What about Handling Errors in Yii Framework?

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Yii includes a built-in error handler which makes error handling a much more pleasant experience than before. In particular, the Yii error handler does the following to improve error handling :

* All non-fatal PHP errors (e.g. warnings, notices) are converted into catchable exceptions.

* Exceptions and fatal PHP errors are displayed with detailed call stack information and source code lines in debug mode.

* Supports using a dedicated controller action to display errors.

* Supports different error response formats.

The error handler is enabled by default. You may disable it by defining the constant YII_ENABLE_ERROR_HANDLER to be false in the entry script of your application.

Using Error Handler : The error handler is registered as an application component named errorHandler. You may configure it in the application configuration like the following :

return [
    'components' => [
        'errorHandler' => [
            'maxSourceLines' => 20,
        ],
    ],
];

With the above configuration, the number of source code lines to be displayed in exception pages will be up to 20.

As aforementioned, the error handler turns all non-fatal PHP errors into catchable exceptions. This means you can use the following code to deal with PHP errors :

use Yii;
use yii\base\ErrorException;

try {
    10/0;
} catch (ErrorException $e) {
    Yii::warning("Division by zero.");
}
// execution continues...

If you want to show an error page telling the user that his request is invalid or unexpected, you may simply throw an HTTP exception, such as yii\web\NotFoundHttpException. The error handler will correctly set the HTTP status code of the response and use an appropriate error view to display the error message.

use yii\web\NotFoundHttpException;

throw new NotFoundHttpException();