Unable to Create invoice via rest api in magento 2.0 - php

Question

I have the below code to create invoice for order in magento 2.0
<?php
$adminUrl='http://xxxxx/index.php/rest/V1/integration/admin/token';
$ch = curl_init();
$data = array("username" => "xxxxx", "password" => "xxxxx");
$data_string = json_encode($data);
$ch = curl_init($adminUrl);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
'Content-Type: application/json',
'Content-Length: ' . strlen($data_string))
);
$token = curl_exec($ch);
$token= json_decode($token);
$headers = array("Authorization: Bearer $token");
$requestUrl1='http://xxxxx/index.php/rest/V1/invoices';
$ch1 = curl_init();
$ch1 = curl_init($requestUrl1);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$result1 = curl_exec($ch1);
$result1= json_decode($result1);
print_r($result1);
?>
It was giving me
{"message":"%fieldName is a required field.","parameters":{"fieldName":"entity"}}

Answer 1

try to pass Invoice data like this
$setHaders = array('Content-Type:application/json','Authorization:Bearer '.$adminToken);
$productData='{"entity":{"orderId":6,"items":[{"orderItemId":9,"qty":1},{"orderItemId":10,"qty":1}],"comments":[],"extensionAttributes":{}}}';
$requestURL= "{magento-url}/rest//V1/invoices";
$ch = curl_init();
curl_setopt($ch,CURLOPT_URL, $requestURL);
curl_setopt($ch,CURLOPT_POSTFIELDS, $productData);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_HTTPHEADER, $setHaders);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$result = curl_exec($ch);