Modification d'un formulaire

Bonjour , j'ai un problème quand je veux modifié un produit il récupère le nom de l'image dans la quantité et il récupére pas l'image .

Merci

product_quantity= la quantité
product_image = l'image du produit

<?php
 include_once('includes/connect_database.php'); 
 include_once('functions.php'); 
?>
<div id="content" class="container col-md-12">
 <?php 
 
  if(isset($_GET['id'])){
   $ID = $_GET['id'];
  }else{
   $ID = "";
  }
  
  // create array variable to store category data
  $category_data = array();
   
  $sql_query = "SELECT cat_id, cat_title 
    FROM categories 
    ORDER BY cat_id ASC";
    
  $stmt_category = $connect->stmt_init();
  if($stmt_category->prepare($sql_query)) { 
   // Execute query
   $stmt_category->execute();
   // store result 
   $stmt_category->store_result();
   $stmt_category->bind_result($category_data['cat_id'], 
    $category_data['cat_title']
    );
    
  }
   
  $sql_query = "SELECT product_image FROM products WHERE product_id = ?";
  
  $stmt = $connect->stmt_init();
  if($stmt->prepare($sql_query)) { 
   // Bind your variables to replace the ?s
   $stmt->bind_param('s', $ID);
   // Execute query
   $stmt->execute();
   // store result 
   $stmt->store_result();
   $stmt->bind_result($previous_product_image);
   $stmt->fetch();
   $stmt->close();
  }
  
  
  // get currency symbol from setting table
  $sql_query = "SELECT Value 
    FROM tbl_setting 
    WHERE Variable = 'Currency'";
  
  
  $stmt = $connect->stmt_init();
  if($stmt->prepare($sql_query)) { 
   // Execute query
   $stmt->execute();
   // store result 
   $stmt->store_result();
   $stmt->bind_result($currency);
   $stmt->fetch();
   $stmt->close();
  } 
  
  
  if(isset($_POST['btnEdit'])){
   
   $product_title = $_POST['product_title'];
   $product_category_id = $_POST['$product_category_id'];
   $product_price = $_POST['product_price'];
   $serve_for = $_POST['serve_for'];
   $product_description = $_POST['product_description'];
   $product_quantity = $_POST['product_quantity'];
   
   // get image info
   $product_image = $_FILES['product_image']['name'];
   $image_error = $_FILES['product_image']['error'];
   $image_type = $_FILES['product_image']['type'];
    
   // create array variable to handle error
   $error = array();
   
   if(empty($product_title)){
    $error['product_title'] = " <span class='label label-danger'>Required!</span>";
   }
    
   if(empty($product_category_id)){
    $error['$product_category_id'] = " <span class='label label-danger'>Required!</span>";
   }    
    
   if(empty($product_price)){
    $error['product_price'] = " <span class='label label-danger'>Required!</span>";
   }else if(!is_numeric($product_price)){
    $error['product_price'] = " <span class='label label-danger'>product_price in number!</span>";
   }

   if(empty($product_quantity)){
    $error['product_quantity'] = " <span class='label label-danger'>Required!</span>";
   }else if(!is_numeric($product_quantity)){
    $error['product_quantity'] = " <span class='label label-danger'>product_quantity in number!</span>";
   }
    
   if(empty($serve_for)){
    $error['serve_for'] = " <span class='label label-danger'>Not choosen</span>";
   }   

   if(empty($product_description)){
    $error['product_description'] = " <span class='label label-danger'>Required!</span>";
   }
   
   // common image file extensions
   $allowedExts = array("gif", "jpeg", "jpg", "png");
   
   // get image file extension
   error_reporting(E_ERROR | E_PARSE);
   $extension = end(explode(".", $_FILES["product_image"]["name"]));
   
   if(!empty($product_image)){
    if(!(($image_type == "image/gif") || 
     ($image_type == "image/jpeg") || 
     ($image_type == "image/jpg") || 
     ($image_type == "image/x-png") ||
     ($image_type == "image/png") || 
     ($image_type == "image/pjpeg")) &&
     !(in_array($extension, $allowedExts))){
     
     $error['product_image'] = "*<span class='label label-danger'>Image type must jpg, jpeg, gif, or png!</span>";
    }
   }
   
     
   if(!empty($product_title) && !empty($product_category_id) && !empty($product_price) && is_numeric($product_price) &&
    !empty($serve_for) && !empty($product_description) && empty($error['product_image']) && !empty($product_quantity) && is_numeric($product_quantity)){
    
    if(!empty($product_image)){
     
     // create random image file name
     $string = '0123456789';
     $file = preg_replace("/\s+/", "_", $_FILES['product_image']['name']);
     $function = new functions;
     $product_image = $function->get_random_string($string, 4)."-".date("Y-m-d").".".$extension;
    
     // delete previous image
     $delete = unlink("$previous_product_image");
     
     // upload new image
     $upload = move_uploaded_file($_FILES['product_image']['tmp_name'], 'upload/images/'.product_image);
   
     // updating all data
     $sql_query = "UPDATE products 
       SET product_title = ? , product_category_id = ?, product_price = ?, Serve_for = ?, product_image = ?, product_description = ?, product_quantity = ? 
       WHERE product_id = ?";
     
