PHP: Save file to a specific directory - php

Question

I have this diretorio.php file that grabs the user id in Joomla and creates a directory with that id (if it doesn't exist yet):
/* Get the current user id */
$user = JFactory::getUser();
$usr_id = $user->get('id');
/*Define the path to this user's directory */
$diretorio=$_SERVER['DOCUMENT_ROOT']."/Apps/files/".$usr_id;
/*Create the user's directory if it doesn't exist */
if (!file_exists($diretorio) and !is_dir($diretorio)) {
mkdir($diretorio, 0755);
};
Now, I want to save a file with data in an object, using an Ajax that triggers another PHP file to the same directory created above:
$myFile = $diretorio."/dados.json";
$fh = fopen($myFile, 'w') or die("não é possível abrir o ficheiro");
$stringData = $_POST['data'];
$stringData='{ "data":'.json_encode($stringData).'}';
fwrite($fh, $stringData);
fclose($fh);
However, the file isn't created. If I replace the first line to:
$myFile = "dados.json";
It will create the file in the same directory where this PHP script is stored.

Answer 1

I would recommend using Joomla coding standards like so:
$user = JFactory::getUser();
$usr_id = $user->get('id');
$diretorio = JPATH_SITE . "/Apps/files/" . $usr_id;
if (!JFolder::exists($diretorio)) {
JFolder::create($diretorio, 0775);
}
$myFile = $diretorio."/dados.json";
$stringData = $_POST['data'];
$stringData = '{ "data":'.json_encode($stringData).'}';
JFile::write($myFile, $stringData);
JPATH_SITE is the root of your Joomla site