Google play billing - How to check user already purchased subscription for 2nd opening the app?

Question

I followed the guide from Google developer document: https://developer.android.com/google/play/billing/integrate?hl=vi

Finished step process Purchase Flow, and handle Purchase result and handle Acknowledge Purchase Response. In this steps, I can determine user purchased success or not.

And currently I don't have any back-end for doing next step of the guide : https://developer.android.com/google/play/billing/backend?hl=vi

When running the app again, how can I determine user had purchased subscription already (without process a purchase flow again ) ? And how to determine user subscription when they changed device ?

Answer 1

it can be done with queryPurchasesAsync

    void QueryPurchase(){
        QueryPurchasesParams queryPurchasesParams = QueryPurchasesParams.newBuilder().setProductType(BillingClient.ProductType.SUBS).build();
        billingClient.queryPurchasesAsync(queryPurchasesParams, new PurchasesResponseListener() {
            @Override
            public void onQueryPurchasesResponse(@NonNull BillingResult billingResult, @NonNull List<Purchase> list) {
                if(list==null){
                    return;
                }
                Log.d(TAG, "onQueryPurchasesResponse, list.size="+String.valueOf(list.size()));
                for(Purchase purchase: list){
                    boolean bIsAutoRenewing = purchase.isAutoRenewing();
                    Log.d(TAG, "bIsAutoRenewing = "+String.valueOf(bIsAutoRenewing));
                }
            }
        });
    }

then it can be determine by bIsAutoRenewing