MercadoPago check if a payment/merchant order is fully paid

mercadopago-payment-is-paid.php

<?php
 /*
 * Keep in mind that this is heavily tied to the Laravel Framework
 *
 * $client_id
 * $client_secret
 * $externalReference
 */

MercadoPago\SDK::setClientId($client_id);
MercadoPago\SDK::setClientSecret($client_secret);

$paymentService = new MercadoPago\Payment();

$payments = collect($paymentService->search(['external_reference' => $externalReference]));

if ($payments->isEmpty()) {
    // No payments attempt made

    return;
}

$merchantOrder = MercadoPago\MerchantOrder::find_by_id($payments->first()->order->id);

$paidAmount = collect($merchantOrder->payments)
    ->filter(function ($payment) {
        return $payment->status === 'approved';
    })
    ->sum('transaction_amount');

// If the payment's transaction amount is equal (or bigger) than the merchant_order's amount you can release your items
if ($paidAmount >= $merchantOrder->total_amount) {
    // Fully paid!
} else {
    // Not paid yet
}