O Guia Definitivo do Yii 1.1

Yii defines two exception classes: CException and CHttpException. The former is a
generic exception class, while the latter represents an exception that should be displayed
to end users. The latter also carries a statusCode property representing an HTTP status
code. The class of an exception determines how it should be displayed, as we will explain
next.
Tip: Raising a CHttpException exception is a simple way of reporting errors caused by
user misoperation. For example, if the user provides an invalid post ID in the URL, we
can simply do the following to show a 404 error (page not found):
// if post ID is invalid
throw new CHttpException(404,'The specified post cannot be found.');
Displaying Errors
When an error is forwarded to the CErrorHandler application component, it chooses an
appropriate view to display the error. If the error is meant to be displayed to end users,
such as a CHttpException, it will use a view named errorXXX, where XXX stands for the
HTTP status code (e.g. 400, 404, 500). If the error is an internal one and should only be
displayed to developers, it will use a view named exception. In the latter case, complete
call stack as well as the error line information will be displayed.
Info: When the application runs in production mode, all errors including those internal
ones will be displayed using view errorXXX. This is because the call stack of an error
may contain sensitive information. In this case, developers should rely on the error logs
to determine what is the real cause of an error.
CErrorHandler searches for the view file corresponding to a view in the following order:
• WebRoot/themes/ThemeName/views/system: this is the system view directory under
the currently active theme.
• WebRoot/protected/views/system: this is the default system view directory for an
application.
• yii/framework/views: this is the standard system view directory provided by the Yii
framework.
Therefore, if we want to customize the error display, we can simply create error view files
under the system view directory of our application or theme. Each view file is a normal
PHP script consisting of mainly HTML code. For more details, please refer to the default
view files under the framework's view directory.
Handling Errors Using an Action
Starting from version 1.0.6, Yii allows using a controller action to handle the error display
work. To do so, we should configure the error handler in the application configuration as
follows: