### Install Monolog via Composer

Source: https://github.com/seldaek/monolog/blob/main/README.md

Use this command to add the Monolog package to your project dependencies.

```bash
composer require monolog/monolog
```

--------------------------------

### Initialize and Use Monolog

Source: https://github.com/seldaek/monolog/blob/main/README.md

Create a logger instance, attach a stream handler, and log messages at different severity levels.

```php
<?php

use Monolog\Level;
use Monolog\Logger;
use Monolog\Handler\StreamHandler;

// create a log channel
$log = new Logger('name');
$log->pushHandler(new StreamHandler('path/to/your.log', Level::Warning));

// add records to the log
$log->warning('Foo');
$log->error('Bar');
```

--------------------------------

### Configure a Logger with Handlers

Source: https://github.com/seldaek/monolog/blob/main/doc/01-usage.md

Initializes a logger instance and attaches StreamHandler and FirePHPHandler to the stack.

```php
<?php

use Monolog\Level;
use Monolog\Logger;
use Monolog\Handler\StreamHandler;
use Monolog\Handler\FirePHPHandler;

// Create the logger
$logger = new Logger('my_logger');
// Now add some handlers
$logger->pushHandler(new StreamHandler(__DIR__.'/my_app.log', Level::Debug));
$logger->pushHandler(new FirePHPHandler());

// You can now use your logger
$logger->info('My logger is now ready');
```

--------------------------------

### Initialize and use SocketHandler in PHP

Source: https://github.com/seldaek/monolog/blob/main/doc/sockets.md

Configures a logger with a persistent Unix socket handler. Ensure the socket path is accessible by the process user.

```php
<?php

use Monolog\Logger;
use Monolog\Handler\SocketHandler;

// Create the logger
$logger = new Logger('my_logger');

// Create the handler
$handler = new SocketHandler('unix:///var/log/httpd_app_log.socket');
$handler->setPersistent(true);

// Now add the handler
$logger->pushHandler($handler, Level::Debug);

// You can now use your logger
$logger->info('My logger is now ready');
```

--------------------------------

### Configuring a LineFormatter

Source: https://github.com/seldaek/monolog/blob/main/doc/01-usage.md

Create a custom log format by instantiating a LineFormatter with a template string and date format, then attaching it to a handler.

```php
<?php

// the default date format is "Y-m-d\TH:i:sP"
$dateFormat = "Y n j, g:i a";

// the default output format is "[%datetime%] %channel%.%level_name%: %message% %context% %extra%\n"
// we now change the default output format according to our needs.
$output = "%datetime% > %level_name% > %message% %context% %extra%\n";

// finally, create a formatter
$formatter = new LineFormatter($output, $dateFormat);

// Create a handler
$stream = new StreamHandler(__DIR__.'/my_app.log', Level::Debug);
$stream->setFormatter($formatter);

// bind it to a logger object
$securityLogger = new Logger('security');
$securityLogger->pushHandler($stream);
```

--------------------------------

### Configure log channels

Source: https://github.com/seldaek/monolog/blob/main/doc/01-usage.md

Create separate logger instances with unique names to identify the source of log records.

```php
<?php

use Monolog\Level;
use Monolog\Logger;
use Monolog\Handler\StreamHandler;
use Monolog\Handler\FirePHPHandler;

// Create some handlers
$stream = new StreamHandler(__DIR__.'/my_app.log', Level::Debug);
$firephp = new FirePHPHandler();

// Create the main logger of the app
$logger = new Logger('my_logger');
$logger->pushHandler($stream);
$logger->pushHandler($firephp);

// Create a logger for the security-related stuff with a different channel
$securityLogger = new Logger('security');
$securityLogger->pushHandler($stream);
$securityLogger->pushHandler($firephp);

// Or clone the first one to only change the channel
$securityLogger = $logger->withName('security');
```

--------------------------------

### Create a custom PDOHandler

Source: https://github.com/seldaek/monolog/blob/main/doc/04-extending.md

Implement a custom handler by extending AbstractProcessingHandler to log records into a database. The write method handles the persistence logic using the formatted record data.

```php
<?php

use Monolog\Level;
use Monolog\Logger;
use Monolog\LogRecord;
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;
    }
}
```

--------------------------------

### Register the custom handler

Source: https://github.com/seldaek/monolog/blob/main/doc/04-extending.md

Add the custom handler to a logger instance using pushHandler.

```php
<?php

$logger->pushHandler(new PDOHandler(new PDO('sqlite:logs.sqlite')));

// You can now use your logger
$logger->info('My logger is now ready');
```

--------------------------------

### Add context to log records

Source: https://github.com/seldaek/monolog/blob/main/doc/01-usage.md

Pass an array of data as the second argument to logging methods to include contextual information.

```php
<?php

$logger->info('Adding a new user', ['username' => 'Seldaek']);
```

--------------------------------

### Resetting the Logger State

Source: https://github.com/seldaek/monolog/blob/main/doc/01-usage.md

Use this method to flush buffers and reset internal state, effectively clearing memory between background tasks.

```php
$logger->reset();
```

--------------------------------

### Using Level enum

Source: https://github.com/seldaek/monolog/blob/main/UPGRADE.md

Replace Logger constants with the Level enum cases or their integer values.

```php
Level::Warning
Level::Warning->value
```

--------------------------------

### Converting LogRecord to array

Source: https://github.com/seldaek/monolog/blob/main/UPGRADE.md

Use toArray() to retrieve a Monolog 1/2 style array from a LogRecord object.

```php
$record->toArray()
```

--------------------------------

### Accessing formatted log records

Source: https://github.com/seldaek/monolog/blob/main/doc/01-usage.md

Handlers typically store the final string representation of a log entry in the formatted property of the record.

```php
$record->formatted
```

--------------------------------

### Add extra data with processors

Source: https://github.com/seldaek/monolog/blob/main/doc/01-usage.md

Use a callable processor to modify the record's extra data globally or per handler.

```php
<?php

$logger->pushProcessor(function ($record) {
    $record->extra['dummy'] = 'Hello world!';

    return $record;
});
```

--------------------------------

### Accessing LogRecord properties

Source: https://github.com/seldaek/monolog/blob/main/UPGRADE.md

Use object property access instead of array access for log records in Monolog 3.0.0.

```php
$record->context
```

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