Magento 2: Replacement for Mage::log method?

Question

In Magento 1, if you wanted to send a message to the logs, you'd use a static method on the global Mage class.

Mage::log($message, Zend_Log::DEBUG, "my-log-file.log");

Is there an equivalent in Magento 2? I've googled through the dev docs site and haven't seen anything obvious that pops out. There's this Inchoo article, but it's from almost a year ago and so much has changed since then.

As a Magento 2 module developer, if I want to replace code like the following in Magento 1

Mage::log($message, Zend_Log::DEBUG, "my-log-file.log");

What's the bare minimum I need to do?

Answer 1

protected $logger;
public function __construct(\Psr\Log\LoggerInterface $logger)
{
    $this->logger = $logger;
}

You use debug, exception, system for PSR Logger for example:

$this->logger->info($message);
$this->logger->debug($message);

HINT:

Don't forget to run php bin/magento setup:di:compile

Answer 2

In magento2, You can also write to the logs using the Zend library like below :

$writer = new \Zend\Log\Writer\Stream(BP . '/var/log/test.log');
$logger = new \Zend\Log\Logger();
$logger->addWriter($writer);
$logger->info('Your text message');

Edited

You can also print PHP objects and arrays like below :

$logger->info(print_r($yourArray, true));

Answer 3

\Magento\Framework\App\ObjectManager::getInstance()
    ->get(\Psr\Log\LoggerInterface::class)->debug('message');

Answer 4

Temporary print log with new file

$writer = new \Zend\Log\Writer\Stream(BP . '/var/log/logfile.log');
$logger = new \Zend\Log\Logger();
$logger->addWriter($writer);
$logger->info('Simple Text Log'); // Simple Text Log
$logger->info('Array Log'.print_r($myArrayVar, true)); // Array Log

Factory Method

You need to inject \Psr\Log\LoggerInterface class into constructor to call logger object

protected $_logger;
public function __construct(
...
\Psr\Log\LoggerInterface $logger
...
) {
    $this->_logger = $logger;
}

public function logExample() {

    //To print string Output in debug.log
    $this->_logger->addDebug('Your Text Or Variables'); 
    
    // To print array Output in system.log
    $this->_logger->log('600', print_r($yourArray, true));

}

Or you directly use this code in phtml file:

To print string Output in debug.log

\Magento\Framework\App\ObjectManager::getInstance()
   ->get('Psr\Log\LoggerInterface')->debug('Your Message');

To print array Output in system.log

$myArray = array('test1'=>'123', 'test2'=>'123', 'test3'=>'123');
$level = '100'; // use one of: 100, 200, 250, 300, 400, 500, 550, 600
\Magento\Framework\App\ObjectManager::getInstance()
    ->get('Psr\Log\LoggerInterface')
    ->log($level, print_r($myArray, true));

Update: Latest Magento version:

Write logs using the Lamina library:

$writer = new \Laminas\Log\Writer\Stream(BP . '/var/log/logfile.log');
$logger = new \Laminas\Log\Logger();
$logger->addWriter($writer);
$logger->info('Simple Text Log'); // Simple Text Log
$logger->info('Array Log'.print_r($myArrayVar, true)); // Array Log

Answer 5

Magento 2.4+

$writer = new \Zend_Log_Writer_Stream(BP . '/var/log/testlog.log');
$logger = new \Zend_Log();
$logger->addWriter($writer);
$logger->info('testt'); // Print string type data
$logger->info('Data::' . print_r($arrData, true)); // Print array type data

Answer 6

In a simple way if you don't want to create dependency injection or anything else use below code it will store log in system.log file

$logger = \Magento\Framework\App\ObjectManager::getInstance()->get(\Psr\Log\LoggerInterface::class);
$logger->info('message');

That's all..

