Debugging toolbar

The debugging toolbar is a utility for developers that displays debug information about a MediaWiki page at the bottom of the browser window. You can enable it with the $wgDebugToolbar variable in LocalSettings.php:

$wgDebugToolbar = true;

The toolbar

The toolbar consists of multiple sections that you click to expand or collapse:

The sections are:

Console

An area where MediaWiki code can write messages. Superior to echoing text to the browser.

Queries

A list of SQL queries executed on that page, with timing (requires $wgDebugDumpSql ).

Debug log

A list of the debug messages printed during the page execution.

Request

HTTP request information.

PHP includes

A list of included PHP files during the page execution.

The rest

Statistics about the software versions, execution time, and memory used.

Click any section to expand it and see the data. Click it again to close. Use your browser's Find feature to search the data.

The MediaWiki and PHP links lead to their respective websites (https://www.mediawiki.org and https://php.net).

Logging messages to the console

See the file includes/debug/MWDebug.php for available functions. Here are a few useful examples:

use MWDebug

Load the module at the top of your file before calling any functions.

MWDebug::init()

Must be called first to enable most other functions

MWDebug::log('your message here')

Send an arbitrary message to the Console

MWDebug::warning('Never do that again')

Send a warning message to the Console

MWDebug::deprecated('Function Foobar() is dead')

Send a message to the Console about deprecated functionality, including a backtrace

MWDebug::queryTime(MWDebug::query('select foo from bar'));

Execute the given SQL and report its time in the Queries section.