TYPO3 Core

I'm not sure this was ever possible in TYPO3, or I suspect that it was not the same use case (e.g. hidden field existed, one radio had been checked, form data was not as expected, etc) - or at least, I'm not sure it was ever intended to be possible with the rewritten property mapper (that replaces the old, deprecated and removed one). In any case, speaking solely from the current status of things, it looks like this is by design. Each radio button is rendered individually indicating that if you wish a default value to be posed, you have two equally valid ways:

• Manually render an f:form.hidden before the radios.
• Set one of the radios' "checked" attribute to "checked".

The former may be simpler to implement but the latter would cause less HTML to be generated; both will apply with direct "name" attributes and "property" on objects. Use whichever one you feel applies best ;)

I will take the liberty of closing this issue since there are two ways to get the result and no changes are required in the source code.