Получить значение из объекта класса

ввод команды

print_r($file_array);

выводит

stdClass Object ( [line_item_id] => 56 
    [order_id] => 51 
    [type] => product 
    [line_item_label] => gbo140317 
    [quantity] => 1.00 
    [created] => 1491996947 
    [changed] => 1491996954 
    [data] => Array ( 
        [context] => Array ( 
            [product_ids] => Array ( [0] => 1 ) 
            [add_to_cart_combine] => 1 
            [show_single_product_attributes] => 
            [display_path] => node/4897 
            [entity] => Array ( 
                [entity_type] => node 
                [entity_id] => 4897 
                [product_reference_field_name] => field_prod 
            )
        ) 
    )
)

подскажите как достать entity_id