[FLOW3-general] Fluid - How to add checkbox of type boolean

[Mick]

Hi all,

i have a question about adding checkbox to a fluid form.

The checkbox looks like:

<f:form action="update" object="{task}" name="task" 
enctype="multipart/form-data">
     <f:form.checkbox name="completed" property="completed" value="true" 
checked="checked"/>
	<f:form.submit value="Submit task list"/>
</f:form>

The model look like:
see attachement: Task.php


After submitting the form i got the following Exception:
Uncaught Exception in FLOW3
#1244465559: Expected property of type boolean, but got string for 
F3\GTasks\Domain\Model\Task::completed (More information)

F3\FLOW3\Persistence\Exception\UnexpectedTypeException thrown in file
Packages/Framework/FLOW3/Classes/Persistence/Backend/AbstractBackend.php 
in line 541.


How should i setup the form correctly to get the boolean value into the 
model?

Cheers,
Mick