payPal subscription transactions not showing up immediately

Question

I'm creating recurring payments through payPal subscriptions flow. On the frontend, I have a button auto-generated by payPal which redirects me to their domain. After that, it correctly returns the subscriptionID; after that, the frontend calls a backend API which should verify that subscriptionID, to check fields such "status" and so on. In this backend API, I need to store some "paymentID" (one per month, always unique, if the subscription is automatically renewed monthly), which I found to be called "transactionID" on payPal. I use the REST API GET /v1/billing/subscriptions/{id}/transactions, which should returns an object with a field transactions, which should be an array of transactions. The problem is that sometimes, just after the successful payment, this array is empty. If I wait some time (from few ms to minutes), then every subscription has it's own transactions, in the end.

Is there a way to fix this? Or, alternatively, is there something like transactions on the PayPal environment which can uniquely represents a specific payment?

Answer 1

When a subscription starts it takes time for the first transaction to be created.

Instead of querying the subscriptions API, create a webhook to be notified of PAYMENT.SALE.COMPLETEDevents. This will be useful for the initial transaction as well as all future transactions.