ValidationError when sparse updating a Payment trying to specify new LinkedTxn lines - intuit-partner-platform

Question

I am trying to perform a sparse update on a QuickBooks Online Payment object using the .NET SDK. For some reason as soon as I try to specify a <Line> element in the update request, I get a ValidationError requiring a CustomerRef.
Request:
<?xml version="1.0"?>
<Payment xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" sparse="true" xmlns="http://schema.intuit.com/finance/v3">
<Id>1060</Id>
<SyncToken>3</SyncToken>
<TxnDate>2014-11-25</TxnDate>
<PrivateNote />
<Line>
<Amount>390.0000</Amount>
<LinkedTxn>
<TxnId>1308</TxnId>
<TxnType>Invoice</TxnType>
</LinkedTxn>
</Line>
<TotalAmt>390.0000</TotalAmt>
</Payment>
Response:
{"Fault": {
"Error": [{
"Message":"Required param missing, need to supply the required value for the API",
"Detail":"Required parameter CustomerRef is missing in the request",
"code":"2020",
"element":"Payment"}],
"type":"ValidationFault"},
"time":"2015-01-20T07:20:15.191-08:00"}
I thought a sparse update meant that anything you did not specify stayed the same as the original entity. I can't see anything that says one way or the other in the documentation. Do I need to fetch the CustomerRef from the current entity to feed it back to the API and keep it happy, or am I just doing something wrong?

Answer 1

Although this is Sparse update but I believe the customerref is required, as a 'validation check for Customer' is needed when you send the Update request. This check is needed to verify that CustomerRef for Updated payment is same as the Invoice's CustomerRef. So, you should send it in your request.