Monolog is fully extensible, allowing you to adapt your logger to your needs.
See the page about log records to learn what makes up a log record before going further. This is essential to understand as all Handlers/Formatters/Processors need to deal with log records in one way or another.
Monolog provides many built-in handlers. But if the one you need does not
exist, you can write it and use it in your logger. The only requirement is
to implement Monolog\Handler\HandlerInterface
.
Let's write a PDOHandler to log records to a database. We will extend the abstract class provided by Monolog to keep things DRY.
<?php
use Monolog\Level;
use Monolog\Logger;
use Monolog\Handler\AbstractProcessingHandler;
class PDOHandler extends AbstractProcessingHandler
{
private bool $initialized = false;
private PDO $pdo;
private PDOStatement $statement;
public function __construct(PDO $pdo, int|string|Level $level = Level::Debug, bool $bubble = true)
{
$this->pdo = $pdo;
parent::__construct($level, $bubble);
}
protected function write(LogRecord $record): void
{
if (!$this->initialized) {
$this->initialize();
}
$this->statement->execute(array(
'channel' => $record->channel,
'level' => $record->level,
'message' => $record->formatted,
'time' => $record->datetime->format('U'),
));
}
private function initialize()
{
$this->pdo->exec(
'CREATE TABLE IF NOT EXISTS monolog '
.'(channel VARCHAR(255), level INTEGER, message LONGTEXT, time INTEGER UNSIGNED)'
);
$this->statement = $this->pdo->prepare(
'INSERT INTO monolog (channel, level, message, time) VALUES (:channel, :level, :message, :time)'
);
$this->initialized = true;
}
}
You can now use this handler in your logger:
<?php
$logger->pushHandler(new PDOHandler(new PDO('sqlite:logs.sqlite')));
// You can now use your logger
$logger->info('My logger is now ready');
The Monolog\Handler\AbstractProcessingHandler
class provides most of the
logic needed for the handler, including the use of processors and the formatting
of the record (which is why we use $record->formatted
instead of $record->message
).