Storing the changes

There are various ways to store changes to $GLOBALS['TCA']. They depend - partly - on what you are trying to achieve and - a lot - on the version of TYPO3 CMS which you are targeting.

There are two main ways to store your changes to the TCA: inside an extension or straight in the typo3conf folder. Both are described below in more details.

Storing in extensions

The advantage of putting your changes inside an extension is that they are nicely packaged in a self-contained entity which can be easily deployed on multiple servers.

The drawback is that the extension loading order must be finely controlled. Indeed if your extension modifies another extension, your extension must be loaded after the extension you are modifying. This can be achieved by registering that other extension as a dependency of yours. See the description of constraints in Core APIs.

For more information about an extension's structure, please refer to the extension architecture chapter in Core APIs.

Storing in ext_tables.php files

Until TYPO3 CMS 6.1 (still supported for 6.2) changes to $GLOBALS['TCA'] are packaged into an extension's ext_tables.php file. This is strongly discouraged in more recent versions of TYPO3 CMS.

Storing in the Overrides folder

Since TYPO3 CMS 6.2 (6.2.1 to be precise) changes to $GLOBALS['TCA'] must be stored inside a folder called Configuration/TCA/Overrides with one file per modified table. These files are named along the pattern <tablename>.php.

Thus if you want to customize the TCA of tx_foo_domain_model_bar, you'd create the file Configuration/TCA/Overrides/tx_foo_domain_model_bar.php.

The advantage of this method is that all such changes are incorporated into $GLOBALS['TCA'] before it is cached. This is thus far more efficient.

Important

Be aware that you cannot extend the TCA of extensions if it was configured within its ext_tables.php file, usually containing the "ctrl" section referencing a "dynamicConfigFile". Please ask the extension author to switch to the Configuration/TCA/<tablename>.php setup.

Important

Only TCA-related changes should go into Configuration/TCA/Overrides files. Some API calls may be okay as long as they also manipulate only $GLOBALS['TCA']. For example, it is fine to register a plugin with \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addPlugin() in Configuration/TCA/Overrides/tt_content.php because that API call only modifies $GLOBALS['TCA'] for table "tt_content".

Changing the TCA "on the fly"

It is also possible to perform some special manipulations on $GLOBALS['TCA'] right before it is stored into cache, thanks to the tcaIsBeingBuilt signal. This signal was introduced in TYPO3 CMS 6.2.1.