TYPO3: add maxitems = 1 to an image selection for a backend module - typo3

Question

I use the following code to make an image selection available in the backend:
(TYPO3 docs - inline - File Abstraction Layer)
'image' => [
'label' => 'LLL:EXT:lang/locallang_general.xlf:LGL.images',
'config' => \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::getFileFieldTCAConfig(
'image',
[
'appearance' => [
'createNewRelationLinkTitle' => 'LLL:EXT:cms/locallang_ttc.xlf:images.addFileReference'
],
// custom configuration for displaying fields in the overlay/reference table
// to use the image overlay palette instead of the basic overlay palette
'overrideChildTca' => [
'types' => [
'0' => [
'showitem' => '
--palette--;LLL:EXT:lang/locallang_tca.xlf:sys_file_reference.imageoverlayPalette;imageoverlayPalette,
--palette--;;filePalette'
],
\TYPO3\CMS\Core\Resource\File::FILETYPE_TEXT => [
'showitem' => '
--palette--;LLL:EXT:lang/locallang_tca.xlf:sys_file_reference.imageoverlayPalette;imageoverlayPalette,
--palette--;;filePalette'
],
],
],
],
$GLOBALS['TYPO3_CONF_VARS']['GFX']['imagefile_ext']
),
],
I want to limit the selection to 1 item which should be:
TYPO3 dosc - maxitems option
image => [
'config' => [
'maxitems' => 1,
],
],
I cannot find how to add that ... all I tried gives errors

Answer 1

Sometimes, you just have to find the matching part of documentation...
File abstraction layer (FAL)
The API call is \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::getFileFieldTCAConfig(). The first argument is the name of the current field, the second argument is an override configuration array, (...)
So it should do with overriding a part of the generated configuration by:
'image' => [
'label' => 'LLL:EXT:lang/locallang_general.xlf:LGL.images',
'config' => \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::getFileFieldTCAConfig(
'image',
[
'maxitems' => 1
]
)
]