Paypal Single Payout - 'Json request malformed' - php

Question

I am trying to proceed single payout with Paypal Sandbox. The error I am getting is:
'MALFORMED_REQUEST_ERROR' - 'Json request malformed.'
After receiving the token successfully, I setup the single payment details array and encode json, and then use curl to post it, but no luck. The code goes like:
if ($token) {
$ch = curl_init();
$data = [
'sender_batch_header' => [
'email_subject' => "You have a payment",
'sender_batch_id' => '184328423'
],
'items' => [
'recipient_type' => "EMAIL",
'amount' => [
'value' => 12.00,
'currency' => "USD"
],
'receiver' => 'test123test#hotmail.com',
'note' => 'Hello World',
'sender_item_id' => "123"
],
];
$headers = [
'Content-Type:application/json',
'Authorization:Bearer ' . $token,
];
curl_setopt($ch, CURLOPT_URL, "https://api.sandbox.paypal.com/v1/payments/payouts?sync_mode=true");
// curl_setopt($ch, CURLOPT_HEADER, false);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
$result = curl_exec($ch);
if(empty($result))die("Error: No response.");
else
{
$json = json_decode($result);
print_r($json);
}
curl_close($ch);
}

Answer 1

It took some time for me to notice it. The answer:
$data = [
'sender_batch_header' => [
'email_subject' => "You have a payment",
'sender_batch_id' => $randId
],
'items' => [
[
'recipient_type' => "EMAIL",
'amount' => [
'value' => "12.00",
'currency' => "USD"
],
'receiver' => 'test123test#hotmail.com',
'note' => 'Hello World',
'sender_item_id' => "A123"
],
],
];