[TYPO3-mvc] Property mapping of m:n and n:1 related objects in a New.html form to create new object AND related objects?

[Roland]

hi everybody,

i try to setup a form to create an new object. there is one (for me) 
tricky thing:

the object has m:n relations and n:1 relations to other objects in the 
domain model. so i used <f:form.select /> and <f:form.checkbox /> in the 
fluid template to put selectboxes and checkboxes into the form.

how can i map theses form elements to object properties?

when i try something like this...

--- quote ---
<f:for each="{categories}" as="category">
<f:form.checkbox property="categories" value="{category}" />
</f:for>
--- /quote ---

...i get these error messages:

--- quote ---
Checkbox viewhelpers can only be bound to properties of type boolean or 
array. Property "categories" is of type 
"Tx_Extbase_Persistence_ObjectStorage".
--- /quote ---

any idea what could help?

i use TYPO3 4.6.

kind regards.

roland