WordPress dashboard widget for PHP errors log

Jeff Starr recently posted on ways to monitor PHP errors. For some reason his method using WordPress’s wp-config.php file didn’t work for me, but I got the .htaccess version working OK.

I thought I’d knock out some code to display the latest errors as a widget on the WordPress dashboard.

As usual, this code is provided “as is”—use as you will, and let me know about any problems, but I can’t really offer support to people who aren’t comfortable with WordPress theme development. If anyone finds the time to wrap this up into a user-friendly plugin, do let me know (likewise if there’s already a plugin that does this better—I’ve not looked properly!).

Here goes, instructions are given after the code.

// PHP errors widget
function slt_PHPErrorsWidget() {
	$logfile = '/home/path/logs/php-errors.log'; // Enter the server path to your logs file here
	$displayErrorsLimit = 100; // The maximum number of errors to display in the widget
	$errorLengthLimit = 300; // The maximum number of characters to display for each error
	$fileCleared = false;
	$userCanClearLog = current_user_can( 'manage_options' );
	// Clear file?
	if ( $userCanClearLog && isset( $_GET["slt-php-errors"] ) && $_GET["slt-php-errors"]=="clear" ) {
		$handle = fopen( $logfile, "w" );
		fclose( $handle );
		$fileCleared = true;
	}
	// Read file
	if ( file_exists( $logfile ) ) {
		$errors = file( $logfile );
		$errors = array_reverse( $errors );
		if ( $fileCleared ) echo '<p><em>File cleared.</em></p>';
		if ( $errors ) {
			echo '<p>'.count( $errors ).' error';
			if ( $errors != 1 ) echo 's';
			echo '.';
			if ( $userCanClearLog ) echo ' [ <b><a href="'.get_bloginfo("url").'/wp-admin/?slt-php-errors=clear" onclick="return confirm('Are you sure?');">CLEAR LOG FILE</a></b> ]';
			echo '</p>';
			echo '<div id="slt-php-errors" style="height:250px;overflow:scroll;padding:2px;background-color:#faf9f7;border:1px solid #ccc;">';
			echo '<ol style="padding:0;margin:0;">';
			$i = 0;
			foreach ( $errors as $error ) {
				echo '<li style="padding:2px 4px 6px;border-bottom:1px solid #ececec;">';
				$errorOutput = preg_replace( '/[([^]]+)]/', '<b>[$1]</b>', $error, 1 );
				if ( strlen( $errorOutput ) > $errorLengthLimit ) {
					echo substr( $errorOutput, 0, $errorLengthLimit ).' [...]';
				} else {
					echo $errorOutput;
				}
				echo '</li>';
				$i++;
				if ( $i > $displayErrorsLimit ) {
					echo '<li style="padding:2px;border-bottom:2px solid #ccc;"><em>More than '.$displayErrorsLimit.' errors in log...</em></li>';
					break;
				}
			}
			echo '</ol></div>';
		} else {
			echo '<p>No errors currently logged.</p>';
		}
	} else {
		echo '<p><em>There was a problem reading the error log file.</em></p>';
	}
}

// Add widgets
function slt_dashboardWidgets() {
	wp_add_dashboard_widget( 'slt-php-errors', 'PHP errors', 'slt_PHPErrorsWidget' );	
} 
add_action( 'wp_dashboard_setup', 'slt_dashboardWidgets' );

Instructions

1. Make sure PHP error logging is set up as per Jeff’s post. I don’t think the above code is bothered which of his methods you use—as long as there’s a log file to read.
2. Paste the above code into your current theme’s functions.php file.
3. Set the value of the $logfile variable at the start to the absolute server path of your log file.

Notes

• The slt_ prefix is just what I use in my code to prevent clashes with other theme and plugin code.
• The “CLEAR LOG FILE” function is restricted so that only WP admins can do it.
• This code uses the Dashboard Widgets API introduced with WordPress 2.7, so it won’t work with WP versions below that (if anyone is cavalier enough to be running such outdated software…).