TYPO3 - Add flexform to my own extension - fluid

Question

I am building my own extension.
I have found this page about adding Flexform to the Extension
https://gist.github.com/alrnz/c0f00b196d378f5b9150
And in my ext_tables.php i have this:
\TYPO3\CMS\Extbase\Utility\ExtensionUtility::registerPlugin(
$_EXTKEY,
'Xlsxtotables',
'XLSX to tables'
);
// Include flex forms
$pluginSignature = str_replace('_', '', $_EXTKEY) . '_' . 'xlsxtotables'; // from registerPlugin(...)
$TCA['tt_content']['types']['list']['subtypes_addlist'] [$pluginSignature] = 'pi_flexform';
\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addPiFlexFormValue(
$pluginSignature,
'FILE:EXT:' . $_EXTKEY . '/Configuration/FlexForms/flexform_xlsxtotables.xml'
);
I know that the XML-file is in the right place, but I do not get anyting from it in TYPO3 backend.
Any suggestions?

Answer 1

Try replace
$pluginSignature = str_replace('_', '', $_EXTKEY) . '_' . 'xlsxtotables';
by
$extensionName = strtolower(\TYPO3\CMS\Core\Utility\GeneralUtility::underscoredToUpperCamelCase($_EXTKEY));
$pluginSignature = $extensionName.'_'.'xlsxtotables';
And dont forget to empty your general cache before you see a change with your flexform.

Answer 2

You can try below code in ext_tables.php file
$pluginName = 'Pi1'; // Give Your Plugin Nmae
$pluginSignature = preg_replace('/[^a-z0-9]/', '', strtolower($_EXTKEY)) . '_' . strtolower($pluginName);
// FlexForm configuration
$TCA['tt_content']['types']['list']['subtypes_addlist'][$pluginSignature] = 'pi_flexform';
\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addPiFlexFormValue(
$pluginSignature,
'FILE:EXT:' . $_EXTKEY . '/Configuration/FlexForms/flexformname.xml'
);
For Adding Flexforms in One or More Front-end plugins you can use Below code in ext_tables.php
$extensionName = \TYPO3\CMS\Core\Utility\GeneralUtility::underscoredToUpperCamelCase($_EXTKEY);
$frontendpluginName = 'xxx'; //Your Front-end Plugin Name
$pluginSignature = strtolower($extensionName) . '_'.strtolower($frontendpluginName);
$GLOBALS['TCA']['tt_content']['types']['list']['subtypes_addlist'][$pluginSignature] = 'pi_flexform';
\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addPiFlexFormValue($pluginSignature, 'FILE:EXT:' . $_EXTKEY . '/Configuration/FlexForms/xyz.xml');