Contract Interface

1.1 Charge or Refund for user

• You want to charge or refund for user when User is doing order via ZaloPay or MomoPay. However, if you inject Concrete ZaloPay/MomoPay class into Controller so you can't change from ZaloPay <> MomoPay.

• At here, You're only injecting PaymentGateway interface and mapping that interface with MomoPay or ZaloPay via AppServiceProvider.php when you want to use Concrete class. They're ZaloPay or MomoPay.

• The way design is called Contract (Hợp Đồng) in Laravel above.

• You only need to implement PaymentGateway interface (contract) at Concrete class that are MomoPay/ZaloPay.....

<?php namespace App\Http\Controllers;

use Illuminate\Http\Request;

use App\Contracts\PaymentGateway;

class PaymentController extends Controller

{

protected $paymentGateway;

public function __construct(PaymentGateway $paymentGateway)

{

    $this->paymentGateway = $paymentGateway;

}

public function charge()

{

    if ($charged = $this->paymentGateway->charge(100000))

      var_dump($charged);

    return false;

}

public function refund()

{

     if ($refunded = $this->paymentGateway

                     ->refund('transaction123'))

        var_dump($refunded);

     return false;

}

}

1.2 Define PaymentGateway contract

<?php namespace App\Contracts;

interface PaymentGateway

{

public function charge($amount);

public function refund($transactionId);

}

2.1 MomoPaymentGateway

<?php namespace App\Services;

use App\Contracts\PaymentGateway;

class MomoPaymentGateway implements PaymentGateway

{

public function charge($amount)

{

  return (object) [

        'provider' => 'Momo',

        'service' => 'charge',

        'amount' => number_format($amount + 1000) . ' vnd',

        'fee' => '1.000 vnd',

        'message' => 'Success'

    ];

}

public function refund($transactionId)

{

  return (object) [

        'provider' => 'Momo',

        'service' => 'charge',

        'amount' => '99.000 vnd',

        'fee' => '1.000 vnd',

        'message' => 'Success'

      ];

}

}

2.2 ZaloPaymentGateway

<?php namespace App\Services;

use App\Contracts\PaymentGateway;

class ZaloPaymentGateway implements PaymentGateway

{

public function charge($amount)

{

  return (object) [

        'provider' => 'Zalo',

        'service' => 'charge',

        'amount' => number_format($amount) . ' vnd',

        'fee' => '0 vnd',

        'message' => 'Success'

      ];

}

public function refund($transactionId)

{

     return (object) [

        'provider' => 'Zalo',

        'service' => 'charge',

        'amount' => '100.000 vnd',

        'fee' => '0 vnd',

        'message' => 'Success'

      ];

}

}

3.1 Register ZaloPayPayment concrete with PaymentGateway contract

<?php namespace App\Providers;

use Illuminate\Support\ServiceProvider;

use App\Contracts\PaymentGateway;

use App\Services\ZaloPaymentGateway;

use App\Services\MomoPaymentGateway;

class AppServiceProvider extends ServiceProvider

{

/**

    * Register any application services.

    *

    * @return void

    */

public function register()

{

    $this->app->bind(PaymentGateway::class, function ($app) {

    // Return the desired payment gateway implementation here.

    // Example: return new MomoPaymentGateway();

     return new ZaloPaymentGateway();

    });

}

   public function boot() {}

}