Purchase invoices need at least one line item to represent the transaction and how it should be coded.
The purchase invoice line endpoint looks like:
purchaseInvoices({p_id})/purchaseInvoiceLines
Where {p_id} represents the ID (a GUID) returned from the purchase invoice create request.
Acceptable types are noted below, and should be passed in the request body for creating a new purchase invoice line. Choose the correct line type for the transaction you are working with (inventory, non-inventory, etc). Note that the required element of a line may change depending on the type of line chosen.
Comment
Account
Item
Resource
Value
Fixed Asset
Charge
One of these values is required for the lineType parameter.
"lineType": "Account"