Only show single item by flexform in Extbase - typo3

Question

I created a small extension that can show a puzzle game. The switchable controller actions I made include list/show (works fine), admin (also fine) and show only.
For show only I want to select a database entry from the flexform which will then be shown by the single view. For that I added a new field to the flexform:
<settings.singlePuzzle>
<TCEforms>
<label>Puzzle to show</label>
<config>
<type>select</type>
<foreign_table>tx_wspuzzle_domain_model_puzzle</foreign_table>
<items>
<numIndex index="0" type="array">
<numIndex index="0">-- Choose --</numIndex>
<numIndex index="1"></numIndex>
</numIndex>
</items>
<size>1</size>
<maxitems>1</maxitems>
<minitems>0</minitems>
</config>
</TCEforms>
</settings.singlePuzzle>
So far so good, if I select an item here and debug it in the list view it seems to select the correct id.
Now I changed the showAction in the controller to look like this:
/**
* action show
*
* #param \Websafari\Wspuzzle\Domain\Model\Puzzle $puzzle
* #return void
*/
public function showAction(\Websafari\Wspuzzle\Domain\Model\Puzzle $puzzle = NULL) {
if(is_null($puzzle)) $puzzle = $this->puzzleRepository->findByUid($this->settings['singlePuzzle']);
$this->view->assign('puzzle', $puzzle);
}
So now I change the action to "show only", select an entry for "singlePuzzle" and then (I think) I should be good to go, but all I get ist the following error:
Required argument "puzzle" is not set.
Obviously I made a mistake, but I don't get it.
First: Why is "puzzle" still required? That's why I added "= NULL" to the function (I also tried adding #ignorevalidation $puzzle to the comment).
Second: Why is it not set? When I debug "$this->settings['singlePuzzle'];" I get an id for a puzzle object.
Would be great if someone could point out my error, because I'm really stuck here. Thnx a lot!

Answer 1

The problem is that the reflection information of a class (arguments etc.) are cached in Extbase. So if you change the definition and don't clear the respective cache, it still will require your argument.
You need to clear the "System caches" in TYPO3. There are three ways to do it:
If you are in development context, you will have the button (with the red flash icon) in the backend.
You can enable the button through User TSconfig in production context using options.clearCache.system = 1.
A button for clearing the system cache is in the install tool, section "Important actions".
You can also manually clear all cache related tables in PhpMyAdmin
TRUNCATE table cf_cache_hash;
TRUNCATE table cf_cache_hash_tags;
TRUNCATE table cf_cache_pages;
TRUNCATE table cf_cache_pagesection;
TRUNCATE table cf_cache_pagesection_tags;
TRUNCATE table cf_cache_pages_tags;
TRUNCATE table cf_cache_rootline;
TRUNCATE table cf_cache_rootline_tags;
TRUNCATE table cf_extbase_object;
TRUNCATE table cf_extbase_object_tags;
TRUNCATE table cf_extbase_reflection;
TRUNCATE table cf_extbase_reflection_tags;
TRUNCATE cf_extbase_typo3dbbackend_queries;
TRUNCATE cf_extbase_typo3dbbackend_queries_tags;
TRUNCATE cf_extbase_typo3dbbackend_tablecolumns;
TRUNCATE cf_extbase_typo3dbbackend_tablecolumns_tags;
TRUNCATE cf_extbase_datamapfactory_datamap;
TRUNCATE cf_extbase_datamapfactory_datamap_tags;
This also truncates query cache etc. what can be useful in some situation.
As soon as the cache is cleared, it should work.
BTW, just to be on the safe side, you should typecast the UID from FlexForm:
if(is_null($puzzle)) $puzzle = $this->puzzleRepository->findByUid((int)$this->settings['singlePuzzle']);