Custom Backend Template breaks content columns

[mkrappitz]

When using a custom fluid backend template with the method setBackendTemplate() (https://github.com/b13/container/blob/master/README.md#methods-of-the-containerconfiguration-object), the content of the custom backend fluid template is being outputted in the page module, but the grid for placing content elements is not being shown. This happened after updating to container 3.1.0 on TYPO3 version 13.4.1. Before we used container version 1 and 2 on TYPO3 version 12 and the same backehnd template had no problems. Is this is a bug or is there a syntax change necessary? The documentation unfortunately says nothing about that topic.

[the-andyman]

I have the same problem.
{tx_container_grid -> f:format.raw()}
no longer displays anything.

[TheSophiaDev]

I had the same problem and debugged it.

TYPO3 throws a PageContentPreviewRenderingEvent in the typo3/cms-backend/Classes/View/BackendLayout/Grid/GridColumnItem class. If the previewContent variable is not null after the EventListener has been executed, the actual PreviewRenderer (in this case ContainerPreviewRenderer) is no longer executed with the renderPageModulePreviewContent() function. This function is necessary to show the grid content in the backend preview.

TYPO3 itself has an EventListener for this event, namely the typo3/cms-backend/Classes/Preview/FluidBasedContentPreviewRenderer. If a backend template is stored in the TsConfig, it fills the previewContent variable with the content of this template. The setBackendTemplate() function stores the template in the TsConfig. Therefore the variable previewContent of the event is always filled after the execution of the EventListener typo3/cms-backend/Classes/Preview/FluidBasedContentPreviewRenderer if a backend template has been stored and no own PreviewRenderer is executed anymore. My current solution for this problem is also to register an EventListener for the event, which is executed after the FluidBasedContentPreviewRenderer and to execute the ContainerPreviewRenderer with all information.

Maybe this is a solution for you too.

[kauz56]

Also having this issue. It should be noted that this seems to be an incompatibility with TYPO3 13. The same version of container (3.1.1) doesn't have this issue with TYPO3 12.