Callbacks & Results¶

In this guide

The two callback interfaces the SDK uses, and the fields on the result and error objects they hand back.

The SDK uses callbacks so the host app receives results on the main thread.

You are already on the main thread

Callbacks are delivered on the main thread, so you can update UI directly without posting back to a handler.

PaymentCallback¶

Used by checkout() and payWithCard().

interface PaymentCallback {
    fun onSuccess(result: PaymentResult)
    fun onFailure(error: PaymentError)
    fun onCancelled()
}

Exactly one method is called for each payment attempt.

OperationCallback¶

Used by status, capture, void, refund, merchant transactions, recurring transactions, and recurring charges.

interface OperationCallback<T> {
    fun onSuccess(result: T)
    fun onFailure(error: PaymentError)
}

Transport success is not payment success

onSuccess means the request completed at the transport layer. Always inspect the business fields such as status, result, or paymentStatus to know the real outcome.

Shared Helper¶

You can create a small helper to avoid repeating error handling.

private fun <T> operationCallback(onSuccess: (T) -> Unit) =
    object : OperationCallback<T> {
        override fun onSuccess(result: T) = onSuccess(result)

        override fun onFailure(error: PaymentError) {
            // Log error.code and show error.message when appropriate.
        }
    }

PaymentResult¶

sessionId: Checkout session or payment id. Use it as paymentId for later operations.
transactionId: Gateway transaction id, for reconciliation and records.
orderId: Merchant order id.
amount: Paid amount.
currency: Payment currency.
status: Gateway status.

PaymentError¶

code: Stable ErrorCode enum for programmatic handling — see Error Handling.
message: User or support-facing message.
details: Optional additional gateway or diagnostic detail.

Handle by code, display message

Branch your logic on code (stable), and show message to users. Log details for diagnostics — but never log full card data.