Setting json formatter in monolog

Question

How can the logs be set to json format in monolog....

$logger = new StreamHandler(__DIR__.'/my_app.log');
$logger->setFormatter( new JsonFormatter() );
$logger->pushHandler($logger);

This doesn't seems to be correct as it shows error

Call to undefined method Monolog\Logger::setFormatter()

also I would like my log to be recorded like this:

message{
a="something";
b="something else"
}

instead of:

message{a="something";b="something else"}

Answer 1

In case some other person has this question also: The formatter can be set to the handler, not the logger.

use Monolog\Formatter\JsonFormatter;
use Monolog\Handler\StreamHandler;
use Monolog\Logger;

$logger = new Logger('your_channel_name');
$handler = new StreamHandler('your/dir.log');
$handler->setFormatter( new JsonFormatter() );
$logger->pushHandler($handler);

// and then where ever in the code
$logger->info('your message', ["var1" => "value 1", "otherVar" => "otherValue"]);

// it will result in a parsable output similar to this:
// {
//   "message":"your message",
//   "context": {
//      "var1":"value 1", 
//      "otherVar":"otherValue"
//   }, 
//   "level":200, 
//   "level_name":"INFO",  
//   "channel":"your_channel_name",
//   "datetime":"2021-06-25T10:54:10.116817+00:00",
//   "extra":{}
// }

The documentation itself is not the best, but a start as well.