TYPO3 Core

I have an events extension with the following fields

date_start date NULL DEFAULT NULL,
date_end date NULL DEFAULT NULL,
time_start int(11) NULL DEFAULT NULL,
time_end int(11) NULL DEFAULT NULL,

The only required field is date_start so that it is possible to add events without defining a specific start time. The end time is rarely used anyway.

I want to be able to send both time fields with an empty value instead of '0' but that returns an SQL error on submitting the backend form when MySQL is in strict mode (and it clears the whole form, to boot). For the date_end field this works and will be stored as NULL. For now I go with the default value '0' and assume that '00:00' is an empty time field and no event starts at midnight – but that doesn’t feel right.

If this isn’t a TYPO3 bug and/or there is another way to achieve what I want, I apologise. But when adding a row via mysql> with empty values for the time fields they will be stored as NULL – just as I want it.

The TCA for the fields is

'date_start' => [
    'exclude' => true,
    'l10n_mode' => 'exclude',
    'label' => '' . $locLang . 'events.date_start',
    'config' => [
        'dbType' => 'date',
        'type' => 'input',
        'renderType' => 'inputDateTime',
        'size' => 7,
        'eval' => 'date, required',
        'default' => NULL
    ],
],
'date_end' => [
    'exclude' => true,
    'l10n_mode' => 'exclude',
    'label' => '' . $locLang . 'events.date_end',
    'config' => [
        'dbType' => 'date',
        'type' => 'input',
        'renderType' => 'inputDateTime',
        'size' => 7,
        'eval' => 'date',
        'default' => NULL
    ],
],
'time_start' => [
    'exclude' => true,
    'l10n_mode' => 'exclude',
    'label' => '' . $locLang . 'events.time_start',
    'config' => [
        'type' => 'input',
        'renderType' => 'inputDateTime',
        'size' => 4,
        'eval' => 'time',
        'default' => 0,
    ]
],
'time_end' => [
    'exclude' => true,
    'l10n_mode' => 'exclude',
    'label' => '' . $locLang . 'events.time_end',
    'config' => [
        'type' => 'input',
        'renderType' => 'inputDateTime',
        'size' => 4,
        'eval' => 'time',
        'default' => 0,
    ]
],