Error Handling / Logging

Handling Errors in PHP

PHP provides multiple ways to handle errors effectively. The approach depends on whether you're in a development or production environment.

1️⃣ Error Handling Mechanisms in PHP

1. Using try...catch for Exception Handling
   Wrap critical code inside a try...catch block to gracefully handle exceptions.

   try {
       $result = 10 / 0; // Division by zero
   } catch (Exception $e) {
       echo "Caught Exception: " . $e->getMessage();
   }
   

2. Custom Error Handling with set_error_handler()
   Convert PHP errors into exceptions for better handling.

   function customErrorHandler($errno, $errstr, $errfile, $errline) {
       throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
   }
   set_error_handler("customErrorHandler");
   

3. Using register_shutdown_function() for Fatal Errors
   Detect fatal errors that would normally stop execution.

   function shutdownHandler() {
       $error = error_get_last();
       if ($error && $error['type'] === E_ERROR) {
           error_log("Fatal Error: " . $error['message']);
       }
   }
   register_shutdown_function('shutdownHandler');
   

Logging Practices in Production Environments

In production, logging errors instead of displaying them is critical for security and stability.

1️⃣ Disable Error Display in Production (php.ini)

Edit php.ini:

2️⃣ Use error_log() for Custom Logging

3️⃣ Use Monolog for Advanced Logging

Monolog provides structured logging with different log levels.

use Monolog\Logger;
use Monolog\Handler\StreamHandler;

$log = new Logger('app');
$log->pushHandler(new StreamHandler('/var/log/app.log', Logger::WARNING));

$log->warning('This is a warning log');
$log->error('This is an error log');

4️⃣ Logging in Drupal

Drupal provides the Watchdog logging system:

In production, use Syslog or Redis logging for better performance.

Best Practices for Error Handling and Logging

✔ Use try...catch blocks for expected errors.
✔ Log errors instead of displaying them in production.
✔ Disable error reporting in production (display_errors = Off).
✔ Use structured logging with Monolog or Drupal's logger().
✔ Monitor logs using tools like ELK Stack, Splunk, or Loggly.
✔ Implement alerting mechanisms (email, Slack, or monitoring tools) for critical errors.