implement affirm example screen (#1816)

Co-authored-by: Remon <[email protected]>

example/lib/screens/regional_payment_methods/affirm_screen.dart

@@ -0,0 +1,87 @@
+import 'dart:convert';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_stripe/flutter_stripe.dart';
+import 'package:http/http.dart' as http;
+import 'package:stripe_example/widgets/example_scaffold.dart';
+import 'package:stripe_example/widgets/loading_button.dart';
+
+import '../../config.dart';
+
+class AffirmScreen extends StatelessWidget {
+  const AffirmScreen({Key? key}) : super(key: key);
+
+  Future<Map<String, dynamic>> _createPaymentIntent() async {
+    final url = Uri.parse('$kApiUrl/create-payment-intent');
+    final response = await http.post(
+      url,
+      headers: {
+        'Content-Type': 'application/json',
+      },
+      body: json.encode({
+        'currency': 'usd',
+        'payment_method_types': ['affirm'],
+      }),
+    );
+
+    print('blaat ${json.decode(response.body)}');
+    return json.decode(response.body);
+  }
+
+  Future<void> _pay(BuildContext context) async {
+    // Precondition:
+    //Make sure to have set a custom URI scheme in your app and add it to Stripe SDK
+    // see file main.dart in this example app.
+    // 1. on the backend create a payment intent for payment method and save the
+    // client secret.
+    final result = await _createPaymentIntent();
+    final clientSecret = await result['clientSecret'];
+
+    // 2. use the client secret to confirm the payment and handle the result.
+    try {
+      await Stripe.instance.confirmPayment(
+        paymentIntentClientSecret: clientSecret,
+        data:
+            PaymentMethodParams.affirm(paymentMethodData: PaymentMethodData()),
+      );
+
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(
+          content: Text('Payment succesfully completed'),
+        ),
+      );
+    } on Exception catch (e) {
+      if (e is StripeException) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(
+            content: Text(
+                'Error from Stripe: ${e.error.localizedMessage ?? e.error.code}'),
+          ),
+        );
+      } else {
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(
+            content: Text('Unforeseen error: ${e}'),
+          ),
+        );
+      }
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return ExampleScaffold(
+      title: 'Affirm',
+      tags: ['Payment method'],
+      padding: EdgeInsets.all(16),
+      children: [
+        LoadingButton(
+          onPressed: () async {
+            await _pay(context);
+          },
+          text: 'Pay',
+        ),
+      ],
+    );
+  }
+}

example/lib/screens/screens.dart

@@ -5,6 +5,7 @@ import 'package:stripe_example/screens/payment_sheet/payment_element/payment_ele
 import 'package:stripe_example/screens/payment_sheet/payment_sheet_deffered_screen.dart';
 import 'package:stripe_example/screens/payment_sheet/payment_sheet_screen.dart';
 import 'package:stripe_example/screens/payment_sheet/payment_sheet_screen_custom_flow.dart';
+import 'package:stripe_example/screens/regional_payment_methods/affirm_screen.dart';
 import 'package:stripe_example/screens/regional_payment_methods/ali_pay_screen.dart';
 import 'package:stripe_example/screens/regional_payment_methods/aubecs_debit.dart';
 import 'package:stripe_example/screens/regional_payment_methods/cash_app_screen.dart';
@@ -237,6 +238,12 @@ class Example extends StatelessWidget {
         builder: (context) => AliPayScreen(),
         platformsSupported: [DevicePlatform.android, DevicePlatform.ios],
       ),
+      Example(
+        title: 'Affirm',
+        leading: SizedBox(),
+        builder: (context) => AffirmScreen(),
+        platformsSupported: [DevicePlatform.android, DevicePlatform.ios],
+      ),
       Example(
         title: 'Cash app Pay',
         builder: (context) => CashAppScreen(),

packages/stripe_platform_interface/lib/src/models/payment_methods.dart

@@ -55,7 +55,7 @@ class PaymentMethod with _$PaymentMethod {
 
     @JsonKey(name: 'Upi') required Upi upi,
 
-    /// Containing additional data in case paymentmethod type is UPI.
+    /// Containing additional data in case paymentmethod type is Us bank account.
     @JsonKey(name: 'USBankAccount') required UsBankAccount usBankAccount,
 
     /// Id related to the customer to which this paymentmethod has been saved.