverstripe-asset-admin

        /** @var File $file */

        $file = $this->getList()->byID($id);

        if (!$file->canView()) {

            $this->httpError(403, _t(

                'SilverStripe\\AssetAdmin\\Controller\\AssetAdmin.ErrorItemPermissionDenied',

                'You don\'t have the necessary permissions to modify {ObjectTitle}',

                '',

                ['ObjectTitle' => $file->i18n_singular_name()]

            ));

            return null;

        }

        $scaffolder = $this->getFormBuilder($file);

        $form = $scaffolder->getForm('FileEditForm');

            ));

            return null;

        }

        if (!$record->canView()) {

            $this->httpError(403, _t(

                'SilverStripe\\AssetAdmin\\Controller\\AssetAdmin.ErrorItemPermissionDenied',

                'You don\'t have the necessary permissions to modify {ObjectTitle}',

                '',

                ['ObjectTitle' => $record->i18n_singular_name()]

            ));

            return null;

        }

        $handler = AddToCampaignHandler::create($this, $record);

        return $handler->Form($record);