Problem in inserting data into many to many relationships using attach() function laravel

i have two tables (orders & products) and one pivot table (order_product). i have made many to many relationship b\w them using following code.

class Product extends Model{
 protected $fillable = ['name', 'price', 'is_iframe_product'];
  public function orders() {
      return $this->belongsToMany(Order::class);
}   }


class Order extends Model{
public $guaded = ['id'];
 protected $fillable = ['is_iframe_order','price', 'status', 'address_id', 'user_id'];
public function products () {
    return $this->belongsToMany(Product::class);
}     }

i am using following code to insert records in CheckoutController.php

 $Product = array('name' => $item['item_name'], "price" => $item['price'], "is_iframe_product" => "1");
      $saved = order()->products()->attach([$Product]);

but getting this error:

exception: "Symfony\Component\Debug\Exception\FatalThrowableError" file: "C:\wamp3\www\jewellery\jewellery\app\Http\Controllers\CheckoutController.php" line: 63 message: "Call to undefined function App\Http\Controllers\order()"

via Chebli Mohamed