Answer 7

If you want to use default logger but custom file for logging (or other custom logic) you need to use custom logger handler:

class Logger extends Magento\Framework\Logger\Handler\Base
{
  /**
   * @var string
   */
  protected $fileName = '/var/log/my-log-file.log';

  /**
   * @var int
   */
  protected $loggerType = MonologLogger::DEBUG;
}

Then add it as handler somewhere within your code:

protected function addCustomLogHandler()
{
    $logger = Data::getCustomLogger();
    if(isset($this->_logger)){
        $this->_logger->pushHandler($logger);
    }
}

A step back in convenience IMO

Answer 8

You can use this packages

composer require cleatsquad/logger

Examples

\CleatSquad\Logger::log('test', 'test.log');
\CleatSquad\Logger::log('test', 'test.log', \Monolog\Logger::WARNING);
\CleatSquad\Logger::log(['test' => 'is an array'], 'test.log');

Or you can use Laminas

After magento 2.3.5 we replace Zend By Laminas

You can also write to the logs using the Lamina library like below :

$writer = new \Laminas\Log\Writer\Stream(BP . '/var/log/test.log');
$logger = new \Laminas\Log\Logger();
$logger->addWriter($writer);
$logger->info('Your text message');


$data = ["test" => "testing"];
$logger->debug(var_export($data, true));

Answer 9

UPDATED: 19/08/2019

If you are looking for elegant custom log handler, I recommend you to use Virtual Types (which doesn't need to add any PHP code)

Inspired from the answer of Petar Dzhambazov and halk, ladies and gentlemen I introduced you a better and shorter way instead of duplicated custom log code all the time.

StackOverflow\Example\etc\di.xml

<!-- Custom log file for StackOverflow ; Duplicate it as much as you want separate log file -->
<virtualType name="StackOverflow\Example\Model\Logger\VirtualDebug" type="Magento\Framework\Logger\Handler\Base">
    <arguments>
        <argument name="fileName" xsi:type="string">/var/log/stackoverflow/donald_trump.log</argument>
    </arguments>
</virtualType>
<virtualType name="StackOverflow\Example\Model\Logger\VirtualLogger" type="Magento\Framework\Logger\Monolog">
    <arguments>
        <argument name="name" xsi:type="string">DonaldTrump</argument>
        <argument name="handlers" xsi:type="array">
            <item name="debug" xsi:type="object"> StackOverflow\Example\Model\Logger\VirtualDebug</item>
        </argument>
    </arguments>
</virtualType>

USAGE

Vendor\Something\Model\DonaldTrump.php

<?php
/**
 * Copyright © 2016 Toan Nguyen <https://nntoan.github.io>. All rights reserved.
 * See COPYING.txt for license details.
 *
 * This is the file you want to inject your custom logger.
 * Of course, your logger must be an instance of \Psr\Log\LoggerInterface.
 */

namespace Vendor\Something\Model;

/**
 * DonaldTrump business logic file
 *
 * @package Vendor\Something\Model
 * @author  Toan Nguyen <https://github.com/nntoan>
 */
class DonaldTrump
{
    /**
     * @var \Psr\Log\LoggerInterface
     */
    private $logger;

    /**
     * DonaldTrump constructor.
     *
     * @param \Psr\Log\LoggerInterface $logger
     */
    public function __construct(
        \Psr\Log\LoggerInterface $logger,
    ) {
        $this->logger = $logger;
    }

    // 1 billion lines of code after this line
}

StackOverflow\Example\etc\frontend\di.xml

<type name="Vendor\Something\Model\DonaldTrump">
    <arguments>
        <argument name="logger" xsi:type="object">StackOverflow\Example\Model\Logger\VirtualLogger</argument>
    </arguments>
</type>

That's all, no extra PHP files or lines - use the advantages of Magento 2: Virtual Types!!!

Hope this helps ;)

Answer 10

No, there is no direct equivalent. It's a bit complicated now.

