[TYPO3-mvc] unset relation

[Peter Niederlag]

Hello,

considering this simple (optional) n:1 relation

tx_foo_dm_a {
   b = tx_foo_dm_b
}

Is there any "out-of-the-box" solution that enables me to unset the 
relation when submitting tx_foo_dm_a?

Submitting an tx_foo_dm_a.b = '' or '0 ' leads to keeping the old value....

Greets and thx,
Peter
-- 
Peter Niederlag
http://www.niekom.de * TYPO3 & EDV Dienstleistungen *