override/controllers/admin/AdminImportcontroller.php

public function supplyOrdersDetailsImport()
    {
        // opens CSV & sets locale
        $this->receiveTab();
        $handle = $this->openCsvFile();
        AdminImportController::setLocale();

        $products = array();
        $reset = true;
        // main loop, for each supply orders details to import
        for ($current_line = 0; $line = fgetcsv($handle, MAX_LINE_SIZE, $this->separator); ++$current_line)
        {
            // if convert requested
            if (Tools::getValue('convert'))
                $line = $this->utf8EncodeArray($line);
            $info = AdminImportController::getMaskedRow($line);

            // sets default values if needed
            AdminImportController::setDefaultValues($info);

            // gets the supply order
            if (array_key_exists('supply_order_reference', $info) && pSQL($info['supply_order_reference']) && SupplyOrder::exists(pSQL($info['supply_order_reference'])))
                $supply_order = SupplyOrder::getSupplyOrderByReference(pSQL($info['supply_order_reference']));
            else
                $this->errors[] = sprintf($this->l('Supply Order (%s) could not be loaded (at line %d).'), (int)$info['supply_order_reference'], $current_line + 1);

            if (empty($this->errors))
            {
                // sets parameters
                $id_product = (int)$info['id_product'];
                if (!$info['id_product_attribute'])
                    $info['id_product_attribute'] = 0;
                $id_product_attribute = (int)$info['id_product_attribute'];
                $unit_price_te = (float)$info['unit_price_te'];
                $quantity_expected = (int)$info['quantity_expected'];
                $discount_rate = (float)$info['discount_rate'];
                $tax_rate = (float)$info['tax_rate'];

                // checks if one product is there only once
                if (isset($product['id_product']))
                {
                    if ($product['id_product'] == $id_product && $product['id_product_attribute']== $id_product_attribute)
                        $this->errors[] = sprintf($this->l('Product (%d/%D) cannot be added twice (at line %d).'), $id_product,
                            $id_product_attribute, $current_line + 1);
                    else{
                        $product['id_product'] = $id_product;
                        $product['id_product_attribute']= $id_product_attribute;
                    }

                }
                else
                    $product['id_product'] = 0;

                // checks parameters
                if (false === ($supplier_reference = ProductSupplier::getProductSupplierReference($id_product, $id_product_attribute, $supply_order->id_supplier)))
                    $this->errors[] = sprintf($this->l('Product (%d/%d) is not available for this order (at line %d).'), $id_product,
                        $id_product_attribute, $current_line + 1);
                if ($unit_price_te < 0)
                    $this->errors[] = sprintf($this->l('Unit Price (tax excl.) (%d) is not valid (at line %d).'), $unit_price_te, $current_line + 1);
                if ($quantity_expected < 0)
                    $this->errors[] = sprintf($this->l('Quantity Expected (%d) is not valid (at line %d).'), $quantity_expected, $current_line + 1);
                if ($discount_rate < 0 || $discount_rate > 100)
                $this->errors[] = sprintf($this->l('Discount rate (%d) is not valid (at line %d). %s.'), $discount_rate,
                                           $current_line + 1, $this->l('Format: between 0 and 100'));
                if ($tax_rate < 0 || $tax_rate > 100)
                $this->errors[] = sprintf($this->l('Quantity Expected (%d) is not valid (at line %d).'), $tax_rate,
                                           $current_line + 1, $this->l('Format: between 0 and 100'));

                // if no errors, sets supply order details
                if (empty($this->errors))
                {
                    // resets order if needed
                    if ($reset)
                    {
                        $supply_order->resetProducts();
                        $reset = false;
                    }

                    // creates new product
                    $supply_order_detail = new SupplyOrderDetail();
                    AdminImportController::arrayWalk($info, array('AdminImportController', 'fillInfo'), $supply_order_detail);

                    // sets parameters
                    $supply_order_detail->id_supply_order = $supply_order->id;
                    $currency = new Currency($supply_order->id_ref_currency);
                    $supply_order_detail->id_currency = $currency->id;
                    $supply_order_detail->exchange_rate = $currency->conversion_rate;
                    $supply_order_detail->supplier_reference = $supplier_reference;
                    $supply_order_detail->name = Product::getProductName($id_product, $id_product_attribute, $supply_order->id_lang);

                    // gets ean13 / ref / upc
                    $query = new DbQuery();
                    $query->select('
                        IFNULL(pa.reference, IFNULL(p.reference, \'\')) as reference,
                        IFNULL(pa.ean13, IFNULL(p.ean13, \'\')) as ean13,
                        IFNULL(pa.upc, IFNULL(p.upc, \'\')) as upc
                    ');
                    $query->from('product', 'p');
                    $query->leftJoin('product_attribute', 'pa', 'pa.id_product = p.id_product AND id_product_attribute = '.(int)$id_product_attribute);
                    $query->where('p.id_product = '.(int)$id_product);
                    $query->where('p.is_virtual = 0 AND p.cache_is_pack = 0');
                    $res = Db::getInstance(_PS_USE_SQL_SLAVE_)->executeS($query);
                    $product_infos = $res['0'];

                    $supply_order_detail->reference = $product_infos['reference'];
                    $supply_order_detail->ean13 = $product_infos['ean13'];
                    $supply_order_detail->upc = $product_infos['upc'];

                    $supply_order_detail->add();
                    $supply_order->update();
                    unset($supply_order_detail);

                }
            }
        }

        // closes
        $this->closeCsvFile($handle);
    }