See: Logging to a custom file in Magento 2

Answer 11

for magento 2.3.4 you can use :

$writer = new \Zend_Log_Writer_Stream(BP . '/var/log/custom.log');
$logger = new \Zend_Log();
$logger->addWriter($writer);
$logger->info('text message');

Answer 12

Include psr logger class in your file using use and then call addDebug() method. This will print log message in var/log/debug.log file

use Psr\Log\LoggerInterface;

class demo {
  function demo()
  {
    //EDIT: Using debug instead of addDebug for PSR compatiblity
    $this->_objectManager->get('Psr\Log\LoggerInterface')->debug("your message goes here");
  }

}

Answer 13

$writer = new \Zend\Log\Writer\Stream(BP . '/var/log/test.log');
$logger = new \Zend\Log\Logger();
$logger->addWriter($writer);
$logger->info('Your text message');

Answer 14

You can use several formats.

Default logger

1: In Magento default format

public $_logger;
public function __construct(
    ...
    \Psr\Log\LoggerInterface $logger
    ...
) {
    $this->_logger = $logger;
}

public function logExample() {

    //To print string Output in debug.log
    $this->_logger->debug('Your Text Or Variables'); 
    
    // To print array Output in system.log
    $this->_logger->log('600', print_r($yourArray, true));

}

Custom logger

2: This will work with the older version of Magento 2.4.3:

$writer = new \Zend\Log\Writer\Stream(BP . '/var/log/test.log');
$logger = new \Zend\Log\Logger();
$logger->addWriter($writer);
$logger->info('Your text message');
$logger->info('getAllowProducts'.print_r($subject->getAllowProducts(), true));

3: This will work with the newest Magento 2.4.3+:

$writer = new \Zend_Log_Writer_Stream(BP . '/var/log/custom.log');
$logger = new \Zend_Log();
$logger->addWriter($writer);
$logger->info('Your text message');
$logger->info('getAllowProducts'.print_r($subject->getAllowProducts(), true));

Answer 15

1. Inject $logger class in constructor \Psr\Log\LoggerInterface $logger
   This is achieved by passing $logger as argument.

2. Initialize $logger in constructor

   $this->logger = $logger
   

3. In function within the class you want to log use the below line

   $this->logger->debug($message);
   $this->logger->log($level, $message);
   

Answer 16

If you need it within your single class with custom log file:

public function __construct(\Psr\Log\LoggerInterface $logger, \Magento\Framework\App\Filesystem\DirectoryList $dir) 
{
    $this->logger = $logger;
    $this->dir = $dir;

    $this->logger->pushHandler(new \Monolog\Handler\StreamHandler($this->dir->getRoot().'/var/log/custom.log'));
}

Answer 17

There is one update for logger in 2.2. You can enable logger for production mode by run SQL:

 "INSERT INTO core_config_data (scope, scope_id, path, value) VALUES ('default', '0', 'dev/debug/debug_logging', '1');"

Then you can use \Psr\Log\LoggerInterface for print log just like above answers:

protected $logger;

public function __construct(
  \Psr\Log\LoggerInterface $logger
) {
    $this->logger = $logger;
  }

public function yourFunction() {
    $data = ["test" => "testing"];
    $this->logger->debug(var_export($data, true));
}

Answer 18

magento 2 logs

you can try it...

$writer = new \Zend\Log\Writer\Stream(BP . '/var/log/test.log');
$logger = new \Zend\Log\Logger(); $logger->addWriter($writer);
$logger->info($category->getData());

Answer 19

For me in M2.3.4, this is the one-liner that works and allows me to log into any file:

(new \Zend_Log())->addWriter(new \Zend_Log_Writer_Stream(BP . '/var/log/custom.log'))->info(print_r($foo, true));

Though I am not sure if the Zend_Log_Writer_Stream is coming from my environment or from Magento, so just try it out.

Answer 20

Place PSR logger code in your constructor:

protected $logger;
public function __construct(\Psr\Log\LoggerInterface $logger)
{
    $this->logger = $logger;
}

then you can use in your function like:

$this->logger->info($message);

Answer 21

1 line approach:

\Magento\Framework\App\ObjectManager::getInstance() ->get(\Psr\Log\LoggerInterface::class)->info('yourmessage');