Error handling

1. Introduction

The framework features the errorHandler function, that is intended to do global error handling. This function is used to catch and handle errors at a central place. For this reason, it uses a ErrorHandler component, that can be configured within the registry. The error handler itself is then responsible for the handling of the current error.

The preconfigured APF error handler saves the error message into a log file and displays the nice error screen including the stacktrace. Details can be taken from the API documentation of the DefaultErrorHandler class.


2. Configuration

To replace the preconfigured DefaultErrorHandler with an own class, the registry offset ErrorHandler within the apf::core namespace must be filled with the desired ErrorHandlerDefinition instance. The configuration of the error handling component must be placed in the bootstrap file directly after the pagecontroller.php is included.

The definition of a custom error handler looks as follows:
PHP-Code
$reg = &Singleton::getInstance('Registry'); $reg->register( 'apf::core', 'ErrorHandler', new ErrorHandlerDefinition( 'my::errorhandler::namespace', 'MyErrorHandler' ) );
As you can take from the example, the desired ErrorHandler is referenced by it's namespace and it's class name.

Note: if the registry offset does not contain a valid definition, the errors are displayed in text mode. You can identify the fallback mode by the prefix
APF-Template
APF catchable error:
In this cases, the definition or the implementation of the error handler class must be checked.

In order to deactivate the ErrorHandler, initilize the registry offset with null.



3. Enhancement

To introduce a custom error handling, you must implement the AbstractErrorHandler. This class defines the following interface:
PHP-Code
class AbstractErrorHandler extends coreObject { function handleError($errorNumber,$errorMessage,$errorFile,$errorLine){ } }
If an error occures, the handleError is applied the following parameters:
  • error number
  • error message
  • filename where the error occures
  • line where the error occures
Due to the fact, that the error handling is done in an page controller independent class, that is not created by the service manager, the current Context and the current Language are not available!

If these information are important for the error handling, the must be obtained from information containers available within an application or module (e.g. application model class). The environment param is available via the registry as mentioned in the corresponding documentation chapter.


4. Usage

The global error handling mechanism can be used by calling the PHP function
PHP-Code
trigger_error();
Details on the usage of the function can be taken from the online documentation under http://php.net/trigger_error.


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