File upload validation

[eluser]stef25[/eluser]
ok here we go. these are two function in my controller. whether or not i pick a file for upload, i always get "You did not select a file to upload."

im wondering - what do you use as the first parameter inthe set_rules function? the name of the field or 'userfile' (someone mention this was required, but what if you have multiple file upload fields?) or, $_FILES['prod_img'] ?

Code:

function create() {    
            
            
            //validation
            $this->form_validation->set_rules('prod_name', 'product name', 'trim|required');
            $this->form_validation->set_rules('prod_img', 'product image', 'callback__do_upload');    
            $this->form_validation->set_rules('prod_descr_long', 'long description', 'trim|required');
            $this->form_validation->set_rules('prod_aff_link', 'affiliate link', 'trim|required');
                    
            
            if($this->form_validation->run() == FALSE) {                
                //send back to the view
                $attributes['prod_name'] = $this->input->post('prod_name');
                $attributes['prod_descr_long'] = $this->input->post('prod_descr_long');
                $attributes['prod_aff_link'] = $this->input->post('prod_aff_link');    
            
                $this->load->view('admin_view', $attributes);    
            }
            else {                
                $this->M_Products->createProduct();
                $this->load->view('admin_view', $attributes);
            }        
          }
          
          
          function _do_upload($file) {
              $config['upload_path'] = '/Applications/MAMP/htdocs/my-site/images/_uploads/';
            
            $this->load->library('upload', $config);
                
            if (!$this->upload->do_upload()) {
                //print "one"; exit;
                // set the validation error using the errors provided by the upload class
                $this->form_validation->set_message('_do_upload', $this->upload->display_errors());
                return FALSE;
            }    
            else {
                print "two"; exit;
               print_r($_FILES); exit;
            }
          }

thanks for any pointers!