Feature: #105549 - Support qualified and unqualified ISO8601 dates in DataHandler 

Description 

The DataHandler API has been extended to support both qualified and unqualified ISO 8601 date formats, correctly handling supplied timezone offsets when provided.

Qualified ISO 8601

Includes an explicit timezone offset (for example, 1999-12-11T10:09:00+01:00 or 1999-12-11T10:09:00Z)

Unqualified ISO 8601

Omits timezone offsets, representing LOCALTIME (for example, 1999-12-11T10:09:00)

The DataHandler now accepts five different formats:

The ISO 8601 variants and \DateTimeInterface objects are intended for use in the public API. The SQL-flavored variant and Unix timestamps are primarily intended for internal operations such as copy or import processes involving native DATETIME and INT timestamp database fields.

$myDate = new \DateTime('yesterday');
$this->dataHandler->start([
    'tx_myextension_mytable' => [
        'NEW-1' => [
            'pid' => 2,
            // Format as LOCALTIME
            'mydatefield_1' => $myDate->format('Y-m-d\\TH:i:s'),
            // Format with timezone information
            // (offsets will be normalized to the persistence timezone format,
            // UTC for integer fields, LOCALTIME for native DATETIME fields)
            'mydatefield_2' => $myDate->format('c'),
            // Pass \DateTimeInterface objects directly
            'mydatefield_3' => $myDate,
        ],
    ],
]);

Impact 

TYPO3 now provides accurate and consistent handling of ISO 8601 dates, eliminating previous issues related to timezone interpretation and LOCALTIME representation.