eSewa Wallet #

A Flutter package for integrating eSewa payments using flutter_inappwebview.

Features #

• Seamless integration of eSewa payments for live and dev environments.
• Automatic HMAC-SHA256 signature generation for secure transactions.
• Decodes and processes Base64-encoded success responses.
• Structured success (EsewaResponse) and failure (EsewaFailure) callbacks.
• Adheres to SOLID principles for maintainability and extensibility.

Installation #

Add the following to your pubspec.yaml:

dependencies:
  esewa_wallet: ^1.0.0

Run:

flutter pub get

UsagePre #

1. Import the package:

import 'package:esewa_wallet/esewa_wallet.dart';

2. Create a PaymentData instance with your payment details and secret key:

final paymentData = PaymentData(
  amount: '100',
  taxAmount: '10',
  totalAmount: '100',
  transactionUuid: '11-201-13',
  productCode: 'EPAYTEST',
  productServiceCharge: '0',
  productDeliveryCharge: '0',
  successUrl: 'https://developer.esewa.com.np/success',
  failureUrl: 'https://developer.esewa.com.np/failure',
  secretKey: '8gBm/:&EnhH.1/q', // UAT secret key
);

3. Initiate payment using the ESewaPayment singleton for either live or dev environment:

// For development (UAT) environment
final paymentService = ESewaPayment.dev(paymentData: paymentData);
paymentService.initiatePayment(
  context,
  onSuccess: (response) {
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: Text('Payment Successful: ${response.transactionCode} (${response.status})'),
      ),
    );
  },
  onFailure: (failure) {
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text('Payment Failed: ${failure.error}')),
    );
  },
);

// For live environment
final paymentDataLive = PaymentData(
  amount: '100',
  taxAmount: '10',
  totalAmount: '100',
  transactionUuid: '11-201-13',
  productCode: 'Merchant code provided by eSewa',
  productServiceCharge: '0',
  productDeliveryCharge: '0',
  successUrl: 'https://your-live-success-url.com',
  failureUrl: 'https://your-live-failure-url.com',
  secretKey: 'your-live-secret-key', // Replace with live secret key
);
final paymentServiceLive = ESewaPayment.live(paymentData: paymentDataLive);
paymentServiceLive.initiatePayment(
  context,
  onSuccess: (response) {
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: Text('Payment Successful: ${response.transactionCode} (${response.status})'),
      ),
    );
  },
  onFailure: (failure) {
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text('Payment Failed: ${failure.error}')),
    );
  },
);

Payment Flow #

1. The ESewaWallet submits payment data to the eSewa API via a WebView.
2. Users are redirected to the eSewa login page to enter their eSewa ID and MPIN.
3. A 6-digit verification token is sent to the user's mobile (SMS) or email. For testing in the dev environment, use the token 123456.
4. On successful payment, the user is redirected to the successUrl with a Base64-encoded response (in the data query parameter), which is decoded into an EsewaResponse.
5. On failure, the user is redirected to the failureUrl, and an EsewaFailure is returned with an error message.

Dev Credentials #

Use the following credentials for testing in the dev environment:

• eSewa ID: 9806800001, 9806800002, 9806800003, 9806800004, or 9806800005
• MPIN: 1122
• Token: 123456

These credentials allow you to test the payment flow without needing to receive a real token via SMS or email.

Signature Generation #

The package automatically generates a Base64-encoded HMAC-SHA256 signature using the fields total_amount,transaction_uuid,product_code in that order. Example:

• Input: total_amount=100,transaction_uuid=11-201-13,product_code=EPAYTEST
• Secret Key: 8gBm/:&EnhH.1/q
• Output: 4Ov7pCI1zIOdwtV2BRMUNjz1upIlT/COTxfLhWvVurE=

Success Response #

On successful payment, the response is Base64-encoded in the successUrl (e.g., https://developer.esewa.com.np/success?data=<base64>). The decoded response is converted to an EsewaResponse with fields like:

• transaction_code (e.g., "000AWEO")
• status (e.g., "COMPLETE")
• total_amount (e.g., "1000.0")
• transaction_uuid (e.g., "250610-162413")
• product_code (e.g., "EPAYTEST")
• signed_field_names (e.g., "transaction_code,status,total_amount,transaction_uuid,product_code,signed_field_names")
• signature (e.g., "62GcfZTmVkzhtUeh+QJ1AqiJrjoWWGof3U+eTPTZ7fA=")

The package does not verify the response signature in this version. To enable verification, ensure the secretKey is provided to SignatureGenerator.verifyResponseSignature (not implemented here).

Example #

See the example/ directory for a complete sample app demonstrating both live and dev environments.

License #

This plugin is released under the MIT License. See LICENSE for details.