Introduction

When you first start using OctoberCMS, error and exception handling is already configured for you. There are two ways the event log can be accessed:

  1. The event log can be viewed in the file system by opening the file storage/logs/system.log.
  2. Alternatively it can be viewed via the Administration area by navigating to System > Logs > Event Log.

Log entries are always created when an error page is shown and for certain exception types.

Configuration

Error detail

The amount of error detail your application displays through the browser is controlled by the debug configuration option in your config/app.php configuration file. By default detailed error reporting is turned on so it is helpful to see detailed error information which can be useful for debugging and troubleshooting issues. When this feature is turned off, when there is a problem in a page, a generic error message will be displayed.

For local development, you should set the debug value to true. In your production environment, this value should always be false.

/*
|--------------------------------------------------------------------------
| Application Debug Mode
|--------------------------------------------------------------------------
|
| When your application is in debug mode, detailed error messages with
| stack traces will be shown on every error that occurs within your
| application. If disabled, a simple generic error page is shown.
|
*/

'debug' => false,

Log file modes

October supports single, daily, syslog and errorlog logging modes. For example, if you wish to use daily log files instead of a single file, you should simply set the log value in your config/app.php configuration file:

'log' => 'daily'

Available exceptions

October comes with several basic exception types out of the box.

Application exception

The October\Rain\Exception\ApplicationException class, aliased as ApplicationException, is the most common exception type that is used when a simple application condition has failed.

throw new ApplicationException('You must be logged in to do that!');

The error message will be simplified and will never include any sensitive information like the php file and line number.

System exception

The October\Rain\Exception\SystemException class, aliased as SystemException, is used for errors that are critical to the system functioning and are always logged.

throw new SystemException('Unable to contact the mail server API');

When this exception is thrown a detailed error message is shown with the file and line number where it occured.

Validation exception

The October\Rain\Exception\ValidationException class, aliased as ValidationException, is used for errors that relate directly to a form submission and an invalid field. The message should contain an array with fields and error messages.

throw new ValidationException(['username' => 'Sorry that username is already taken!']);

You can also pass an instance of the validation service.

$validation = Validator::make(...);

if ($validation->fails()) {
    throw new ValidationException($validation);
}

When this exception is thrown the AJAX framework will provide this information in a usable format and focus the first invalid field.

AJAX exception

The October\Rain\Exception\AjaxException class, aliased as AjaxException, is considered a "smart error" and will return the HTTP code 406. This allows them to pass response contents as if they were a successful response.

throw new AjaxException(['#flashMessages' => $this->renderPartial(...)]);

When this exception is thrown the AJAX framework will follow the standard error workflow but will also refresh specified partials.

Exception handling

All exceptions are handled by the October\Rain\Foundation\Exception\Handler class. This class contains two methods: report and render that dictate if an error should be logged and how to respond to an error.

However, you may specify custom handlers if needed using the App::error method. Handlers are called based on the type-hint of the Exception they handle. For example, you may create a handler that only handles RuntimeException instances:

App::error(function(RuntimeException $exception) {
    // Handle the exception...
});

If an exception handler returns a response, that response will be sent to the browser and no other error handlers will be called:

App::error(function(InvalidUserException $exception) {
    return 'Sorry! Something is wrong with this account!';
});

To listen for PHP fatal errors, you may use the App::fatal method:

App::fatal(function($exception) {
    //
});

If you have several exception handlers, they should be defined from most generic to most specific. So, for example, a handler that handles all exceptions of type Exception should be defined before a custom exception type such as SystemException.

Where to place error handlers

Error handler registrations, like event handlers, generally fall under the category of "bootstrap code". In other words, they prepare your application to actually handle requests, and usually need to be executed before a route or controller is actually called. The most common place is the boot method of a Plugin registration file. Alternatively, plugins can supply a file named init.php in the plugin directory that you can use to place error handler registrations.

HTTP exceptions

Some exceptions describe HTTP error codes from the server. For example, this may be a "page not found" error (404), an "unauthorized error" (401) or even a developer generated 500 error. In order to generate such a response from anywhere in your application, use the following:

App::abort(404);

The abort method will immediately raise an exception which will be rendered by the exception handler. Optionally, you may provide the response text:

App::abort(403, 'Unauthorized action.');

This method may be used at any time during the request's lifecycle.

Custom error page

By default any errors will be shown with a detailed error page containing the file contents, line number and stack trace where the error occurred. You can display a custom error page by setting the configuration value debug to false in the config/app.php script and creating a page with the URL /error.

Logging

By default October is configured to create a single log file for your application which is stored in the storage/logs directory. You may write information to the logs using the Log facade:

$user = User::find(1);
Log::info('Showing user profile for user: '.$user->name);

The logger provides the eight logging levels defined in RFC 5424: emergency, alert, critical, error, warning, notice, info and debug.

Log::emergency($error);
Log::alert($error);
Log::critical($error);
Log::error($error);
Log::warning($error);
Log::notice($error);
Log::info($error);
Log::debug($error);

Contextual information

An array of contextual data may also be passed to the log methods. This contextual data will be formatted and displayed with the log message:

Log::info('User failed to login.', ['id' => $user->id]);

Helper functions

There are some global helper methods available to make logging easier. The trace_log function is an alias for Log::info with support for using arrays and exceptions as the message.

// Write a string value
$val = 'Hello world';
trace_log('The value is '.$val);

// Dump an array value
$val = ['Some', 'array', 'data'];
trace_log($val);

// Trace an exception
try {
    //
}
catch (Exception $ex) {
    trace_log($ex);
}

The trace_sql function enables database logging, when called it will log every command sent to the database. These records only appear in the system.log file and will not appear in the admininstration area log as this is stored in the database and would result in a feedback loop.

trace_sql();

Db::table('users')->count();

// select count(*) as aggregate from users

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