Invalid custom formengine element causing persistence issue in TYPO3 backend
TL;DR: Always make sure, that a custom TYPO3 formengine element returns valid HTML in
Some days ago I stumbled across this issue on TYPO3 forge with the title “TCA IRRE does not save, maybe if there are to many objects”. Since I also use inline elements in my extensions and I never experienced the reported problem, I was in doubt, that the problem was related to TYPO3 core, since TYPO3 has not any hard limit for the amount of inline records.
As the issue description was very detailled and the reporter even attached an extension to test the scenario, I took some time to analyse the problem.
First I could not really reproduce the problem and assumed, that it maybe was related to PHP
on the server the website was running. But it came out, that this was not the reason for the problem, since the
max_input_vars to a very high value and the problem was still present.
I then again tried to reproduce the problem and this time I was successful. I did not even add many inline elements as suggested in the report, but only added a few elements. So the problem could not be related to the amount of inline elements at all. I therefore checked the TCA of the affected records and noticed, that a custom formengine element was in use in the main record. After I removed the custom formengine element, the problem was gone.
I was however interested in, why the element caused the described problem. After debugging some time, I found out,
doSave was not set to
1, when the custom formengine element was in the TCA. Since the
element must in some way be invalid. After my analysis, I found the following 2 errors with the element.
The first problem with the element was, that it used
'type' => 'select' but without actually holding an input field
for a value. Formengine only has one single type, where no database field is required and that is the
The second problem was somehow hard to spot, but it was the main reason why new inline elements at some point were
not persisted anymore. The HTML markup in
$resultArray['html'] of the custom formengine element was not valid HTML.
The HTML contained too many closing
div elements, which resulted in the whole structure of the TYPO3 backend form
formengine was not able to fully validate the form anymore and therefore finally did not set
in changes not being saved.
As a result of the analysis, I created a pull request for the TYPO3 documentation to outline, that custom formengine elements must always return valid HTML to avoid unexpected behavior in TYPO3 backend.