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Subscription Checkout Integration Flutter Guide

This integration allows you to integrate with a Cashfree Subscription checkout in your app. The Flutter SDK is hosted on https://pub.dev/ you can get the sdk here. The example app is located here.

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Setting Up SDK

Our Flutter SDK supports Android SDK version 19 and above and iOS minimum deployment target of 11 and above. Open your project’s pubspec.yaml and add the following under dependencies: 
dependencies:
  flutter_cashfree_pg_sdk: ^2.2.7

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Step 1: Creating a Subscription

The first step in the Subscription Checkout integration is to create a subscription. You need to do this before any payment can be processed. You can add an endpoint to your server which creates this subscription and is used for communication with your frontend.
Subscription creation must happen from your backend (as this API uses your secret key). Please do not call this directly from your mobile application. You can use below-mentioned backend SDKs
Once you create subscription, you will get the subscription_id and subscription_session_id

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Step 2: Opening the Subscription Checkout Payment Page

Once the subscription is created, the next step is to open the payment page so the customer can make the payment. To complete the payment, we can follow the following steps:
  1. Enable Subscription flow flag in Android Manifest
  2. Create a CFSubscriptionSession object.
  3. Create a CFTheme object (Optional).
  4. Create a CFSubscriptionPayment object.
  5. Set payment callback.
  6. Initiate the payment using the payment object created from [step 3]
We go through these step by step below.

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Enable Subscription flow flag

Add the Below entry to your Android manifest file. If you don’t enable cashfree_subscription_flow_enable flag, SDK won’t provide a payment callback. It should be added inside application tag, not inside activity tag. 
  <application
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name">

      <meta-data
          android:name="cashfree_subscription_flow_enable"
          android:value="true"
          tools:replace="android:value"/>
  </application>

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Create a Subscription Session

This object contains essential information about the subscription, including the subscription session ID (subscription_session_id) and subscription ID (subscription_id) obtained from creation step. It also specifies the environment (sandbox or production). 
try {
    var subscriptionSession = CFSubscriptionSessionBuilder().setEnvironment(environment).setSubscriptionId(subscriptionId).setSubscriptionSessionId(subscriptionSessionId).build();
    return subsriptionSession;
} on CFException catch (e) {
    print(e.message);
}

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Customize Theme (Optional)

You can customize the appearance of the checkout screen using CFTheme. This step is optional but can help maintain consistency with your app’s design. You can set the NavigationBarBackgroundColor which will set the color for status bar & cashfree loader 
var theme = CFThemeBuilder()
          .setNavigationBarBackgroundColorColor("#ffffff")
          .setNavigationBarTextColor("#ffffff")
          .build();

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Create Subscription Payment Object

Use CFSubscriptionPaymentBuilder to create the payment object. This object accepts a CFSubscriptionSession, like the one created in the previous step. 
var cfSubscriptionCheckout = CFSubscriptionPaymentBuilder()
  .setSession(subscriptionSession!)
  .setTheme(theme)
  .build();

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Setup payment callback

You need to set up callback handlers to handle events after payment processing. This must be set before calling doPayment. 
void onSubscriptionVerify(String subscriptionId) {
    print("Verify Subscription ===> $subscriptionId");
 }

void onSubscriptionFailure(CFErrorResponse errorResponse, String data) {
    print("Failure in subscription flow");
}

var cfPaymentGatewayService = CFPaymentGatewayService();
@override
void initState() {
  super.initState();
  cfPaymentGatewayService.setCallback(onSubscriptionVerify, onSubscriptionFailure);
}

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Step 3: Sample Code

import 'package:flutter/material.dart';
import 'package:flutter_cashfree_pg_sdk/api/cferrorresponse/cferrorresponse.dart';
import 'package:flutter_cashfree_pg_sdk/api/cfpayment/cfsubscriptioncheckoutpayment.dart';
import 'package:flutter_cashfree_pg_sdk/api/cfpaymentgateway/cfpaymentgatewayservice.dart';
import 'package:flutter_cashfree_pg_sdk/api/cfsession/cfsubssession.dart';
import 'package:flutter_cashfree_pg_sdk/api/cftheme/cftheme.dart';
import 'package:flutter_cashfree_pg_sdk/utils/cfenums.dart';
import 'package:flutter_cashfree_pg_sdk/utils/cfexceptions.dart';

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {

  var cfPaymentGatewayService = CFPaymentGatewayService();
  CFEnvironment environment = CFEnvironment.SANDBOX;
  
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Plugin example app'),
        ),
        body: Center(
          child: Column(
            children: [
              TextButton(
                  onPressed: () => susbcriptionCheckout(),
                  child: const Text("Subscription Web Checkout Flow")),
            ],
          ),
        ),
      ),
    );
  }

  susbcriptionCheckout() async {
    try {
      cfPaymentGatewayService.setCallback(onSubscriptionVerify, onSubscriptionFailure);
      var subsriptionSession = CFSubscriptionSessionBuilder()
            .setEnvironment(environment)
            .setSubscriptionId(subscriptionId)
            .setSubscriptionSessionId(subscriptionSessionId)
            .build();
      
      var theme = CFThemeBuilder()
          .setNavigationBarBackgroundColorColor("#ffffff")
          .setNavigationBarTextColor("#ffffff")
          .build();
      var cfsubscriptionCheckout = CFSubscriptionPaymentBuilder()
          .setSession(subsriptionSession)
          .setTheme(theme)
          .build();
      cfPaymentGatewayService.doPayment(cfsubscriptionCheckout);
    } on CFException catch (e) {
      print(e.message);
    }
  }

  void onSubscriptionVerify(String subscriptionId) {
    print("Verify Subscription ===> $subscriptionId");
  }

  void onSubscriptionFailure(CFErrorResponse errorResponse, String data) {
    print(errorResponse.getMessage());
  }
}

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Step 4: Confirming the Payment

After the payment is completed, you need to confirm whether the payment was successful by checking the subscription status. Once the payment finishes, the user will be redirected back to your activity.
You must always verify payment status from your backend. Before delivering the goods or services, please ensure you call check the subscription status from your backend. Ensure you check the subscription status from your server endpoint.

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Testing

You should now have a working checkout button that redirects your customer to Cashfree Subscription Checkout. If your integration isn’t working:
  1. Open the Network tab in your browser’s developer tools.
  2. Click the button and check the console logs.
  3. Use console.log(session) inside your button click listener to confirm the correct error returned.