site-proximo/admin/write_json.php

<?php
$rest_json = file_get_contents("php://input");
$_POST = json_decode($rest_json, true);


//var_dump($_POST);

$fp = fopen('../data/stock.json', 'w');
$result = fwrite($fp, json_encode($_POST));
fclose($fp);

if ($result) {
    echo 'Réussite !';
} else {
    echo 'Echec!
    '; // Allows to create a newline
    var_dump($_POST);
}