TYPO3 how to redeclare FrontendUser class - typo3

Question

I have TYPO3 7.6.18. I need to redeclare TYPO3\CMS\Extbase\Domain\Model\FrontendUser class and extend it with my new class Fhk\Feusersplus\Domain\Model\FrontendUser. I need that TYPO3 use my FrontEnd class. (I need add new upload field)
I tried:
ext_typoscript_setup.txt:
config.tx_extbase{
persistence{
classes{
In2code\Femanager\Domain\Model\User {
subclasses {
0 = Fhk\Feusersplus\Domain\Model\User
}
}
TYPO3\CMS\Extbase\Domain\Model\FrontendUser{
subclasses {
0 = Fhk\Feusersplus\Domain\Model\FrontendUser
}
}
Fhk\Feusersplus\Domain\Model\User {
mapping {
tableName = fe_users
recordType = 0
}
}
}
}
objects {
In2code\Femanager\Controller\NewController.className = Fhk\Feusersplus\Controller\NewController
In2code\Femanager\Controller\EditController.className = Fhk\Feusersplus\Controller\EditController
In2code\Femanager\Controller\UserController.className = Fhk\Feusersplus\Controller\UserController
#Kennziffer\KeQuestionnaire\Domain\Repository\ResultRepository.className = Fhk\Feusersplus\Domain\Repository\ResultRepository
}
}
ext_localconf.php
$GLOBALS['TYPO3_CONF_VARS']['SYS']['Objects']['TYPO3\CMS\Extbase\Domain\Model\FrontendUser'] = array(
'className' => 'Fhk\Feusersplus\Domain\Model\FrontendUser'
);
But I have error:
Exception while property mapping at property path "": Property "backgroundimage" was not found in target object of type "Fhk\Feusersplus\Domain\Model\User".
my file ext:Configuration/TCA/Overrides/fe_users.php
$tmp_feusersplus_columns = array(
'backgroundimage' => [
'exclude' => 1,
'label' => 'Background image',
'config' => \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::getFileFieldTCAConfig(
'image', [
'appearance' => [
'createNewRelationLinkTitle' => 'LLL:EXT:cms/locallang_ttc.xlf:images.addFileReference'
],
'maxitems' => 1,
// custom configuration for displaying fields in the overlay/reference table
// to use the imageoverlayPalette instead of the basicoverlayPalette
'foreign_match_fields' => [
'fieldname' => 'backgroundimage',
'tablenames' => 'fe_users',
'table_local' => 'sys_file',
],
'foreign_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'
],
\TYPO3\CMS\Core\Resource\File::FILETYPE_IMAGE => [
'showitem' => '
--palette--;LLL:EXT:lang/locallang_tca.xlf:sys_file_reference.imageoverlayPalette;imageoverlayPalette,
--palette--;;filePalette'
],
\TYPO3\CMS\Core\Resource\File::FILETYPE_AUDIO => [
'showitem' => '
--palette--;LLL:EXT:lang/locallang_tca.xlf:sys_file_reference.imageoverlayPalette;imageoverlayPalette,
--palette--;;filePalette'
],
\TYPO3\CMS\Core\Resource\File::FILETYPE_VIDEO => [
'showitem' => '
--palette--;LLL:EXT:lang/locallang_tca.xlf:sys_file_reference.imageoverlayPalette;imageoverlayPalette,
--palette--;;filePalette'
],
\TYPO3\CMS\Core\Resource\File::FILETYPE_APPLICATION => [
'showitem' => '
--palette--;LLL:EXT:lang/locallang_tca.xlf:sys_file_reference.imageoverlayPalette;imageoverlayPalette,
--palette--;;filePalette'
]
]
], $GLOBALS['TYPO3_CONF_VARS']['GFX']['imagefile_ext'])
],
);
And yes, I extend ext_tables with backgroundimage field
It's seems that TYPO3 not use my new FrontendUser class.
Help me please anybody!

Answer 1

I don't think that there is a Problem with DB or TCA, most likely the property is just missing in your model Property "backgroundimage" was not found:
protected $backgroundimage = null;
public function getBackgroundimage()
{
return $this->backgroundimage;
}