Accept PayPal with server-side-only integration

Build your own payment form to add PayPal payment to the checkout page

Overview

PayPal doesn’t require any input from the customer on the merchant website. The customer must be redirected to PayPay to provide the required information to process the transaction. After that, the customer is redirected back to the merchants website displaying the result of the payment.

Optionally, you can send the customer’s email with payment resource creation and it will be prefilled PayPal’s webpage.

You can see an example of PayPal on our demo page.

Before you begin

• Check the basic integration requirements.
• Familiarize yourself with the general Server-side-only integration guide.

Step 1: Create a payment type resource

server side

When creating the payment type PayPal, you need to send a request to the Unzer API. The response contains an id , this is later referred to as typeId. You will need this typeId to perform the transaction. The customer email is an optional field.

POST https://api.unzer.com/v1/types/paypal/

Body:
{
  "email": "tester1@gmail.com"
}

$unzer = new Unzer('s-priv-xxxxxxxxxx');

$paypal = new Paypal();
$paypal = $unzer->createPaymentType($paypal);

Paypal paypal = new Paypal();
Unzer unzer = new Unzer(new HttpClientBasedRestCommunication(), "s-priv-xxxxxxxxxx");
paypal = unzer.createPaymentType(paypal);

The response looks similar to the following example:

{
  "id": "s-ppl-skki29gw2fue",
  "method": "paypal",
  "recurring": false,
  "geoLocation": {
    "clientIp": "127.0.0.1",
    "countryCode": "DE"
  },
  "email": "t*****1@g*****m"
}

For more details on PayPal payment type creation, see API reference.

Step 2: Make a payment

server side

Option 1: Make a charge transaction

Now, make a charge transaction with the Paypal typeId that you created and the returnUrl leading back to your shop after the payment is finished on the external page. With the charge transaction, an amount is reserved but is not yet transferred. Initially the transaction is pending and a payment resource is created.

POST https://api.unzer.com/v1/payments/charges
   
{
  "amount" : "20",
  "currency": "EUR",
  "returnUrl": "https://www.my-shop-url.de/returnhandler",
  "resources" : {
    "typeId" : "s-ppl-jldsmlmiprwe"
  }
}

$unzer     = new UnzerSDK\Unzer('s-priv-xxxxxxxxxx');

$chargeInstance = new Charge(100.00, 'EUR', $returnUrl);
$typeId = 's-ppl-jldsmlmiprwe';
$transaction = $unzer->performCharge($chargeInstance, $typeId);

Unzer unzer = new Unzer("s-priv-xxxxxxxxxx");
Charge charge = unzer.charge(BigDecimal.ONE, Currency.getInstance("EUR"), "s-ppl-jldsmlmiprwe", new URL("https://www.my-shop-url.de/returnhandler"));

The response looks similar to the following example:

{
    "id": "s-chg-1",
    "isSuccess": false,
    "isPending": true,
    "isError": false,
    "redirectUrl": "https://payment.unzer.com/v1/redirect/ppl/s-sGYdGywWpxzW",
    "message": {
        "code": "COR.000.100.112",
        "merchant": "Request successfully processed in 'Merchant in Connector Test Mode'",
        "customer": "Your payments have been successfully processed in sandbox mode."
    },
    "amount": "20.0000",
    "currency": "EUR",
    "returnUrl": "https://www.my-shop-url.de/returnhandler",
    "date": "2021-05-10 00:51:03",
    "resources": {
        "paymentId": "s-pay-131937",
        "traceId": "70ddf3152a798c554d9751a6d77812ae",
        "typeId": "s-ppl-jldsmlmiprwe"
    },
    "paymentReference": "",
    "processing": {
        "uniqueId": "31HA07BC8157BD2BC04D483EFA914465",
        "shortId": "4845.3426.1987",
        "traceId": "70ddf3152a798c554d9751a6d77812ae"
    }
}

For a full description of the charge transaction, refer to the relevant server-side integration documentation page: Charge a payment (direct API calls), Charge a payment (PHP SDK), Charge a payment (Java SDK).

Forward the customer to the external payment page

After you charge the PayPal resource, implement the following flow:

1. Redirect the customer to the redirectUrl returned in the response to your charge request
2. The customer is forwarded to the PayPal payment page.
3. After a successful payment or abort on the PayPal page, the customer is redirected to the returnUrl specified in the initial charge call.

Option 2: Make an authorize transaction

You can also make an authorize transaction instead with the Paypal typeId that you created and the returnUrl leading back to your shop after the payment is finished on the external page. Initially the transaction will be pending and a payment resource is created. With the authorize transaction an amount is reserved but is not yet transferred. You will need to charge the payment at a later point.

