show preview of pdf file saved in gridfs on browser

Hi i'm using gridfs to store file in mongodb, I'm facing a problem when i try to show the large pdf file in browser, which is saved in gridfs, large files doesn't showing in browser, but small files showing. this is my code, service

public function getIpFileByFileId() {
    $request = $this->request;
    $dm = $this->container->get('doctrine_mongodb')->getManager('patient');
    $id = $request->get('fileId');
    //get doc
    $docIpMapping = $dm->getRepository('PatientDocumentsBundle:IPDocuments')->findOneBy([
        'id' => $id
    ]);
    $base64 = (base64_encode($docIpMapping->getFile()->getBytes()));
    $response['data'] = $base64;
    $response['msg'] = 'success';
    return $response;
}

in front end

Ajax(path, data).success(function (result) {
                        $("#pdfDiv").html('<iframe style="width:100%;height:500px;" src="data:application/pdf;base64,' + result.data + '"></iframe>');
                });

Is my code have any problem? how to display large files in front end?

Ans:  in your code from service returning base64 data, instead of base64 return $docIpMapping->getFile()->getBytes()

in controller return as 

return new Response($response['data'], 200, array(

            'Content-Type' => 'application/pdf'));

and in front end

var url = "{{ path('get_ip_file_by_id',{'fileId' : '_ID_'})}}".replace('_ID_', fileId);

                    $("#pdfDiv").html('<iframe style="width:100%;height:500px;" src="' + url + '"></iframe>');

here you can load in iframe without loading to new page.