     $upload_image = 'upload/images/'.product_image;
     $stmt = $connect->stmt_init();
     if($stmt->prepare($sql_query)) { 
      // Bind your variables to replace the ?s
      $stmt->bind_param('ssssssss', 
         $product_title, 
         $product_category_id, 
         $product_price, 
         $serve_for, 
         $upload_image,
         $product_description,
         $product_quantity,
         $ID);
      // Execute query
      $stmt->execute();
      // store result 
      $update_result = $stmt->store_result();
      $stmt->close();
     }
    }else{
     
     // updating all data except image file
     $sql_query = "UPDATE products 
       SET product_title = ? , product_category_id = ?, 
       product_price = ?, Serve_for = ?, product_description = ?, product_quantity = ? 
       WHERE product_id = ?";
       
     $stmt = $connect->stmt_init();
     if($stmt->prepare($sql_query)) { 
      // Bind your variables to replace the ?s
      $stmt->bind_param('sssssss', 
         $product_title, 
         $product_category_id, 
         $product_price, 
         $serve_for, 
         $product_description,
         $product_quantity,
         $ID);
      // Execute query
      $stmt->execute();
      // store result 
      $update_result = $stmt->store_result();
      $stmt->close();
     }
    }
     
    // check update result
    if($update_result){
     $error['update_data'] = " <span class='label label-primary'>Success update</span>";
    }else{
     $error['update_data'] = " <span class='label label-danger'>failed update</span>";
    }
   }
   
  }
  
  // create array variable to store previous data
  $data = array();
   
  $sql_query = "SELECT * FROM products WHERE product_id = ?";
   
  $stmt = $connect->stmt_init();
  if($stmt->prepare($sql_query)) { 
   // Bind your variables to replace the ?s
   $stmt->bind_param('s', $ID);
   // Execute query
   $stmt->execute();
   // store result 
   $stmt->store_result();
   $stmt->bind_result($data['product_id'], 
     $data['product_title'], 
     $data['product_category_id'], 
     $data['product_price'], 
     $data['Serve_for'], 
     $data['product_image'],
     $data['product_description'],
     $data['product_quantity']
     );
   $stmt->fetch();
   $stmt->close();
  }
  
   
 ?>
 <div class="col-md-12">
 <h1>Edit Menu <?php echo isset($error['update_data']) ? $error['update_data'] : '';?></h1>
 <hr />
 </div>
 
 <form method="post" enctype="multipart/form-data">
 <div class="col-md-9">
  <div class="col-md-12">
   <label>Menu Name :</label><?php echo isset($error['product_title']) ? $error['product_title'] : '';?>
   <input type="text" name="product_title" class="form-control" value="<?php echo $data['product_title']; ?>"/>
  </div>

  <div class="col-md-3">
     <br>
     <label>product_price (<?php echo $currency;?>) :</label><?php echo isset($error['product_price']) ? $error['product_price'] : '';?>
  <input type="text" name="product_price" class="form-control" value="<?php echo $data['product_price'];?>"/>
  <br/>

  <label>Stock :</label><?php echo isset($error['product_quantity']) ? $error['product_quantity'] : '';?>
  <input type="text" name="product_quantity" class="form-control" value="<?php echo $data['product_quantity'];?>"/>
  <br/>

     <label>Status :</label><?php echo isset($error['serve_for']) ? $error['serve_for'] : '';?>
  <select name="serve_for" class="form-control">
   <option>Available</option>
   <option>Sold Out</option>
  </select>
  <br/>
     <label>Category :</label><?php echo isset($error['product_category_id']) ? $error['product_category_id'] : '';?>
  <select name="product_category_id" class="form-control">
   <?php while($stmt_category->fetch()){ 
    if($category_data['cat_id'] == $data['cat_id']){?>
     <option value="<?php echo $category_data['cat_id']; ?>" selected="<?php echo $data['cat_id']; ?>" ><?php echo $category_data['cat_title']; ?></option>
    <?php }else{ ?>
     <option value="<?php echo $category_data['cat_id']; ?>" ><?php echo $category_data['cat_title']; ?></option>
    <?php }} ?>
  </select>
  
     <br/>
  <label>Image :</label><?php echo isset($error['product_image']) ? $error['product_image'] : '';?>
  <input type="file" name="product_image" id="product_image"/><br />
  <img src="<?php echo $data['product_image']; ?>" width="210" height="160"/>
  </div>

  <div class="col-md-9">
  <br>
  <label>product_description :</label><?php echo isset($error['product_description']) ? $error['product_description'] : '';?>
  <textarea name="product_description" id="product_description" class="form-control" rows="16"><?php echo $data['product_description']; ?></textarea>
  <script type="text/javascript" src="css/js/ckeditor/ckeditor.js"></script>
  <script type="text/javascript">                        
            CKEDITOR.replace( 'product_description' );
        </script>
  </div>
 </div>
  
 <div class="col-md-3">
 <br/>
  <div class="panel panel-default">
   <div class="panel-heading">Add</div>
    <div class="panel-body">
     <input type="submit" class="btn-primary btn" value="Update" name="btnEdit" />
    </div>
  </div>
 </div>
 </form>
 <div class="separator"> </div>
</div>

<?php 
 $stmt_category->close();
 include_once('includes/close_database.php'); ?>