This API allows you to create new invoices and modify existing ones. Whether a new object is create or modified is dependant on the orderNumber value:
- If the orderNumber is left blank, a new invoice will be created and an orderNumber will automatically be generated.
- If the orderNumber is present, the existing invoice with that orderNumber will be retrieved. If there is no match, a new invoice will be created with the orderNumber provided.
You can send multiple invoice line items by incrementing the count value at the end of each field. Example, send fields "itemSKU1" and "itemSKU2" would create two line items.
The invoice amount and amount due fields are computed value. The amount is based on the item totals + taxes + shipping + tips - discounts, and the amount due is the calculated amount minus transactions successfully applied to the invoice.