WordPress debugging

Question

How can I write debug messages from my WordPress plugin?

Debugging in WordPress describes how can I enable the wp-content/debug.log file. But how can I write to it? Is there any logging method like wp_log($msg) or something? I didn't find such.

Answer 1

If WP_DEBUG_LOG is set to true, the error_log-INI setting is set:

ini_set( 'error_log', WP_CONTENT_DIR . '/debug.log' ); 

To write to that file, you can use the error_log-function:

error_log("This message is written to the log file"); 

This function is not specific to WordPress and can be used in any PHP script.

Answer 2

Here's a simple function you can use; it will only log a message if WP_DEBUG is enabled:

function log_me($message) {     if ( WP_DEBUG === true ) {         if ( is_array($message) || is_object($message) ) {             error_log( print_r($message, true) );         } else {             error_log( $message );         }     } } 

You can call the log_me() function like this in your theme template(s):

log_me( 'This is a message for debugging purposes' ); 

Which will appear in your /wp-content/debug.log as the following line:

[13-Apr-2013 20:59:17 UTC] This is a message for debugging purposes