Quickstart

Instantiate a logger for the current class

Constructor injection can be used to automatically instantiate the logger:

EXT:my_extension/Classes/MyClass.php

<?php

declare(strict_types=1);

namespace MyVendor\MyExtension;

use Psr\Log\LoggerInterface;

class MyClass
{
    public function __construct(
        private readonly LoggerInterface $logger,
    ) {}
}

Log

Log a simple message (in this example with the log level "warning"):

EXT:my_extension/Classes/MyClass.php

$this->logger->warning('Something went awry, check your configuration!');

Provide additional context information with the log message (in this example with the log level "error"):

EXT:my_extension/Classes/MyClass.php

$this->logger->error('Passing {value} was unwise.', [
    'value' => $value,
    'other_data' => $foo,
]);

Values in the message string that should vary based on the error (such as specifying an invalid value) should use placeholders, denoted by { }. Provide the value for that placeholder in the context array.

$this->logger->warning() etc. are only shorthands - you can also call $this->logger->log() directly and pass the severity level:

EXT:my_extension/Classes/MyClass.php

// use Psr\Log\LogLevel;

$this->logger->log(LogLevel::CRITICAL, 'This is an utter failure!');

Set logging output

TYPO3 has the FileWriter enabled by default for warnings (LogLevel::WARNING) and higher severity, so all matching log entries are written to a file.

If the filename is not set, then the file will contain a hash like

var/log/typo3_<hash>.log, for example var/log/typo3_7ac500bce5.log.

typo3temp/var/log/typo3_<hash>.log, for example typo3temp/var/log/typo3_7ac500bce5.log.

A sample output looks like this:

Fri, 19 Jul 2023 09:45:00 +0100 [WARNING] request="5139a50bee3a1" component="TYPO3.Examples.Controller.DefaultController": Something went awry, check your configuration!
Fri, 19 Jul 2023 09:45:00 +0100 [ERROR] request="5139a50bee3a1" component="TYPO3.Examples.Controller.DefaultController": Passing someValue was unwise. - {"value":"someValue","other_data":{}}
Fri, 19 Jul 2023 09:45:00 +0100 [CRITICAL] request="5139a50bee3a1" component="TYPO3.Examples.Controller.DefaultController": This is an utter failure!