title: Prestashop 1.6 Advanced Stock management
body: <p>i'm currently working on a PS 1.6 shop which uses advanced stock management.</p>
  <p>Here is the issue we're in trouble with :</p>
  <ul>
  <li>an order has 1 product (let's say with 1 quantity) which has <strong>negative stock</strong> (real quantity)</li>
  <li>when this order is shipped, the product stock (let's say <strong>-10</strong>) goes from +1 instead of -1 (in this case <strong>from -10 to -9 instead of -11</strong>)...</li>
  </ul>
  <p>I've tried several ways to correct like</p>
  <pre><code> if(StockAvailable::dependsOnStock($product['id_product'], (int)$order-&gt;id_shop)) {
              StockAvailable::updateQuantity($product['product_id'], $product['product_attribute_id'], (int)$product['product_quantity'], $order-&gt;id_shop);
          }
  </code></pre>
  <p>but nothing changed... In ps_stock_available, quantity is not good (and I don't want to correct it by a simple SQL request which could have massive side effects)</p>
  <p>Has someone ever experienced this ?</p>
  <p>Thanks in advance ;)</p>