# Zend_Controller_Plugin_ErrorHandler

`Zend_Controller_Plugin_ErrorHandler` provides a drop-in plugin for handling exceptions thrown by your application, including those resulting from missing controllers or actions; it is an alternative to the methods listed in the MVC Exceptions section.

The primary targets of the plugin are:

- Intercept exceptions raised when no route matched

- Intercept exceptions raised due to missing controllers or action methods

- Intercept exceptions raised within action controllers

In other words, the ErrorHandler plugin is designed to handle HTTP 404-type errors (page missing) and 500-type errors (internal error). It is not intended to catch exceptions raised in other plugins.

By default, `Zend_Controller_Plugin_ErrorHandler` will forward to `ErrorController::errorAction()` in the default module. You may set alternate values for these by using the various accessors available to the plugin:

- `setErrorHandlerModule()` sets the controller module to use.

- `setErrorHandlerController()` sets the controller to use.

- `setErrorHandlerAction()` sets the controller action to use.

- `setErrorHandler()` takes an associative array, which may contain any of the keys 'module', 'controller', or 'action', with which it will set the appropriate values.

Additionally, you may pass an optional associative array to the constructor, which will then proxy to `setErrorHandler()`.

`Zend_Controller_Plugin_ErrorHandler` registers a `postDispatch()` hook and checks for exceptions registered in the response object. If any are found, it attempts to forward to the registered error handler action.

If an exception occurs dispatching the error handler, the plugin will tell the front controller to throw exceptions, and rethrow the last exception registered with the response object.

## Using the ErrorHandler as a 404 Handler

Since the ErrorHandler plugin captures not only application errors, but also errors in the controller chain arising from missing controller classes and/or action methods, it can be used as a 404 handler. To do so, you will need to have your error controller check the exception type.

Exceptions captured are logged in an object registered in the request. To retrieve it, use `Zend_Controller_Action::_getParam('error_handler')`:

    class ErrorController extends Zend_Controller_Action
    {
        public function errorAction()
        {
            $errors = $this->_getParam('error_handler');
        }
    }

Once you have the error object, you can get the type via `$errors->type;`. It will be one of the following:

- `Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_ROUTE`, indicating no route matched.

- `Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_CONTROLLER`, indicating the controller was not found.

- `Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_ACTION`, indicating the requested action was not found.

- `Zend_Controller_Plugin_ErrorHandler::EXCEPTION_OTHER`, indicating other exceptions.

You can then test for either of the first three types, and, if so, indicate a 404 page:

    class ErrorController extends Zend_Controller_Action
    {
        public function errorAction()
        {
            $errors = $this->_getParam('error_handler');

            switch ($errors->type) {
                case Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_ROUTE:
                case Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_CONTROLLER:
                case Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_ACTION:
                    // 404 error -- controller or action not found
                    $this->getResponse()
                         ->setRawHeader('HTTP/1.1 404 Not Found');

                    // ... get some output to display...
                    break;
                default:
                    // application error; display error page, but don't
                    // change status code
                    break;
            }
        }
    }

Finally, you can retrieve the exception that triggered the error handler by grabbing the exception property of the error_handler object:

    public function errorAction()
    {
            $errors = $this->_getParam('error_handler');

            switch ($errors->type) {
                case Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_ROUTE:
                case Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_CONTROLLER:
                case Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_ACTION:
                    // 404 error -- controller or action not found
                    $this->getResponse()
                         ->setRawHeader('HTTP/1.1 404 Not Found');

                    // ... get some output to display...
                    break;
                default:
                    // application error; display error page, but don't change
                    // status code

                    // ...

                    // Log the exception:
                    $exception = $errors->exception;
                    $log = new Zend_Log(
                        new Zend_Log_Writer_Stream(
                            '/tmp/applicationException.log'
                        )
                    );
                    $log->debug($exception->getMessage() . "\n" .
                                $exception->getTraceAsString());
                    break;
            }
    }

## Handling Previously Rendered Output

If you dispatch multiple actions in a request, or if your action makes multiple calls to `render()`, it's possible that the response object already has content stored within it. This can lead to rendering a mixture of expected content and error content.

If you wish to render errors inline in such pages, no changes will be necessary. If you do not wish to render such content, you should clear the response body prior to rendering any views:

    $this->getResponse()->clearBody();

## Plugin Usage Examples

### Standard Usage

    $front = Zend_Controller_Front::getInstance();
    $front->registerPlugin(new Zend_Controller_Plugin_ErrorHandler());

### Setting a Different Error Handler

    $front = Zend_Controller_Front::getInstance();
    $front->registerPlugin(new Zend_Controller_Plugin_ErrorHandler(array(
        'module'     => 'mystuff',
        'controller' => 'static',
        'action'     => 'error'
    )));

### Using Accessors

    $plugin = new Zend_Controller_Plugin_ErrorHandler();
    $plugin->setErrorHandlerModule('mystuff')
           ->setErrorHandlerController('static')
           ->setErrorHandlerAction('error');

    $front = Zend_Controller_Front::getInstance();
    $front->registerPlugin($plugin);

## Error Controller Example

In order to use the Error Handler plugin, you need an error controller. Below is a simple example.

    class ErrorController extends Zend_Controller_Action
    {
        public function errorAction()
        {
            $errors = $this->_getParam('error_handler');

            switch ($errors->type) {
                case Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_ROUTE:
                case Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_CONTROLLER:
                case Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_ACTION:
                    // 404 error -- controller or action not found
                    $this->getResponse()->setRawHeader('HTTP/1.1 404 Not Found');

                    $content =<<<EOH
    <h1>Error!</h1>
    <p>The page you requested was not found.</p>
    EOH;
                    break;
                default:
                    // application error
                    $content =<<<EOH
    <h1>Error!</h1>
    <p>An unexpected error occurred. Please try again later.</p>
    EOH;
                    break;
            }

            // Clear previous content
            $this->getResponse()->clearBody();

            $this->view->content = $content;
        }
    }