Flutter CC-Avenue Payment Gateway Integration ft. PHP

#flutter #php #tutorial #android

In today's digital era, businesses are constantly seeking secure and reliable payment gateways to facilitate seamless transactions. CCAvenue is a popular payment gateway in India, offering a wide range of payment options for online businesses. In this blog, we will explore how to integrate CCAvenue into a Flutter application using PHP server.

Note: There is no official SDK available for flutter, so we are going to integrate through Flutter Webview.

Prerequisites:

Before we begin, make sure you have the following requirements in place:

Flutter SDK installed on your machine
Basic knowledge of Flutter and PHP
CCAvenue merchant account credentials

Note: CCAvenue does not allow payment transaction in live or test mode until you whitelist your Domain/IP. For Whitelisting your domain, you can email them.

Lets understand how does transaction Handle through CCAvenue?

CCAvenue has two phase for completing transaction

Initiate Payment : In this step,client send amount and currency and other required details to server and than server encrypt these values to a single encrypted(lets says enc_val) string and send enc_val and access_code to client.

Note: When your CCAvenue approved and whitelisted for transaction then you can get following access_code,working_key and merchant_id from CCAvenue.

Generate enc_val: Merchant need to encrypt following set of parameters using encryption tool provided by CCAvenue(We will use PHP)

We will encrypt following String:

merchant_id=123&order_id=123456redirect_url=www.amazonaws.com/payment
/ccav_resp.phpcancel_url=www.amazonaws.com/payment/ccav_resp.phpamount=1.00&currency=INR

after encryption we will get string like

a5eed2d2a51358773bb1de741b0b2f1261308043c2a8f78bf59d9d3d5081f785792599d64876
220964ebdd1578ce633aae959b804f2b2d53cda3821baf5480b3a082ea89a0e6784af4fef98e0
54f3a5c78f0ec9e611a01dd7666e9903e6b5d62c7a11d8db869d665c0077a292cfa6aba80a1ab
a94882168ede009b2c3806a4b08c781e2e5a7d54411b5a288ff28d499bc9de

Parameter Name	Description	Type (length)
Merchant Id	Merchant Id is a unique identifier generated by CCAvenue for each activated merchant.	Numeric
Order Id	This ID is used by merchants to identify the order. Ensure that you send a unique id with each request. CCAvenue will not check the uniqueness of this order id. As it generates a unique payment reference number for each order which is sent by the merchant.	Alphanumeric (30)
Redirect Url	CCAvenue will post the status of the order along with the parameters to this URL.	Alphanumeric (100)
Cancel Url	CCAvenue will redirect the customer to this URL if the customer cancels the transaction on the billing page.	Alphanumeric (100)
Amount	Order amount	Numeric (12, 2)
Currency	Currency in which you want to process the transaction. AED - Arab Emirates dirham USD - United States Dollar SAR - Saudi Arabia Riyal INR – Indian Rupee SGD – Singapore Dollar GBP – Pound Sterling EUR – Euro, official currency of Eurozone	Alphabets (3)

Note: we will talk about cancel_url and redirect_url in the next steps.

Start payment in WebView: you can start payment in webview through following url

https://secure.ccavenue.com/transaction.do?command=initiateTransaction&encRequest=enc_val&access_code=access_code

Note for testing replace secure.ccavenue.com to test.ccavenue.com.

Response Handler: When a user completes a payment, either in case of failure or success, CCAvenue will send an encrypted string to either the redirect_url or cancel_url using a POST request.
- redirect_url: It refers to a webpage hosted on your server's domain/IP, which must be whitelisted by CCAVenue. This webpage will handle the necessary steps after the payment request is completed, including handling both failure and success scenarios.
- cancel_url: Similar to the redirect_url, the cancel_url is also hosted on your server's domain/IP. However, it specifically handles requests where the user cancels the payment.

Now we will use decryption tool to decrypt string given by CCAvenue
after payment complete.

Lets Start Integration (Server Side)

We need encryption and decryption function to encrypt and decrypted request.

create crypto.php and with following content:

Install required Library:

sudo apt-get install php7.4-openssl

Now we need to create a page that accept POST request and return enc_val and access_code.

ccAvenueRequestHandler.php

Note: you can edit page as per your requirement,but later on flutter side you need JavaScript function to get desired result.

We also need to create a page like above which accept POST request and return decrypted data.

ccavResponseHandler.php

Note: Following url should be accessible through whitelisted domain https://your-domain/ccavResponseHandler.php.

Integration in Flutter(Client):

Adding following to pubspec.yaml

dependencies:
  http: ^0.13.6
  webview_flutter: ^2.0.6 
  html:

Android Configuration: Change in build.gradle(android/app)

android {
    defaultConfig {
        minSdkVersion 19
    }
}

Create Payment handler Screen with following content: lets say payment_screen.dart:

isTesting (Variable):
- Description: A boolean variable used to indicate whether the application is in testing mode or production mode.
- Type: bool
jsChannels (Variable):
- Description: A set of JavascriptChannel objects that define the JavaScript channels available for communication between the Flutter app and the WebView.
- Type: Set<JavascriptChannel>
initPayment (Method):
- Description: This method is responsible for initializing the payment by making an HTTP POST request to the requestInitiateUrl with the specified amount.
- Parameters:
  - amount (Type: String): The amount for the payment.
- Returns: A Future object that resolves to the payment data in JSON format.
- Type: Future<dynamic>
onPageFinished (Method):
- Description: This method is called when the WebView finishes loading a page.
- Parameters:
  - url (Type: String): The URL of the loaded page.
- Returns: void
- Type: void
navigationDelegate (Method):
- Description: This method is used to control the navigation behavior of the WebView based on the requested URL.
- Parameters:
  - nav (Type: NavigationRequest): The navigation request object containing information about the requested URL.
- Returns: A NavigationDecision that determines whether to allow or prevent the navigation.
- Type: NavigationDecision