How to Use PayPal Invoicing API to Create and Send Invoices in PHP

Configure Your Environment

• Ensure you have the PayPal PHP SDK installed, which helps in interacting with the PayPal API endpoints. You can install it using Composer:

composer require paypal/rest-api-sdk-php

• Have your API credentials ready, including Client ID and Secret, which can be generated from the PayPal Developer Dashboard under the API credentials section.

Initialize API Context

• Create an `ApiContext` object which holds your credentials and the environment. This context will be used to make API calls to PayPal:

use PayPal\Rest\ApiContext;
use PayPal\Auth\OAuthTokenCredential;

$apiContext = new ApiContext(
    new OAuthTokenCredential(
        'YOUR_CLIENT_ID',     // ClientID
        'YOUR_CLIENT_SECRET'      // ClientSecret
    )
);

$apiContext->setConfig([
    'mode' => 'sandbox', // or 'live' for production mode
    'http.ConnectionTimeOut' => 30,
    'log.LogEnabled' => false,
    'log.FileName' => '',
    'log.LogLevel' => 'FINE', // Available options: DEBUG, INFO, WARN, ERROR
    'validation.level' => 'log',
    'cache.enabled' => true,
]);

Create an Invoice in PHP

• Instantiate an `Invoice` object and set the necessary data such as merchant info, billing info, items, and other details:

use PayPal\Api\Invoice;
use PayPal\Api\MerchantInfo;
use PayPal\Api\BillingInfo;
use PayPal\Api\InvoiceItem;
use PayPal\Api\ShippingInfo;

$invoice = new Invoice();

$invoice->setMerchantInfo(new MerchantInfo()
    ->setEmail('merchant@example.com')
    ->setFirstName('John')
    ->setLastName('Doe')
    ->setBusinessName('John Doe Online Store')
    ->setPhone('555-555-5555')
);

$billing = new BillingInfo();
$billing->setEmail('customer@example.com');
$invoice->setBillingInfo([$billing]);

$item = new InvoiceItem();
$item->setName('Sample Item')
    ->setQuantity(1)
    ->setUnitPrice(new \PayPal\Api\Currency(array('value' => 10, 'currency' => 'USD')));
$invoice->setItems([$item]);

Send the Invoice

• After configuring the invoice object, use the `create` method to create the invoice on PayPal's servers and then send it:

try {
    $invoice->create($apiContext);
    $invoice->send($apiContext);
    echo "Invoice sent successfully!";
} catch (Exception $ex) {
    echo "Error creating or sending invoice: " . $ex->getMessage();
}

Handle Errors and Exceptions

• Make sure to implement error handling to catch and manage API errors, including logging of exceptions for debugging and resilience:

try {
    $invoice->create($apiContext);
    $invoice->send($apiContext);
} catch (\PayPal\Exception\PayPalConnectionException $ex) {
    // This will print the detailed error message
    echo $ex->getData();
} catch (Exception $ex) {
    die($ex);
}

• Review the API logs and responses captured in case of exceptions to improve understanding and error resolution processes.