Base Classes | Qt 6.12
Description: Base classes are used in purchasing demo to enable cross-platform for Android and iOS.

- Qt 6.12
- Base Classes
- Qt 6.12.0 Reference Documentation

# Base Classes

## Classes

Class | Description
--- | ---
InAppProduct | A product registered in the store.
InAppStore | Main entry point for managing in-app purchases.
InAppTransaction | Contains information about a transaction in the external app store.
InAppPurchaseBackend | Communicates with the external store.

## InAppProduct

InAppProduct encapsulates a product in the external store after it has been registered in InAppStore and confirmed to exist. It has an identifier which matches the identifier of the product in the external store, it has a price which is retrieved from the external store, and it has a product type.

The product type can be `Consumable` or `Unlockable`. Consumable products can be purchased any number of times as long as each transaction is finalized explicitly by the application. Unlockable types can only be purchased once.

InAppProduct has 5 returnable variables `price`, `title`, `description` `identifier` and `productType`. All return a QString except productType.

ProductType is an enum type and returns `0` if it is Consumable and `1` if Unlockable.

     enum ProductType
     {
        Consumable,
        Unlockable
     };

Check out the derived classes `AndroidInAppProduct` for Android and `IosInAppProduct` for iOS.

## InAppStore

The main entry point for managing in-app purchases. It is the base class for `AndroidInAppProduct` and `IosInAppProduct`.

InAppStore is used for managing in-app purchases in the application in a cross-platform way. Depending on the compiler, InAppStore checks what platform is available using `Macros`.

     void InAppStore::setupBackend()
     {
        #ifdef Q_OS_ANDROID
        d->backend = new AndroidInAppPurchaseBackend;
        #endif

        #ifdef Q_OS_IOS
        d->backend = new IosInAppPurchaseBackend;
        #endif

        d->backend->setStore(this);

        ...

### Initializing the store

Upon going to the store page in the demo, InAppStore connects all signals to related slots in setupBackend() function. Then uses the registerProduct() function to register product ID and productType of each product registered in the external store to a QHash registeredProducts.

Registering a product is asynchronous, and will at some point yield productRegistered() signals when its found from external store.

     void InAppStore::registerProduct(InAppProduct *product)
     {
        d->registeredProducts[product->identifier()] = product;
        emit productRegistered(product);
     }

### Completing a purchase

Once the items have been successfully registered in the store, The user can purchase them by pressing on of the products on the apps store page. QML will call product.purchase() function in AndroidInAppProduct or `IosInAppProduct` which will open the external store's purchasing flow.

When a purchase has been completed regardless of success, the transactionRedy signal will be sent to `InAppProductQmlType`, to notify QML to start finalize the transaction.

### Restoring purchases

In the demo unlockable purchases will be saved on the apps storage. By clearing the storage the user will lose the unlockable purchase and it cannot be purchased again, as according to the external store it is already owned.

You can use the `restore purchases` button in the apps store page to restore your unlockable purchases. The restore purchases button calls the restorePurchases() function and will check the external store for already owned purchases. It emits the transactionRedy() signal to finalize and restore the purchase.

InAppStore has no derived classes.

## InAppTransaction

InAppTransaction contains information about a transaction in the external app store and is usually provided as a result of calling InAppProduct::purchase(). When the purchase flow has been completed by the user (confirming the purchase, for instance by entering their password), the InAppStore instance containing the product will emit a InAppStore::transactionReady() signal with data about the transaction.

The status() function provides information on if the transaction was successful or not. If it was successful, then the application should take appropriate action. When the necessary action has been performed, finalize() should be called. The finalize() function should be called regardless of the status of the transaction.

Check out the derived classes `AndroidInAppTransaction` for android and `IosInAppTransaction` for iOS.

## InAppPurchaseBackend

`InAppPurchaseBackend` is used to create derived class for `AndroidInAppPurchaseBackend` and `IosInAppPurchaseBackend`.