class PaymentRequest { PaymentRequest(this.address, this.amount, {this.scheme}); factory PaymentRequest.fromUri(Uri uri) { var address = ""; var amount = ""; var scheme = ""; if (uri != null) { address = uri.path; amount = uri.queryParameters['tx_amount'] ?? uri.queryParameters['amount'] ?? ""; scheme = uri.scheme; } return PaymentRequest(address, amount, scheme: scheme); } final String address; final String amount; final String scheme; }