Radio buttons 

Default value set if a new record is created. If empty, no radio gets selected.

For details see fieldControl.

For details see fieldInformation.

An array of values which can be selected.

Each entry is in itself an associative array.

label (plain text label or label reference)

The displayed title.

value (integer or string)

The value stored in the database.

An array with numerical keys that can contain item processors implementing ItemsProcessorInterface .

Each item processor is executed sequentially based on its numerical array key. The item processor can add, modify or remove items from the SelectItemCollection , influencing which items are displayed.

<?php

use MyVendor\MyExtension\Backend\ItemsProcessor\SpokenLanguageItemsProcessor;
use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;

defined('TYPO3') or die();

ExtensionManagementUtility::addTCAcolumns('tx_myextension_talk', [
  'spoken_language' => [
    'label' => 'my_extension.db:talk.spoken_language',
    'config' => [
      'type' => 'radio',
      // Required for radio fields, the items come from the processor
      'items' => [],
      'itemsProcessors' => [
        100 => [
          'class' => SpokenLanguageItemsProcessor::class,
        ],
      ],
    ],
  ],
]);
ExtensionManagementUtility::addToAllTCAtypes(
  'tx_myextension_talk',
  'spoken_language',
  '',
  'after:abstract',
);

A SelectItem for a field of type radio must be of type radio and must provide a label and value. The value can be an integer or string.

<?php

declare(strict_types=1);

namespace MyVendor\MyExtension\Backend\ItemsProcessor;

use TYPO3\CMS\Core\DataHandling\ItemsProcessorContext;
use TYPO3\CMS\Core\DataHandling\ItemsProcessorInterface;
use TYPO3\CMS\Core\Schema\Struct\SelectItem;
use TYPO3\CMS\Core\Schema\Struct\SelectItemCollection;

/**
 * Offers the languages of the site as the language a talk is held in
 */
final readonly class SpokenLanguageItemsProcessor implements ItemsProcessorInterface
{
  public function processItems(
    SelectItemCollection $items,
    ItemsProcessorContext $context,
  ): SelectItemCollection {
    foreach ($context->site->getLanguages() as $language) {
      $items->add(new SelectItem(
        type: 'radio',
        label: $language->getTitle(),
        value: $language->getLocale()->getLanguageCode(),
      ));
    }
    return $items;
  }
}

See also Item processor registration and implementation

PHP method which is called to fill or manipulate the items array. It is recommended to use the actual FQCN with class and then concatenate the method:

\MyVendor\MyExtension\UserFunction\FormEngine\YourClass::class . '->yourMethod'

This becomes handy when using an IDE and doing operations like renaming classes.

The provided method will have an array of parameters passed to it. The items array is passed by reference in the key items. By modifying the array of items, you alter the list of items. A method may throw an exception which will be displayed as a proper error message to the user.

• items (passed by reference)
• config (TCA config of the field)
• TSconfig (The matching itemsProcFunc TSconfig)
• table (current table)
• row (current database record)
• field (current field name)
• effectivePid (correct page ID)
• site (current site)

The following parameter only exists if the field has a flex parent.

• flexParentDatabaseRow

The following parameters are filled if the current record has an inline parent:

• inlineParentUid
• inlineParentTableName
• inlineParentFieldName
• inlineParentConfig
• inlineTopMostParentUid
• inlineTopMostParentTableName
• inlineTopMostParentFieldName

Renders the field in a way that the user can see the value but cannot edit it.