Shopify has a CARTS api but it is read-only. I am trying to find a way to manipulate the line_item’s line_price or price attribute. Shopify support has directed me here for an answer.
Since there is no proper documentation on this any help would be appreciated.
Products have variants, and a line item has a product ID and a variant ID. A line item has a price too. And no matter how you access that item (using the Ajax API or the backend API) you cannot manipulate the price. If you want to change a price, you have to change the product’s variants price. That you do with the backend API and the product or variant calls.