I'd like to set the frontendUserGroup parameter in the AllowViewHelper but I don't know how to do that.
Sometimes (non-deterministic even if I flush the caches) there pop up this error:
The argument "frontendUserGroup" was registered with type "TYPO3\CMS\Extbase\Domain\Model\FrontendUserGroup", but is of type "string" in view helper "FluidTYPO3\Vhs\ViewHelpers\Security\AllowViewHelper"
Is it right to pass simply the reference of the usergroup as argument as follows?:
{namespace v=FluidTYPO3\Vhs\ViewHelpers}
...
<v:security.allow frontendUserGroup="3">
<f:then>
<span>Access granted</span>
</f:then>
<f:else>
<span>Access denied</span>
</f:else>
</v:security.allow>
The parameter is registered by the ViewHelper as follows:
$this->registerArgument('frontendUserGroup', 'TYPO3\CMS\Extbase\Domain\Model\FrontendUserGroup', 'The FrontendUserGroup to allow/deny');
Based on your example you might just use the security.hasRole ViewHelper shipped with CMS Fluid:
<f:security.ifHasRole role="3">
<f:then>
<span>Access granted</span>
</f:then>
<f:else>
<span>Access denied</span>
</f:else>
</f:security.ifHasRole>
In contrary to the allow ViewHelper from EXT:vhs, this ViewHelper accepts the UID of a user group as argument. Instead of the UID you can also pass the title of the usergroup, but as far as I know this can be ambiguous.