Create your own Magento log files with Mage::log()

Magento comes with a built-in logging facility which can be enabled and configured in the back-end under System > Configuration > Developer. Alternatively you can enable the Developer Mode for the site to enable the log (on how to do this have a look at the index.php file). The exception log is always on.

Mage::log('My log entry');
Mage::log('My log message: '.$myVariable);
Mage::log($myArray);
Mage::log($myObject);
Mage::logException($e);

By default all log entries are appended to the var/log/system.log file and the exceptions are logged to var/log/exception.log. Objects and Arrays are automatically written via a print_r() directive. Watch out when using objects since these can get substantial in size. If you are in Developer Mode you can try if the object supports debug output via $object->debug().

Tip:
When using

Mage::log($myVariable);

If $myVariable is empty you won’t get an entry in the log. Add a comment before and at least you will know that the variable at that stage is empty:

Mage::log('My variable: '.$myVariable);

If you are distributing your own extensions it helps a lot if you don’t have to sift through heaps of unrelated log entries to identify an issue. The solution is to log to your own files.

Looking at the method definition in app/code/Mage.php you will find

public static function log($message, $level = null, $file = '') {}

so logging to your own file becomes as easy as

Mage::log('My log entry', null, 'mylogfile.log');

and et voilá all our log entries are in their own file at var/log/mylogfile.log. Exceptions can only be logged to one file

Reader Comments (8)

oliver
July 31, 2010 at 9:37 am / Permalink

Great article very useful!!!
Ela
February 8, 2011 at 1:31 pm / Permalink

Thanks a lot for your tips
Magento
June 16, 2011 at 1:21 pm / Permalink

I use Mage::log to dump object, but nothing saved. what’s wrong?
1. Robert Popovic
  June 17, 2011 at 9:31 am / Permalink
  
  Did you enable logging in: System > Configuration > Developer?
  If so, where are you looking? The log is in: [magento-root]/var/log/
  Also, how are you dumping the object?
Matthias
June 22, 2011 at 7:49 pm / Permalink
I seem to have a similar problem as “Magento”. Logging is enabled. And I use a static
```
Mage::log("Hello world.");
```
But nothing happens. Am I doing something wrong?
1. Robert Popovic
  June 23, 2011 at 4:54 pm / Permalink
  
  Are you sure your statement is executed? Where are you putting it? Does your web server process have write rights to var/log?
Pau
July 7, 2011 at 10:38 pm / Permalink

Hi!

I was having the same problem and I thought something was wrong. Just to be clear:

1. Enable developer mode in the .htaccess file by adding:
SetEnv MAGE_IS_DEVELOPER_MODE=true

2. Enable log settings going to:
System » Configuration » Developer, Log settings tab » Enabled » Yes.

Then… it worked!

Thanks Robert for this post. I’m just starting with Magento and it’s kind of weird for me not be able to use «echo» whereever I wont to find issues or to know where I am. I hope this log helps me!
Magento References | ew
May 4, 2012 at 2:33 pm / Permalink

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