[TYPO3-mvc] HMAC check fails / form view helper

[g4-lisz at tonarchiv.ch]

Hi,

I already wrote to this list concerning this issue, but i got now answer.

This time i try to describe the solution i'm looking for more precisely.

Normally the form view helper can be used in a search form like this 
(e.g. with select input type):

<f:form name="demand" object="{demand}" action="results">
<f:form.select property="city" options="{cities}" optionLabelField="name" />
<f:form.submit value="Search" />
</f:form>

(Class "demand" has a property "city"; A list of all cities is attached 
to the view as "cities".)

I don't like the drop-down (select) input type for my purpose. A list 
(ul) with all city's names as links to click on would be more straight 
forward.

Is there a way to get this working?

I tried it with uri.action view helper in a ForEach loop:
<f:for each="{cities}" as="city"><a 
href="{f:uri.action(action:'result',arguments:{demand:{city:city}})}">{city.name}</a></f:for>

But this alway leads to a HMAC check error. Maybe a could write a view 
helper of my own which sets the HMAC correctly?

Any help would be much appreciated!

Till