I am implementing in-app billing in my app to unlock premium features. The in-app billing sets up correctly. Everything seems fine except the 'developer payload' thing.
The sample app says
/*
* TODO: verify that the developer payload of the purchase is correct. It will be
* the same one that you sent when initiating the purchase.
*
* WARNING: Locally generating a random string when starting a purchase and
* verifying it here might seem like a good approach, but this will fail in the
* case where the user purchases an item on one device and then uses your app on
* a different device, because on the other device you will not have access to the
* random string you originally generated.
*
* So a good developer payload has these characteristics:
*
* 1. If two different users purchase an item, the payload is different between them,
* so that one user's purchase can't be replayed to another user.
*
* 2. The payload must be such that you can verify it even when the app wasn't the
* one who initiated the purchase flow (so that items purchased by the user on
* one device work on other devices owned by the user).
*
* Using your own server to store and verify developer payloads across app
* installations is recommended.
*/
See Question&Answers more detail:osThe sample app uses an empty string as developer payload. My question is what string to use as a developer payload? Can I use the user's primary email ID?