Implement Custom Logging in WordPress Using error_log()

Need a reliable way to track bugs in WordPress? This tutorial walks you through setting up a custom write_log() function using PHP's error_log() to simplify debugging.

Define the write_log() Function

Here's how to use error_log() conditionally with WP_DEBUG:

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

Why This Matters

• Debug Mode: Ensures logging only happens during development.
• Structured Logs: Makes object/array logs readable.
• Efficient Debugging: Track both expected and unexpected output.

Logging in Action

function my_debug_function() {
    write_log('Debug started');
    $test_array = ['key' => 'value'];
    write_log($test_array);
}

Turn on Logging

define('WP_DEBUG', true);
define('WP_DEBUG_LOG', true);

Find the log in wp-content/debug.log or your server’s error log folder. Customize location via php.ini settings if needed.

Debugging Tips

• Disable logs on live sites: WP_DEBUG = false
• Keep log files secure and hidden from public access.
• Limit usage to development environments only.

Further Documentation

• WordPress error_log()
• WP_DEBUG in WordPress
• PHP Docs: error_log()

By using a tailored logging function, developers gain full control over debugging messages and performance monitoring in WordPress.