[TYPO3-templavoila] Using TV for Extensions without the use of multiple sheets in the DS

[Nils Meyer]

Hi,

I am currently writing a frontend plugin which should use TemplaVoila 
for the output, as I don't like using plain HTML in my scripts at all. 
However, every (there are like 2, mininews and tv_loginbox) example I 
see uses sheets in the Datastructure. I don't need that but I am unable 
to get it to work without sheets, it always puts out nothing or the 
original template HTML Code.

Let's say you use the following DS:
<T3DataStructure>
    <ROOT>
        <tx_templavoila>
            <title>Produktansicht</title>
            <description>Root Element für die Produktansicht</description>
            <tags>div:inner</tags>
        </tx_templavoila>
        <type>array</type>
        <el>
            <field_name>
                <tx_templavoila>
                    <title>Produktname</title>
                    <description>Name des Produkts</description>
                    <tags>*:inner</tags>
                </tx_templavoila>
            </field_name>

What do I do to set field_name to the value  I have? In examples with 
sheet names it works like that:

<T3DataStructure><sheets><sArchive><ROOT><el>

becomes
$this->TA['sub']['sArchive']['sub']['field_archiveListing']['sub']['element_even']
                                                ^^^ <ROOT> should start 
here.

So I suppose for my example:
<T3DataStructure><ROOT><el><field_name>
would become:
$this->TA['sub']['field_name']

However, using
$out = $this->TMPLobj->mergeDataArrayToTemplateArray($this->TA['sub'], 
array('field_name' => 'Test!'));

returns an empty String. What am I doing wrong and where could I read to 
get more information?

regards
Nils