Stripe: accessing transfers after a connected account gets payed out - stripe-payments

Question

I need to figure out which transfers are part of custom connected account payouts!
I'm using Stripe and creating transfers to pass money from my platform to different custom connected accounts. One custom connected account might receive 300+ different transfers with amounts. When Stripe pays out to the connected account, I receive a couple of webhooks (payout.created, payout.paid) and these contain a balance transaction id, which looks like it is the only id that can be used to fetch any transfers from that payout, but how? or is this not how you would do it?
FYI - I need a way to update each connected account transfer to show they are now paid, instead of pending...

Answer 1

When you have a payout ID(po_xxx), you can filter balance transactions on the connected account by that ID — this returns all the transactions that were paid out in that payout object: https://stripe.com/docs/api/balance/balance_history#balance_history-payout
From these transactions, you can find the source of the transaction : https://stripe.com/docs/api/balance/balance_transaction#balance_transaction_object-source
When you make a transfer to a connected account, a py_xxx object is created on the connected account, representing the payment, and this would be the source of the balance transactions. This payment object has a source_transfer field which is the ID of the transfer(tr_xxx).
Putting this all together, if you want to know which transfers were paid out in a given payout, you would combine a list payout call with the expanding objects feature of the API to retrieve all the information at once. It's something like this in Node:
await stripe.balance.listTransactions({
payout: "po_xxx",
expand : ["data.source.source_transfer"]
}, {stripe_account : "{CONNECTED_ACCOUNT_ID"}).autoPagingEach(function(transaction) {
console.log(transaction.source.source_transfer.id); // the tr_xx transfer object
});