Error Handling

CodeIgniter builds error reporting into your system through Exceptions, both the SPL collection, as well as a few custom exceptions that are provided by the framework. Depending on your environment’s setup, the the default action when an error or exception is thrown is to display a detailed error report unless the application is running under the production environment. In this case, a more generic message is displayed to keep the best user experience for your users.

• Using Exceptions
• Configuration
  • Logging Exceptions
• Custom Exceptions
  • PageNotFoundException
  • ConfigException
  • DatabaseException
  • RedirectException

Using Exceptions

This section is a quick overview for newer programmers, or for developers who are not experienced with using exceptions.

Exceptions are simply events that happen when the exception is “thrown”. This halts the current flow of the script, and execution is then sent to the error handler which displays the appropriate error page:

throw new \Exception("Some message goes here");

If you are calling a method that might throw an exception, you can catch that exception using a try/catch block:

try
{
    $user = $userModel->find($id);
}
catch (\Exception $e)
{
    die($e->getMessage());
}

If the $userModel throws an exception, it is caught and the code within the catch block is executed. In this example, the scripts dies, echoing the error message that the UserModel defined.

In the example above, we catch any type of Exception. If we only want to watch for specific types of exceptions, like a UnknownFileException, we can specify that in the catch parameter. Any other exceptions that are thrown and are not child classes of the caught exception will be passed on to the error handler:

catch (\CodeIgniter\UnknownFileException $e)
{
    // do something here...
}

This can be handy for handling the error yourself, or for performing cleanup before the script ends. If you want the error handler to function as normal, you can throw a new exception within the catch block:

catch (\CodeIgniter\UnknownFileException $e)
{
    // do something here...

    throw new \RuntimeException($e->getMessage(), $e->getCode(), $e);
}

Configuration

By default, CodeIgniter will display all errors in the development and testing environments, and will not display any errors in the production environment. You can change this by setting the CI_ENVIRONMENT variable in the .env file.

Logging Exceptions

By default, all Exceptions other than 404 - Page Not Found exceptions are logged. This can be turned on and off by setting the $log value of Config\Exceptions:

class Exceptions
{
    public $log = true;
}

To ignore logging on other status codes, you can set the status code to ignore in the same file:

class Exceptions
{
    public $ignoredCodes = [ 404 ];
}

Custom Exceptions

The following custom exceptions are available:

PageNotFoundException

This is used to signal a 404, Page Not Found error. When thrown, the system will show the view found at /app/views/errors/html/error_404.php. You should customize all of the error views for your site. If, in Config/Routes.php, you have specified a 404 Override, that will be called instead of the standard 404 page:

if (! $page = $pageModel->find($id))
{
    throw \CodeIgniter\Exceptions\PageNotFoundException::forPageNotFound();
}

You can pass a message into the exception that will be displayed in place of the default message on the 404 page.

ConfigException

This exception should be used when the values from the configuration class are invalid, or when the config class is not the right type, etc:

throw new \CodeIgniter\Exceptions\ConfigException();

This provides an HTTP status code of 500 and an exit code of 3.

DatabaseException

This exception is thrown for database errors, such as when the database connection cannot be created, or when it is temporarily lost:

throw new \CodeIgniter\Database\Exceptions\DatabaseException();

This provides an HTTP status code of 500 and an exit code of 8.

RedirectException

This exception is a special case allowing for overriding of all other response routing and forcing a redirect to a specific route or URL:

throw new \CodeIgniter\Router\Exceptions\RedirectException($route);

$route may be a named route, relative URI, or a complete URL. You can also supply a redirect code to use instead of the default (302, “temporary redirect”):

throw new \CodeIgniter\Router\Exceptions\RedirectException($route, 301);