Unable to use ProrationModesAndroid.DEFERRED when switching between offers on the same subscription product

[jwoodmansey]

Hi,

I am pretty sure this is not an issue with react-native-iap itself so I'm not opening an issue but looking for some advice.

We are trying to enable users to switch between different offers on the same subscription on Android, however we are unable to use ProrationModesAndroid.DEFERRED. Although I can't find this anywhere in Google's docs I am assuming this isn't supported since an error (DEVELOPER_ERROR (5)) it thrown when calling launchBillingFlow.

The issue with us using another method such as IMMEDIATE_WITHOUT_PRORATION is that we don't get informed that the user hasn't actually paid yet on the first server notification after switching to another offer on this subscription.

Essentially, the real-time developer notification wouldn't tell us that this first order wasn't really charged so our backend can't accurately track it.

How are others solving this situation?

[cervebar]

From our experience, I can confirm this for switching between base plans, DEFERRED for same base plans in one subscription in Billing library 5 is not supported by Google Android (and also not documented（＞д＜）).

When switching plans within the same subscription, only allowed proration modes are IMMEDIATE_AND_CHARGE_FULL_PRICE and IMMEDIATE_WITHOUT_PRORATION. Empirically tested.

You have 2 options:

1. use one of this options, for us it was IMMEDIATE_WITHOUT_PRORATION as it seems more close to DEFERRED mode regarding the examples in Android docs (the description of this mode itself, it is soooo confusing)

2. have 2 subscriptions for different time period and do not use base plans at all

I can expect it will be something similar for offers.

This discussion helped us: https://github.com/android/play-billing-samples/issues/549#issuecomment-1179330667.