[TYPO3] default => NULL

[André Esch]

Hello,

I do have a Problem creating a Extension. I need to have a
date-field which will be filled with NULL if it is empty or the
checkbox is unchecked.

Something like that:
in the tca-file of the extension:

"feInterface" => $TCA["tx_Vorschau_filme"]["feInterface"],
 "columns" => Array (
    "startdatum" => Array (
       "exclude" => 1,
       "label" => 
"LLL:EXT:Vorschau/locallang_db.php:tx_Vorschau_filme.startdatum",
       "config" => Array (
            "type" => "input",
            "size" => "8",
            "max" => "20",
            "eval" => "date",
            "checkbox" => NULL,
            "default" => NUL,
   )
  ),

This doesn't work. Is there another way?

Kind reguards from Germany
André