Using PDO: fetch vs fetchObject for JSON printout - php

Question

I'm using PDO to grab records from a mysql table. The data will be encoded with json_encode() and printed through the Slim framework for the API:
$app->get('/get/profile/:id_user', function ($id_user) use ($app) {
$sql = 'SELECT * FROM user WHERE id_user = :id_user';
try {
$stmt = cnn()->prepare($sql);
$stmt->bindParam(':id_user', $id_user, PDO::PARAM_INT);
$stmt->execute();
$data = $stmt->fetch(PDO::FETCH_ASSOC); // THIS!!!
if($stmt->rowCount()) {
$app->etag(md5(serialize($data)));
echo json_encode($data,JSON_PRETTY_PRINT);
} else {
$app->notfound();
}
} catch(PDOException $e) {
echo $e->getMessage();
}
});
Should I use
$data = $stmt->fetch(PDO::FETCH_ASSOC);
or
$data = $stmt->fetchObject();
? Any direct benefits on fetching the data as an object? I've read some examples but they never explain why. The only usage for the resulting data will be to print it in JSON format. Thanks!

Answer 1

It doesn't matter. Though I'd cut an object out with Occam's razor.
Also your code is slightly wrong and redundant. Here is a proper version
$sql = 'SELECT * FROM user WHERE id_user = :id_user';
$stmt = cnn()->prepare($sql);
$stmt->bindParam(':id_user', $id_user, PDO::PARAM_INT);
$stmt->execute();
if ($data = $stmt->fetch()) {
$app->etag(md5(serialize($data)));
echo json_encode($data,JSON_PRETTY_PRINT);
} else {
$app->notfound();
}
there is no point in setting fetch mode for the every query when you can set it globally.
numrows() call is also useless.
and of course catching an exception is redundant, insecure and unreliable.