[TYPO3-mvc] set fluid template in controller

[Domi]

Hi,

I'm a bit out of shape in extbase / fluid, haven't had any time 
programming with it. At the moment I want to set the fluid template file.

Through the settings I need to switch between different fluid template 
files (different actions can be choosen through flexform). At the moment 
I pass the value as a variable and from there I render a specific partial.

Is there a more elegant way to do this? Is there an option which sets 
the template file?

Thanks,

Dominic