Magento2; update stock by REST API - rest

Question

I've set up a local Magento 2.1.2 environment with sample data. I'm trying to find the correct code for updating stocks through the REST api (catalogInventoryStockRegistryV1 - Put).
This is what i've got so far:
<?php
$adminUrl = 'http://www.localurl.pro/rest/V1/integration/admin/token/';
$ch = curl_init();
$data = array("username" => "admin", "password" => "66sRz97CZt7N[GdqFU");
$data_string = json_encode($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");
$requestUrl='http://www.localurl.pro/rest/V1/products/24-MB01/stockItems/1';
// Sample SKU
$sampleProductData = array(
"qty" => 100
);
$productData = json_encode(array('stockItem' => $sampleProductData));
// Prints: {"stockItem":{"qty":100}}
$ch = curl_init();
curl_setopt($ch,CURLOPT_URL, $requestUrl);
curl_setopt($ch,CURLOPT_POSTFIELDS, $productData);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT");
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
curl_close($ch);
var_dump($response);
This script gives the following error:
string(122) "{"message":"Server cannot understand Content-Type HTTP header media type application\/x-www-form-urlencoded","trace":null}"
I'm not sure what the message exactly means. Some help would be greatly appreciated.
Solution
Solution given by Mohan Gopal. 'Content-Type: application/json' was missing in the curl header.
<?php
$adminUrl = 'http://www.localhost.pro/rest/V1/integration/admin/token/';
$ch = curl_init();
$data = array("username" => "admin", "password" => "66sRz97CZt7N[GdqFU");
$data_string = json_encode($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);
//Use above token into header
$headers = array("Authorization: Bearer $token","Content-Type: application/json");
$skus = array(
'24-MB04' => 10,
'24-MB03' => 5
);
foreach ($skus as $sku => $stock) {
$requestUrl='http://www.localurl.pro/rest/V1/products/' . $sku . '/stockItems/1';
$sampleProductData = array(
"qty" => $stock
);
$productData = json_encode(array('stockItem' => $sampleProductData));
$ch = curl_init();
curl_setopt($ch,CURLOPT_URL, $requestUrl);
curl_setopt($ch,CURLOPT_POSTFIELDS, $productData);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT");
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
curl_close($ch);
var_dump($response);
unset($productData);
unset($sampleProductData);
}

Answer 1

Add the content type to header and change the header from
$headers = array("Authorization: Bearer $token");
to
$headers = array("Authorization: Bearer $token","Content-Type:
application/json");
after getting the token id on line 53.