Why does my blob not get sent?

Question

I am newbie trying to code a file upload validator that sends an image as a blob to a MySQL database. The image is taken from a gravity form file upload in wordpress (form ID is 1). When I run the below script, no blob is sent to my mallampati_images table, however the file format alert displays. It also outputs this error:

Warning: file_get_contents(/home/clients/4ceaa5faab208e8af4350138684e6d6d/web/wp-content/uploads/mallampati.png): failed to open stream: No such file or directory in /home/clients/4ceaa5faab208e8af4350138684e6d6d/web/wp-content/themes/twentytwelve/functions.php on line 535

What I do not understand is how to format the link to the file. I have been trying every way I could find on the net for some hours, but I cannot make it work. I edited the code below to return the link (that is a correct absolute link, it seems...)

The script:

function testimage($path)
{
   if(!preg_match("/\.(png|jpg|gif)$/",$path,$ext)) return 0;

   $ret = null;
   switch($ext[1])
   {
       case 'png': $ret = @imagecreatefrompng($path); break;
       case 'jpg': $ret = @imagecreatefromjpeg($path); break;
       case 'gif': $ret = @imagecreatefromgif($path); break;
       default: $ret = 0;
   }

   return $ret;
}

add_action("gform_after_submission_1", "input_fields", 10, 3);
function input_fields($entry){
    global $wpdb;

   if (isset($_FILES['input_1'])) {
     $file_url = $entry['1'];
     //$img_blob = file_get_contents($file_url);
     $validate = testimage($file_url);

     $udir = wp_upload_dir();
     $basedir = $udir['basedir'];
     $target=$basedir.'/'.basename($_FILES['input_1']['name']);

     //$try = $_FILES['input_1']['tmp_name'];
     $img_blob = file_get_contents ($target);
     echo "<script type='text/javascript'>alert('value: $target');</script>";
   }

  if(!empty($validate)) {
     echo "<script type='text/javascript'>alert('The file was of the correct format');</script>";

     $SQL = "INSERT INTO mallampati_images (img_blob) VALUES ( $img_blob )";
     $wpdb->query($SQL);
   }
}

Answer 1

I finally made it.

Gravity forms seems to not handle files exactly as examples I have been looking at. The problem was that it resulted in an incorrect file path being used in the SQL query.

function testimage($path)
{
   if(!preg_match("/\.(png|jpg|gif)$/",$path,$ext)) return 0;

   $ret = null;
   switch($ext[1])
   {
       case 'png': $ret = @imagecreatefrompng($path); break;
       case 'jpg': $ret = @imagecreatefromjpeg($path); break;
       case 'gif': $ret = @imagecreatefromgif($path); break;
       default: $ret = 0;
   }

   return $ret;
}

add_action("gform_after_submission_1", "input_fields", 10, 2);
function input_fields($entry){
    global $wpdb;

    if(isset($entry[1])){
      $valid = testimage($entry[1]);

      if($valid){
        $mpFilePath= $entry[1];
        $blob = file_get_contents($mpFilePath) or die ('cannot read file');
        $blob = mysql_escape_string($blob);
        $SQL = "INSERT INTO mallampati_images (img_blob) VALUES ( '$blob' )";
        $wpdb->query($SQL) or die ('query failed');
      }
      else{
        echo "<script type='text/javascript'>alert('Incorrect file format');</script>";
      }
    }
}