BeforeFormEnginePageInitializedEvent 

The PSR-14 event \TYPO3\CMS\Backend\Controller\Event\BeforeFormEnginePageInitializedEvent allows to listen for before the form engine has been initialized (before all data will be persisted).

Example 

API 

class BeforeFormEnginePageInitializedEvent
Fully qualified name
\TYPO3\CMS\Backend\Controller\Event\BeforeFormEnginePageInitializedEvent

Event to listen to before the form engine has been initialized (= before all data will be persisted)

getController ( )
Returns
TYPO3CMSBackendControllerEditDocumentController
getRequest ( )
Returns
PsrHttpMessageServerRequestInterface