php - Saving generated pdf directly to a folder folder - Codeigniter -

i generate , send created pdf folder error, error :

a php error encountered  severity: warning  message: file_put_contents(http://localhost/nqcl1/workbooks/ndqa000000001/ndqa000000001.pdf) [function.file-put-contents]: failed open stream: http wrapper not support writeable connections  filename: libraries/dompdf_lib.php  line number: 13 

dompdf_lib.php //library file

class dompdf_lib extends dompdf{          function createpdf($html, $filename='', $stream=true){               $this->load_html($html);             $this->render();             $this->set_paper('a4', 'potratit');             if ($stream) {                 //$this->stream($filename.".pdf"); - works ok                 file_put_contents(base_url().'workbooks/s'.$filename.'/'.$filename.".pdf", $this->output());               } else {                 return $this->output();             }         }  } 

coa.php //controller

function generatecoadraft($labref,$offset=0) {     // error_reporting(1);     $data['labref'] = $labref = $this->uri->segment(3);     $data['information'] = $this->getrequestinformation($labref);     $data['tests_requested'] = $this->getrequestedtests($labref);     $data['trd'] = $this->getrequestedtestsdisplay2($labref);     $data['compedia_specification'] = $this->getcoabody($labref);    $html = $this->load->view('coa_v', $data, true);    $this->dompdf_lib->createpdf($html, $labref); } 

this line works fine if use instead of file_put...., if stream=false, return blank page

$this->stream($filename.".pdf");  

file_put_contents native php function, change line to;

file_put_contents('workbooks/s'.$filename.'/'.$filename.".pdf", $this->output()); 

by prepending $this-> system trying find function belongs class (which doesn't exist), hence error.