Use PayPal Express

Overview

Use the getPayPalExpressCheckoutRedirectURL method to retrieve the RedirectURL by sending an Order object with PAYPAL_EXPRESS payment method.

Parameters

Response

Retrieve PayPal redirect URL

<?

require ('PATH_TO_AUTH');

$Order = new stdClass();
$Order->Language = 'en';
$Order->CustomerReference = 'APITEST'; // set customer reference (optional)
$Order->Currency = 'EUR';

$Order->Items = array();
$Order->Items[0] = new stdClass();
$Order->Items[0]->Code = 'my_subscription_1'; // send the product code
$Order->Items[0]->Quantity = 1;

$Order->PaymentDetails = new stdClass();
$Order->PaymentDetails->Type = 'PAYPAL_EXPRESS'; // payment method, must be PAYPAL_EXPRESS for the express flow to take place.
$Order->PaymentDetails->Currency = 'EUR';
$Order->PaymentDetails->CustomerIP = '91.220.121.21';

$PayPalExpress = new stdClass();
$PayPalExpress->Email='customer@email.com';
$PayPalExpress->ReturnURL = 'http://' . $_SERVER['HTTP_HOST'] . '/api/place_order_api_json_paypal_express_response.php';
$PayPalExpress->CancelURL = 'http://' . $_SERVER['HTTP_HOST'] . '/api/place_order_api_json_paypal_express_response.php' . '?cancel=true';
$Order->PaymentDetails->PaymentMethod = $PayPalExpress;    

// Call the method for retrieving Express Checkout redirect URL
$jsonRpcRequest = new stdClass();
$jsonRpcRequest->jsonrpc = '2.0';
$jsonRpcRequest->method = 'getPayPalExpressCheckoutRedirectURL';
$jsonRpcRequest->params = array($sessionID, $Order);
$jsonRpcRequest->id = $i++;
$redirectUrl = callRPC($jsonRpcRequest, $host);
header('Location:' . $redirectUrl);

Place order with PayPal Express 

<?php
declare(strict_types=1);

class Configuration
{


    public const MERCHANT_CODE = '';
    public const MERCHANT_KEY = '';
    public const URL = 'http://api.2checkout.com/rpc/6.0';
    public const ACTION = 'placeOrder';
    public const ADDITIONAL_OPTIONS = null;
    //array or JSON
    public const PAYLOAD = <<<JSON
{
  "Country": "us",
  "Currency": "USD",
  "CustomerIP": "91.220.121.21",
  "ExternalReference": "RPC_API_AVANGTE",
  "Language": "en",
  "Source": "testAPI.com",
  "BillingDetails": {
    "Address1": "Test Address",
    "City": "LA",
    "State": "California",
    "CountryCode": "US",
    "Email": "testcustomer@2Checkout.com",
    "FirstName": "Customer",
    "LastName": "2Checkout",
    "Zip": "12345"
  },
  "Items": [
    {
      "Code": "A90B3D8FDE",
      "Quantity": 1
    }
  ],
  "PaymentDetails": {
    "Currency": "USD",
    "CustomerIP": "91.220.121.21",
    "PaymentMethod": {
      "Email": "customer@example.com",
      "Token": "token-gotten-from-getPayPalExpressCheckoutRedirectURL",
      "ReturnURL": "http://secure.avangate.local/test/index.php",
      "CancelURL": "http://secure.avangate.local/test/create_order.php"
    },
    "Type": "PAYPAL_EXPRESS"
  }
}
JSON;
}

class Client
{
    private const LOGIN_METHOD = 'login';
    private $calls = 1;
    private $sessionId;


    private function generateAuth(): array
    {
        $merchantCode = Configuration::MERCHANT_CODE;
        $key = Configuration::MERCHANT_KEY;
        $date = gmdate('Y-m-d H:i:s');
        $string = strlen($merchantCode) . $merchantCode . strlen($date) . $date;
        $hash = hash_hmac('md5', $string, $key);

        return compact('merchantCode', 'date', 'hash');
    }


    public function login(string $url)
    {
        $payload = $this->generateAuth();
        $response = $this->call($url, array_values($payload), self::LOGIN_METHOD);
        $this->sessionId = $response['result'];
    }


    public function call(
        string $url = Configuration::URL,
        $payload = Configuration::PAYLOAD,
        string $action = Configuration::ACTION
    ): ?array {
        if (empty($this->sessionId) && $action !== self::LOGIN_METHOD) {
            $this->login($url);
        }
        if(is_string($payload)) {
            $payload = json_decode($payload, true);
        }
        if (!empty($this->sessionId)) {
            $payload = [$this->sessionId, $payload, Configuration::ADDITIONAL_OPTIONS];
        }
        $payload = array_filter($payload);

        $request = json_encode([
            'jsonrpc' => '2.0',
            'method' => $action,
            'params' => $payload,
            'id' => $this->calls++,
        ]);
        $curl = curl_init($url);
        curl_setopt($curl, CURLOPT_POST, 1);
        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, 0);
        curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, 0);
        curl_setopt($curl, CURLOPT_SSLVERSION, 0);
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($curl, CURLOPT_HTTPHEADER, array('Content-Type: application/json', 'Accept: application/json', 'Cookie: XDEBUG_SESSION=PHPSTORM'));
        curl_setopt($curl, CURLOPT_POSTFIELDS, $request);
        $response = curl_exec($curl);
        if(empty($response)) {
            die('Server unavailable');
        }
        echo $response . '</br>';
        return json_decode($response, true);;
    }
}
$client = new Client();
$result = $client->call();
var_dump($result);

Workflow

1. Authentication via login API method.
2. Retrieve PayPal redirect URL. When you retrieve the PayPal redirect URL, apart from the token you will also receive 2 parameters that are encoded: billingDetails and deliveryDetails. These have to be base64_decoded and the information should be used in the placeOrder API call (email, billing address etc.). 
3. Place the order with PayPal Express using the token sent by PayPal.