Тоже нужна была такая возможность.
Сделал так:
в файле admin\model\catalog\product.php строки:
// Start filter
$this->db->query("DELETE FROM " . DB_PREFIX . "product_to_value WHERE product_id = '" . (int)$product_id . "'");
if (isset($data['product_to_value_id'])) {
foreach ($data['product_to_value_id'] as $option_id => $value_id) {
$this->db->query("INSERT INTO " . DB_PREFIX . "product_to_value SET product_id = '" . (int)$product_id . "', option_id = '" . (int)$option_id . "', value_id = '" . (int)$value_id . "'");
}
}
// End filter изменил на:
// Start filter
$this->db->query("DELETE FROM " . DB_PREFIX . "product_to_value WHERE product_id = '" . (int)$product_id . "'");
if (isset($data['product_to_value_id'])) {
foreach ($data['product_to_value_id'] as $option_id => $value_arr) {
foreach($value_arr as $value_id) {
$this->db->query("INSERT INTO " . DB_PREFIX . "product_to_value SET product_id = '" . (int)$product_id . "', option_id = '" . (int)$option_id . "', value_id = '" . (int)$value_id . "'");
}
}
}
// End filter в файле admin\controller\catalog\filter.php строку:
$html .= '<select name="product_to_value_id[' . $option['option_id'] . ']">'; изменил на:
$html .= '<select multiple name="product_to_value_id[' . $option['option_id'] . '][]">';
