Android in-app purchases

Godot engine has integrated GooglePaymentsV3 module with which we can implement in-app purchases in our game.

The Godot engine demo project repository has an android-iap example project. It includes a gdscript interface for android IAP.

Check the repository here https://github.com/godotengine/godot-demo-projects

Find the iap.gd script in

godot-demo-projects/misc/android_iap

Add it to the Autoload list and name it as IAP so that we can reference it anywhere in the game.

Getting the product details

When starting our game, we will need to get the item details from Google such as the product price, description and localized price string etc.

#First listen to the sku details update callback
IAP.connect("sku_details_complete",self,"sku_details_complete")

#Then ask google the details for these items
IAP.sku_details_query(["pid1","pid2"]) #pid1 and pid2 are our product ids entered in Googleplay dashboard


#This will be called when sku details are retrieved successfully
func sku_details_complete():
    print(IAP.sku_details) #This will print the details as JSON format, refer the format in iap.gd
    print(IAP.sku_details["pid1"].price) #print formatted localized price

We can use the IAP details to display the title, price and/or description on our shop scene.

Check if user purchased an item

When starting our game, we can check if the user has purchased any product. YOU SHOULD DO THIS ONLY AFTER 2/3 SECONDS AFTER YOUR GAME IS LOADED. If we do this as the first thing when the game is launched, IAP might not be initialized and our game will crash on start.

#Add a listener first
IAP.connect("has_purchased",self,"iap_has_purchased")
IAP.request_purchased() #Ask Google for all purchased items

#This will call for each and every user purchased products
func iap_has_purchased(item_name):
    print(item_name) #print the name of purchased items

Google IAP policy says the game should restore the user’s purchases if the user replaces their phone or reinstalls the same app. We can use the above code to check what products the user has purchased and we can make our game respond accordingly.

Simple Purchase

We can put this purchase logic on a product’s buy button.

#First listen for purchase_success callback
IAP.connect("purchase_success",self,"purchase_success_callback")

#Then call purchase like this
IAP.purchase("pid1") #replace pid1 with your product id
IAP.purchase("pid2") #replace pid2 with your another product id

#This function will be called when the purchase is a success
func purchase_success_callback(item):
    print(item + " has purchased")

We can also implement other signals for the purchase flow and improve the user experience as you needed.

purchase_fail - When the purchase is failed due to any reason

purchase_cancel - When the user cancels the purchase

purchase_owned - When the user already bought the product earlier

Consumables and Non-Consumables

There are two types of products - consumables and non-consumables. Consumables are purchased and used, for eg: healing potions which can be purchased again and again. Non-consumables are one time purchases, for eg: Level packs.

Google doesn’t have this separation in their dashboard. If our product is a consumable, and if a user has purchased it, it will not be available for purchase until it is consumed. So we should call the consume method for our consumables and don’t call consume for your non-consumables.

IAP.connnect("consume_success",self,"on_consume_success")
IAP.consume("pid")

func on_consume_success(item):
    print(item + " consumed")

If our game has only consumables, we don’t have to do this. We can set it to consume the item automatically after a purchase.

IAP.set_auto_consume(true)

If our game has only non-consumables, we can

IAP.set_auto_consume(false)

We should set the auto consume value only once when the game starts.

Testing

If we add a gmail id as a tester in Google dashboard, that tester can purchase items and they will not be charged. Another way to test IAP is using redeem codes generated by us for our game because the purchase flow is the same.

Third way of testing is in development side. If we put the product ids as shown below, we will get a static fixed response according to the product id. This is a quick way of testing things before going to the dashboard.

  • android.test.purchased
  • android.test.canceled
  • android.test.refunded
  • android.test.item_unavailable