.. include:: /Includes.rst.txt .. _flash-messages: Flash messages ============== There exists a generic system to show users that an action was performed successfully, or more importantly, failed. This system is known as "flash messages". The screenshot below shows the various severity levels of messages that can be emitted. .. figure:: ../../Images/FlashMessagesAll.png :alt: All levels of flash messages The "examples" BE module shows one of each type of flash message The different severity levels are described below: - *Notifications* are used to show very low severity information. Such information usually is so unimportant that it can be left out, unless running in some kind of debug mode. - *Information messages* are to give the user some information that might be good to know. - *OK messages* are to signal a user about a successfully executed action. - *Warning messages* show a user that some action might be dangerous, cause trouble or might have partially failed. - *Error messages* are to signal failed actions, security issues, errors and the like. .. _flash-messages-api: Flash messages API ------------------ Creating a flash message is achieved by simply instantiating an object of class :php:`\TYPO3\CMS\Core\Messaging\FlashMessage`:: $message = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Core\Messaging\FlashMessage::class, 'My message text', 'Message Header', // [optional] the header \TYPO3\CMS\Core\Messaging\FlashMessage::WARNING, // [optional] the severity defaults to \TYPO3\CMS\Core\Messaging\FlashMessage::OK true // [optional] whether the message should be stored in the session or only in the \TYPO3\CMS\Core\Messaging\FlashMessageQueue object (default is false) ); Flash messages severities ^^^^^^^^^^^^^^^^^^^^^^^^^ The severity is defined by using class constants provided by :php:`\TYPO3\CMS\Core\Messaging\FlashMessage`: - :php:`\TYPO3\CMS\Core\Messaging\FlashMessage::NOTICE` for notifications - :php:`\TYPO3\CMS\Core\Messaging\FlashMessage::INFO` for information messages - :php:`\TYPO3\CMS\Core\Messaging\FlashMessage::OK` for success messages - :php:`\TYPO3\CMS\Core\Messaging\FlashMessage::WARNING` for warnings - :php:`\TYPO3\CMS\Core\Messaging\FlashMessage::ERROR` for errors The fourth parameter passed to the constructor is a flag that indicates whether the message should be stored in the session or not (the default is not). Storage in the session should be used if you need the message to be still present after a redirection. In backend modules you can then make that message appear on top of the module after a page refresh or the rendering of the next page request or render it on your own where ever you want. This example adds the flash message at the top of modules when rendering the next request:: $flashMessageService = $this->objectManager->get(\TYPO3\CMS\Core\Messaging\FlashMessageService::class); $messageQueue = $flashMessageService->getMessageQueueByIdentifier(); $messageQueue->addMessage($message); The message is added to the queue and then the template class calls :php:`\TYPO3\CMS\Core\Messaging\FlashMessageQueue::renderFlashMessages()` which renders all messages from the queue. Here's how such a message looks like in a module: .. figure:: ../../Images/FlashMessagesExample.png :alt: A flash message in action A typical (success) message shown at the top of a module By default flash messages are shown atop the content of a module. However, if needed, you can change where the messages are shown by manipulating a module's template and inserting the :html:`###FLASHMESSAGES###` marker. Messages will then replace that marker instead of appearing at the top of the module. The recommend way is to use the fluid ViewHelper :html:``. This ViewHelper works in any context because it use the :php:`FlashMessageRendererResolver` class to find the correct renderer for the current context. .. _flash-messages-renderer: Flash messages renderer ----------------------- The implementation of rendering FlashMessages in the core has been optimized. A new class called :php:`FlashMessageRendererResolver` has been introduced. This class detects the context and renders the given FlashMessages in the correct output format. It can handle any kind of output format. The core ships with the following FlashMessageRenderer classes: * :php:`TYPO3\CMS\Core\Messaging\Renderer\BootstrapRenderer` This renderer is used by default in the TYPO3 backend. The output is based on Bootstrap markup * :php:`TYPO3\CMS\Core\Messaging\Renderer\ListRenderer` This renderer is used by default in the TYPO3 frontend. The output is a simple