Symfony: what and when to throw exceptions (validate)?

Question

symfony

Something I read out the docks on the forms, and then the question has matured like a banal one, but I can’t figure it out.
Actually how to write a handler in the classical way. I used to do this in pure PHP:

<?php
$error = [];

if (false) {
    $error['name_empty'] = 'Enter your name';
}

if (false) {
    $error['text_empty'] = 'Enter article text';
}

if (!$error) {
    // save/redirect
}

// допустим внизу форма или HTML просто
echo '<p>' . implode(', ', $error) . '</p>';

Can you post links to this thread.