Paystack Plugin for Flutter

pub package

A Flutter plugin for making payments via Paystack Payment Gateway. Completely supports Android and iOS.

Installation

To use this plugin, add flutter_paystack as a dependency in your pubspec.yaml file.

Then initialize the plugin preferably in the initState of your widget.

import 'package:flutter_paystack/flutter_paystack.dart'

class PaymentPage extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => new _PaymentPageState();
}

class _PaymentPageState extends State<PaymentPage> {
  var paystackPublicKey = '[YOUR_PAYSTACK_PUBLIC_KEY]';

  @override
  void initState() {
    PaystackPlugin.initialize(publicKey: paystackPublicKey);
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    // Return your widgets
  }
}

No other configuration required - the plugin should work out of the box.

Making Payments

You can choose to initialize the payment locally or via Paystack's backend.

1. Initialize Via Paystack (Recommended)

1.a. This starts by making a HTTP POST request to https://api.paystack.co/transaction/initialize with the amount(in kobo), reference, etc in the request body and your paystack secret key in request header. The request looks like this:

// Required imports
import 'dart:async';
import 'dart:convert';
import 'package:http/http.dart' as http;

  initTransaction() async {
    var url = 'https://api.paystack.co/transaction/initialize';

    Map<String, String> headers = {
      'Authorization': 'Bearer $[YOUR_PAYSTACK_SECRET_KEY]',
      'Content-Type': 'application/json'
    };

    Map<String, String> body = {
      'reference': '[YOUR_GENERATED_REFERENCE]',
      'amount': 500000.toString(),
      'email': 'user@email.com'
    };

    http.Response response =
        await http.post(url, body: body, headers: headers);
    // Charge card
    _chargeCard(response.body);
  }

Please check the official documentation for the full details of payment initialization.

1.b If everything goes well, the initialization request returns a response with an access_code. You can then create a Charge object with the access code and card details. The charge is in turn passed to the PaystackPlugin.chargeCard() function for payment:

  PaymentCard _getCardFromUI() {
    // Using just the must-required parameters.
    return PaymentCard(
      number: cardNumber,
      cvc: cvv,
      expiryMonth: expiryMonth,
      expiryYear: expiryYear,
    );

    // Using Cascade notation (similar to Java's builder pattern)
//    return PaymentCard(
//        number: cardNumber,
//        cvc: cvv,
//        expiryMonth: expiryMonth,
//        expiryYear: expiryYear)
//      ..name = 'Segun Chukwuma Adamu'
//      ..country = 'Nigeria'
//      ..addressLine1 = 'Ikeja, Lagos'
//      ..addressPostalCode = '100001';

    // Using optional parameters
//    return PaymentCard(
//        number: cardNumber,
//        cvc: cvv,
//        expiryMonth: expiryMonth,
//        expiryYear: expiryYear,
//        name: 'Ismail Adebola Emeka',
//        addressCountry: 'Nigeria',
//        addressLine1: '90, Nnebisi Road, Asaba, Deleta State');
  }

  _chargeCard(http.Response response) {
    Map<String, dynamic> responseBody = json.decode(response.body);
    var charge = Charge()
      ..accessCode = responseBody['access_code']
      ..card = _getCardFromUI();

    PaystackPlugin.chargeCard(context,
        charge: charge,
        beforeValidate: (transaction) => handleBeforeValidate(transaction),
        onSuccess: (transaction) => handleOnSuccess(transaction),
        onError: (error, transaction) => handleOnError(error, transaction));
  }

  handleBeforeValidate(Transaction transaction) {
    // This is called only before requesting OTP
    // Save reference so you may send to server if error occurs with OTP
  }

  handleOnError(Object e, Transaction transaction) {
    // If an access code has expired, simply ask your server for a new one
    // and restart the charge instead of displaying error
  }


  handleOnSuccess(Transaction transaction) {
    // This is called only after transaction is successful
  }

2. Initialize Locally

Just send the payment details to PaystackPlugin.chargeCard

      // Set transaction params directly in app (note that these params
      // are only used if an access_code is not set. In debug mode,
      // setting them after setting an access code would throw an error
      Charge charge = Charge();
      charge.card = _getCardFromUI();
      charge
        ..amount = 2000
        ..email = 'user@email.com'
        ..reference = _getReference()
        ..putCustomField('Charged From', 'Flutter PLUGIN');
      _chargeCard();

Validating Card Details

You are expected to build the UI for your users to enter their payment details. For easier validation, wrap the TextFormFields inside a Form widget. Please check this article on validating forms on Flutter if this is new to you.

You can validate the fields with these methods:

card.validNumber

This method helps to perform a check if the card number is valid.

card.validCVC

Method that checks if the card security code is valid.

card.validExpiryDate

Method checks if the expiry date (combination of year and month) is valid.

card.isValid

Method to check if the card is valid. Always do this check, before charging the card.

card.getType

This method returns an estimate of the string representation of the card type(issuer).

chargeCard

Charging with the PaystackPlugin is quite straightforward. It requires the following arguments.

  1. context: your UI BuildContext. It's used by the plugin for showing dialogs for the user to take a required action, e.g inputting OTP.
  2. charge: You provide the payment details (PaymentCard, amount email etc) to an instance of the Charge object.
  3. beforeValidate: Pre-validation callback.
  4. onSuccess: callbacks for a successful payment.
  5. onError: callback for when an error occurs in the transaction. Provides you with a reference to the error object.

Verifying Transactions

This is quite easy. Just send a HTTP GET request to https://api.paystack.co/transaction/verify/$[TRANSACTION_REFERENCE]. Please, check the official documentaion on verifying transactions.

Testing your implementation

Paystack provides tons of payment cards for testing.

Running Example project

For help getting started with Flutter, view the online documentation.

An example project has been provided in this plugin. Clone this repo and navigate to the example folder. Open it with a supported IDE or execute flutter run from that folder in terminal.

Contributing, Issues and Bug Reports

The project is open to public contribution. Please feel very free to contribute. Experienced an issue or want to report a bug? Please, report it here. Remember to be descriptive.

Credits

Thanks to the authors of Paystack iOS and Android SDKS. I leveraged on their work to bring this plugin to fruition.

Libraries

flutter_paystack