POST https://api.unzer.com/v1/payments/authorize
   
{
  "amount" : "20",
  "currency": "EUR",
  "returnUrl": "https://www.my-shop-url.de/returnhandler",
  "resources" : {
    "typeId" : "s-ppl-jldsmlmiprwe"
  }
}

$unzer     = new UnzerSDK\Unzer('s-priv-xxxxxxxxxx');

$authorizationInstance = new Authorization(100.00, 'EUR', $returnUrl);
$transaction = $unzer->performAuthorization($authorizationInstance, $typeId);

Unzer unzer = new Unzer("s-priv-xxxxxxxxxx");
Authorization authorization = unzer.authorize(BigDecimal.ONE, Currency.getInstance("EUR"), "s-ppl-0ajzmaxcuvhc", new URL("https://www.my-shop-url.de/returnhandler"));

For a full description of the authorize transaction, see the relevant server-side-integration documentation page: Authorize a payment (direct API calls), Authorize a payment (PHP SDK), Authorize a payment (Java SDK).

Charge the authorization

Because the customer already accepted the payment with the authorize transaction, you can now charge the payment to transfer the money.

When you authorize before charge, the authorized amount is on hold for 29 days. Paypal however, recommends to charge the funds within the three-day honor period. The success of the charge is subject to risk and availability of funds on the authorized payment instrument.

POST https://api.unzer.com/v1/payments/s-pay-1/charges
   
{
  "amount": 20,
  "paymentReference": "Test charge transaction"
}

$unzer = new Unzer('s-priv-xxxxxxxxx');
$charge = $unzer->performChargeOnPayment('s-pay-1', new Charge());

Unzer unzer = new Unzer("s-priv-xxxxxxxxxx");
Charge charge = unzer.chargeAuthorization("s-pay-1");

The response looks similar to the following example:

{
    "id": "s-chg-1",
    "isSuccess": true,
    "isPending": false,
    "isError": false,
    "message": {
        "code": "COR.000.100.112",
        "merchant": "Request successfully processed in 'Merchant in Connector Test Mode'",
        "customer": "Your payments have been successfully processed in sandbox mode."
    },
    "amount": "20.0000",
    "currency": "EUR",
    "date": "2021-06-04 15:33:16",
    "resources": {
        "customerId": "s-cst-d6ae94482612",
        "paymentId": "s-pay-1",
        "basketId": "",
        "metadataId": "",
        "payPageId": "",
        "traceId": "4ebfbfcae640ff2823e2e65febd54037",
        "typeId": "s-ppl-4x3zn7i4bxyh"
    },
    "paymentReference": "Test charge transaction",
    "processing": {
        "uniqueId": "31HA07BC8198C2F9107E38AF14C45201",
        "shortId": "4867.4719.2103",
        "traceId": "4ebfbfcae640ff2823e2e65febd54037"
    }
}

Step 3: Check status of the payment

server side

Once the customer is redirected to the returnUrl, you can fetch the payment details from the API, by using the resources.paymentId from the charge response above to handle the payment according to its status. If the status of the payment is completed , the payment process has been finished successfully and can be considered as paid. Check all possible payment states here.

GET https://api.unzer.com/v1/payments/{payment_ID}

{
    "id": "s-pay-131937",
    "state": {
        "id": 1,
        "name": "completed"
    },
    "amount": {
        "total": "20.0000",
        "charged": "20.0000",
        "canceled": "0.0000",
        "remaining": "0.0000"
    },
    "currency": "EUR",
    "orderId": "",
    "invoiceId": "",
    "resources": {
        "customerId": "",
        "paymentId": "s-pay-131937",
        "basketId": "",
        "metadataId": "",
        "payPageId": "",
        "traceId": "70ddf3152a798c554d9751a6d77812ae",
        "typeId": "s-ppl-grpucjmy5zrk"
    },
    "transactions": [
        {
            "date": "2021-05-10 00:51:03",
            "type": "charge",
            "status": "success",
            "url": "https://api.unzer.com/v1/payments/s-pay-131937/charges/s-chg-1",
            "amount": "20.0000"
        }
    ]
}

Step 4: Display the payment result

client side

Use the information from the Check status of the payment step to display the payment result to your customer.
This can be the success or error page of your shop. If something went wrong, you can use the client message from the API response and show it to the customer.

Manage payment

server side

For more details on managing PayPal payments, such as refunding them, see Manage PayPal payments

Notifications

We recommend subscribing to the payment event to receive notifications about any changes to the payment resource. As soon as the event is triggered you should fetch the payment and update the order status in your shop according to its status.

  {
    "event":"payment.pending",
    "publicKey":"s-pub-xxxxxxxxxx",
    "retrieveUrl":"https://api.unzer.com/v1/payments/s-pay-774",
    "paymentId":"s-pay-774"
  }

For more details on implementing webhooks to receive notifications, see Notifications page.

Error handling

All requests to the API can result in an error that should be handled. Refer to the Error handling guide to learn more about Unzer API (and other) errors and handling them.

Test & go live

You should always test your integration before going live. First perform test transactions using test data. Next, check against Integration checklist and Go-live checklist to make sure the integration is complete and you’re ready to go live.

See also

• Manage API resources:
  • Manage API resources (direct API calls)
  • Manage API resources (PHP SDK)
  • Manage API resources (Java SDK)
• Unzer API basics