Returning Array in USER_INT userFunc leads to <!--INT_SCRIPT output - typo3

Question

I have a userFunc which I call via
lib.random = USER_INT
lib.random {
userFunc = My\Plugin\UserFunc\Functions->random
}
when I return a Array and try to access it is fails.
<v:variable.set name="random" value="{f:cObject(typoscriptObjectPath: 'lib.random')}" />
{random.max}
When I try to debug out it I get some <!--INT_SCRIPT string
Did anyone know the problem and a Solution?
/e:
I would like to make the problem a little clearer by describing the Szenario.
I have a Plugin with a Login form. When the User logs in I set a JWT with various basic informations (name, email).
This Informations have to be displayed on various places around the Website, not only on one page (for example profile page). Some cases are prefilled forms or just silly "Hello, Paul" stuff.
So when I first log in (Fresh browser, no cache) then I read "Hello, Paul" after I log out and log in with a another Account (Lets call it "Peter") then It still is written "Hello, Paul" , nor "Hello, Peter". When I clear my browser Cache then everything is fine.
Maybe this helps maybe to solve my dilemma. :)

Answer 1

TL;DR: uncached parts in TYPO3 are replaced in the generated page output string using markers and cannot communicate in the direction intended here. Selectively caching, disabling cache or detaching the data from the main request (with XHR or other) are the only possible methods.
It should be clear that USER_INT achieves its functionality by string replacement in the generated page body. This means, among other things, that:
You can never pass the output of a USER_INT to anything in Fluid, not even if the entire page is uncached. You will effectively be passing a string containing <!---INT_SCRIPT... (the entire marker).
You can however generate USER_INT from Fluid, which ends up in the generated page, which is then replaced with the rendered object (use f:cObject to render a USER_INT or COA_INT).
Then there are the use case context considerations. First of all, a cookie (in practice) changes the request parameters and should be part of the cache identifier that your page uses (it is not this way by default). Second, if said cookie changes the way the page renders (and it does, given your use case) this will cause trouble when the page is cached. Third, the page output changing based on a cookie indicates perhaps sensitive information or at the very least user-specific information.
Taking the above into account your use case should do one of the following things:
Either render the entire chunk of output that changes based on cookie, as USER_INT. That means wrapping the entire Fluid output and rendering it all without caching. Note that template compiling still happens (and you can use f:cache.static to hard-cache certain parts if they never change based on request parameters).
Or add the cookie value to the cHash (page hash value) so that having the cookie set means you request a specific cached version that matches the cookie. This is the preferred way if your cookie's values is generally the same for many users (e.g. it contains a selected contact person from a limited list and stores that in a cookie).
Or, in the case that your output contains actually sensitive information, require that the content element or page is only available when logged in with a specific group. This has two purposes: first, it protects the page from being viewed without authentication - but second, it also makes the page content not cache or be cached with the frontend user group ID as part of the cache identity.
Refactor to XHR request and make whichever endpoint it uses, a USER_INT or manually disabled cache context, then load the data. Or set the actual data in the cookie, then use JS to insert the values where needed.
Hopefully that clarifies the different contexts and why they can't communicate in the direction you're attempting; even if they had been exchanging strings instead of arrays.
See also: .cache sub-object in TypoScript which is where you would be able to craft a unique cache identifier for use case 2 described above.

Answer 2

USER_INT are not Cached, so the values for this are replaced after the cache is build up.
I think f:cObject is the wrong way. Implement an own ViewHelper to get the same data should be an better way.
<?php
namespace My\Plugin\ViewHelpers;
use TYPO3Fluid\Fluid\Core\Rendering\RenderingContextInterface;
use TYPO3Fluid\Fluid\Core\ViewHelper\AbstractViewHelper;
use TYPO3Fluid\Fluid\Core\ViewHelper\Traits\CompileWithRenderStatic;
class RandomViewHelper extends AbstractViewHelper
{
use CompileWithRenderStatic;
/**
* #var boolean
*/
protected $escapeOutput = false;
/**
* #param array $arguments
* #param \Closure $renderChildrenClosure
* #param RenderingContextInterface $renderingContext
* #return string
*/
public static function renderStatic(
array $arguments,
\Closure $renderChildrenClosure,
RenderingContextInterface $renderingContext
) {
return rand();
}
}
Now you can use it like following:
{my:random()} or <my:random />