Question

Starting with a default install of Symfony2, I logged an INFO-level message using this line in my controller:

$this->get('logger')->info('foo');

and this showed up in app/logs/dev.log:

[2012-07-06 10:56:19] app.INFO: foo [] []

What are those empty square braces?

Answer 1

From Monolog\Formatter\LineFormatter, it looks like the first [] is %context%, and the second is %extra%. Neither are populated by default. See this useful doc for how to
replace the empty square brackets with a session token.

If you want to fill in %context%, here’s an idea (don’t use this for real, though):

$trace = debug_backtrace(); 
$record['context'] = $trace[3]['file'].':'.$trace[3]['line']; 

See:

• https://groups.google.com/d/topic/symfony-devs/aycdKqEPUlk/discussion
• https://groups.google.com/d/topic/symfony-devs/7fxFTS0EK4g/discussion