Feature: #57082 - New TCA type "language"

See forge#57082

Description

A new TCA field type called language has been added to TYPO3 Core. Its main purpose is to simplify the TCA language configuration. It therefore supersedes the special=languages option of TCA columns with type=select as well as the now mis-use of the foreign_table option, being set to sys_language.

Since the introduction of site configurations and the corresponding site languages back in v9, the sys_language table was not longer the only source of truth regarding available languages. The languages available for a record are defined by the associated site configuration.

Therefore, the new field allows to finally decouple the available site languages from the sys_language table. This effectively reduces quite an amount of code and complexity, since no relations have to be fetched and processed anymore. This also makes the sys_refindex table a bit smaller, since no entries have to be added for this relation anymore. To clean up your existing reference index, you might use the CLI command bin/typo3 referenceindex:update.

Another pain point was the special -1 language which always had to be added to each TCA configuration manually. Thus, a lot of different implementations of this special case could be found in one and the same TYPO3 installation.

The new TCA type now automatically displays all available languages for the current context (the corresponding site configuration) and also automatically adds the special -1 language for all record types, except pages.

// Before

'config' => [
   'type' => 'select',
   'renderType' => 'selectSingle',
   'foreign_table' => 'sys_language',
   'items' => [
      ['LLL:EXT:core/Resources/Private/Language/locallang_general.xlf:LGL.allLanguages', -1],
      ['LLL:EXT:core/Resources/Private/Language/locallang_general.xlf:LGL.default_value', 0]
   ],
   'default' => 0
]

// After

'config' => [
   'type' => 'language'
]
Copied! 
// Before

'config' => [
   'type' => 'select',
   'renderType' => 'selectSingle',
   'special' => 'languages',
   'items' => [
      [
         'LLL:EXT:core/Resources/Private/Language/locallang_general.xlf:LGL.allLanguages',
         -1,
         'flags-multiple'
      ],
   ],
   'default' => 0,
]

// After

'config' => [
   'type' => 'language'
]
Copied!

Since the new TCA type is mostly based on the type=select internally, most of the associated TCA and TSconfig options can still be applied. This includes e.g. the selectIcons field wizard, as well as the keepItems and removeItems page TSconfig options.

In records on root level ( pid=0) or on a page, outside of a site context, all languages from all site configurations are displayed in the new field.

An automatic TCA migration is performed on the fly, migrating all occurrences to the new TCA type and triggering a PHP E_USER_DEPRECATED error where code adaption has to take place. Columns defined as $TCA['ctrl']['languageField'], as well as all columns using the special=languages option in combination with type=select are affected.

Note that the migration resets the whole config array to use the new TCA type. Custom setting such as field wizards are not evaluated until the TCA configuration is adapted.