Server Side Integration

In order for a purchase to be considered successfully completed, the server needs to validate the purchase and update the user’s coins in the database.

For this to happen, we will configure a webhook on the RevenueCat dashboard that will send a POST request to our server every time a purchase is made.

Store product IDs in the .env file

The server must know what products are available for purchase, so we need to store the product IDs in the .env file.

PAYMENT_PRODUCT_50_COINS=biddo_app_coins_50
PAYMENT_PRODUCT_200_COINS=biddo_app_coins_200
PAYMENT_PRODUCT_500_COINS=biddo_app_coins_500

These product IDs are found in the RevenueCat dashboard, in the Products tab.

Only cases for 50, 200, and 500 coins are handled. If you have more products, you also need to check the src/config.ts file, where the PAYMENT_PRODUCTS array is defined.

These product IDs will be sent to the mobile app, in order for it to know what products are available for purchase.

If you have more products that offer the same amount of coins (e.g. 100 coins), you can add all the product IDs in the same value, separated by comma (,). For example:

PAYMENT_PRODUCT_200_COINS=biddo_app_coins_200_ios,biddo_app_coins_200_android

Configure RevenueCat Webhook

1. Go to the RevenueCat dashboard and select your app.

2. Go to the Integrations tab and click on the + Add Integration button.

3. Select Webhooks from the list of integrations.

4. You will be asked to add a few details about the webhook:

   • Name: Give the webhook a name that will help you identify it later.
   • URL: Add the URL of your server where the webhook will send the POST request.
   • Authorization: Add a secret key that will be used to authenticate the request on the server.
   • Environment: Select the environment where the webhook will be active (Sandbox or Production).

   An example of how the URL and the Authorization key should look like:

   URL: https://YOUR_SERVER_OR_YOUR_URL/payment/hook
   Authorization: YOUR_DESIRED_SECRET_KEY (Make sure you copy this)

If you want to test the webhook locally, you can use a tool like ngrok to create a tunnel to your local server.

5. The YOUR_DESIRED_SECRET_KEY value needs to be copied and added to the server’s .env file, as it will be used to authenticate the webhook requests.

This is how the field should be added to the .env file:

PAYMENT_AUTH_KEY=YOUR_DESIRED_SECRET_KEY

If you want to test the payment flow, please also have a look at the following tutorial, on RevenueCat.

On Android, your app will need to be accepted in the Play Store before you can test the in-app purchases. You can create a Closed testing track for this.