[TYPO3-mvc] Checkboxes for a collection

[Jan Kornblum]

Dear newsgroup,

i've got a fluid form where some records are listed. For each records 
the user can select an 0 or 1 (like "yes" or "no"):

<f:for each="{documents}" as="document">
   <f:form.select options="{0: 0, 1: 1}" 
property="documents.{document.uid}"></f:form.select>
</f:for>

The form is based on an own filter model / class, where its property 
"documents" is declared as an array. Now instead of using an select 
field i would like to use a checkbox for each record.

<f:form.checkbox property="documents.{document.uid}" 
value="1"></f:form.checkbox>

But fluid doesn't like this: "Checkbox viewhelpers can only be bound to 
properties of type boolean or array. Property "documents[2]" is of type 
"NULL"."

So how can i declare a property "documents" in my filter model, which 
should be an array (to hold the ids of the documents as a key) but also 
should be able to be mapped by an fluid checkbox?

Kind regards, Jan