I have looked for the solution for weeks, but I have not found any. It must be very trivial that I missed.
I'm adding a line item field in addition of the default unit price and quantity called "length" in the cart view and Order. I would like to get the new calculated line item total = price * quantity * length.
Solutions that I have found so far change the line item unit price, which is not desirable.
How can I do this?