Contao 4.10: DCA metaFields with fileTree

I need the possibility to link images with audio files in the file management. I followed this tutorial and the field is created, but only as a simple input field. https://docs.contao.org/dev/reference/dca/fields/#meta-wizard-fields

Then i added a standard DCA setup

<?php
  $GLOBALS['TL_DCA']['tl_files']['fields']['meta']['eval']['metaFields']['audiolink'] = [
     'inputType' => 'fileTree',
     'eval' => ['filesOnly' => true, 'fieldType' => 'radio', 'mandatory' => false],
     'sql' => ['type' => 'string', 'length' => 255, 'default' => ''],
  ];

but this does not work.

With this i get the Page Tree Wizard

<?php
 $GLOBALS['TL_DCA']['tl_files']['fields']['meta']['eval']['metaFields']['audiolink'] = [
    'attributes' => 'maxlength="255"', 'dcaPicker' => true
 ];

Then i tried this

<?php
  $GLOBALS['TL_DCA']['tl_files']['fields']['meta']['eval']['metaFields']['audiolink'] = [
     'attributes' => 'maxlength="255"', 'fileTree' => true
  ];

but this does not work, too. So how to get the "fileTree" Wizard working at file management?

Solution

You can't, the meta wizard supports only text fields (and textarea fields since Contao 4.9.10).

Instead of using tl_files.meta, you could add an additional field to tl_files:

// contao/dca/tl_files.php
use Contao\CoreBundle\DataContainer\PaletteManipulator;

$GLOBALS['TL_DCA']['tl_files']['fields']['foobar'] = [
    'inputType' => 'fileTree',
    'eval' => ['filesOnly' => true, 'fieldType' => 'radio', 'mandatory' => false],
    'sql' => "binary(16) NULL"
];

PaletteManipulator::create()
    ->addField('foobar', null)
    ->applyToPalette('default', 'tl_files')
;

However, this of course means that you can select this file only per file and not per language per file.