Google IAP get subscription details and store in DB

Question

I have an app that receives subscriptions from the user. I have implemented methods to receive payments and I can complete the transaction. When storing all the details in my database I can able to get details such as purchase id, purchase date and validity (returned P1Y for a 1-year subscription) but I also want to get the subscription end date is it possible? and how do I check if the user cancels the subscription or renews the subscription?

Answer 1

Revenue Cat:

Instead of using in_app_purchase I started using purchases_flutter (RevenueCat)

You can refer to their documentation for more information.

I currently use this method for in-app subscriptions.

Google Api:

I also managed to use google API to get the subscription details with the help of googleapis and googleapis_auth

IAP Helper class

Follow this documentation to complete the initial setup

Google API Credentials initialisation

  final _credentials = ServiceAccountCredentials.fromJson(r'''
        {
          "private_key_id": "keyid",
          "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIBADAN<private key>Sf\nbB9OjCOGt7ybJmDkMBe2U5Tq\n-----END PRIVATE KEY-----\n",
          "client_email": "mail",
          "client_id": "clientid",
          "type": "service_account"
        }
        ''');
  static const _scopes = [AndroidPublisherApi.androidpublisherScope];

Function to get Subscription details

 Future getSubData({@required String token , @required String productId})async{
    SubscriptionPurchase res;
    final httpClient = await clientViaServiceAccount(_credentials, _scopes);
    try {
      final pubApi = AndroidPublisherApi(httpClient);
      res = await pubApi.purchases.subscriptions.get('com.yourcompany.package', productId, token);
    } finally {
      httpClient.close();
    }
    return res;
  }

Delivering the product

_deliverProduct({@required PurchaseDetails purchaseDetails})async{
     await iap.completePurchase(purchaseDetails);
     final firestore.DocumentReference userDocReference = firebase.doc("Users/$_id/userdata/data");
     final firestore.CollectionReference historyDocReference = firebase.collection("Users/$_id/history/");
     final SubscriptionPurchase  apiRes = await getSubData(token:purchaseDetails.billingClientPurchase.purchaseToken,productId:purchaseDetails.productID);
     var data = {
       "TXN ID": purchaseDetails.billingClientPurchase.purchaseToken,
       "Order ID":purchaseDetails.billingClientPurchase.orderId,
       "Product ID":purchaseDetails.productID,
       "TXN Date": firestore.Timestamp.fromMillisecondsSinceEpoch(int.parse(purchaseDetails.transactionDate)),
       "Subscribed":true,
       "Start Date":firestore.Timestamp.fromMillisecondsSinceEpoch(int.parse(apiRes.startTimeMillis)),
       "Expiry Date": firestore.Timestamp.fromMillisecondsSinceEpoch(int.parse(apiRes.expiryTimeMillis)),
       "Payment Status": apiRes.paymentState,
       "isFreeTrail": (apiRes.paymentState==1)?false:true,
       "acknowledgementState":apiRes.acknowledgementState
     };
    await userDocReference.set({"Subscription":data,"Sub_Raw":apiRes.toJson()},firestore.SetOptions(merge: true)); //set to main user
    await historyDocReference.doc('${purchaseDetails.billingClientPurchase.purchaseToken}').set(data); //put in purchase history
  }

Now you can check if the user is subscribed or not from your firstore BD

This method may provide temporary FIX (Google PlayStore only) but I do not recommend this method as it contains a lot of security issues.

Note: Google only provides 200K API call's per day avoid calling API to check for subscription repeatedly.

Note: Google API method only works with in_app_purchase: ^0.5.2

Note: Google API method only works for Android and doesn't work for IOS.

Other Alternates

You can write your own server-side code in node.js/cloud firestore and you can achieve the same.

Ref : Cook book in_app_purchase

Disclaimer

I do not receive any incentive/payment from revenuecat for mentioning their product in this answer.