How to get value from FlexForm to Controller - typo3

Question

I'm practicing on a very easy Extbase Extension and used a FlexForm to get three formula fields.
One of them is called "code" which should go to the EmbedderController.php and then to the viewer List.html.
I checked all tutorials I could find.
I don't understand how to get the FlexForm-value "code" into my Controller.
I get an empty page or don't get any value.
This is my FlexForm: Embedder.xml
<T3DataStructure>
<meta type="array">
<langChildren>0</langChildren>
<langDisable>1</langDisable>
</meta>
<ROOT>
<type>array</type>
<el>
<settings.code>
<TCEforms>
<label>Video Code</label>
<config>
<type>input</type>
<size>20</size>
<max>30</max>
<eval>trim</eval>
</config>
</TCEforms>
</settings.code>
<settings.width>
<TCEforms>
<exclude>1</exclude>
<label>Breite in Pixel</label>
<config>
<type>input</type>
<size>10</size>
<max>10</max>
<eval>trim</eval>
</config>
</TCEforms>
</settings.width>
<settings.height>
<TCEforms>
<exclude>1</exclude>
<label>Höhe in Pixel</label>
<config>
<type>input</type>
<size>10</size>
<max>10</max>
<eval>trim</eval>
</config>
</TCEforms>
</settings.height>
</el>
</ROOT>
</T3DataStructure>
And this is my EmbedderController.php
<?php
namespace HhuMediathek\Hhumediathek\Controller;
/**
* EmbedderController
*/
class EmbedderController extends \TYPO3\CMS\Extbase\Mvc\Controller\ActionController {
/**
* embedderRepository
*
* #var \HhuMediathek\Hhumediathek\Domain\Repository\EmbedderRepository
* #inject
*/
protected $embedderRepository = NULL;
/**
* action list
*
* #return void
*/
public function listAction() {
$this->settings['code'];
}
}
And this is the viewer List.html
<f:layout name="Default" />
<f:section name="main">
<iframe width='570' height='321' style='width: 570px; height: 321px; border: 1px solid #ccc;' src='//xxx.de/embed/{code}' frameborder='0' allowfullscreen></iframe>
</f:section>

Answer 1

Okay I could figure it out myself. For people who struggle with the same problem as I did:
My mistake was, that I didn't need the line $this->settings['code']; in the Controller at all but write {settings.code} in the viewer List.html instead of just {code}. It's completly different than I read it in my book and some tutorials but this actually worked.

Answer 2

The assignment of the view parameter is missing. Therefore change
public function listAction() {
$this->settings['code'];
}
to
public function listAction() {
$this->view->assign('code', $this->settings['code']);
}
This way {code} should be available in the view.

Answer 3

I want not to be restricted to settings.*. I use the following script in my controller.
/** #var ContentObjectRenderer $content */
$content = $this->configurationManager->getContentObject();
$flexFormString = $content->data['pi_flexform'];
$flexFormRaw = GeneralUtility::xml2array($flexFormString);
if (is_callable([FlexformUtilities::class,'arrayFlatten'])) {
$flexFormSimple = FlexformUtilities::arrayFlatten( $flexFormRaw); // second Param is ['data','sDEF','lDEF','vDEF']
$referenceUidsList = $flexFormSimple['referenceList'];
} else {
$referenceUidsList = (int)$flexFormRaw['data']['sDEF']['lDEF']['referenceList']['vDEF'];
}
The Utilities-Class contains the following flattenArray-method
protected const DEFAULT_FLATTEN_KEYS = ['data','sDEF','lDEF','vDEF'];
/**
* https://stackoverflow.com/questions/1319903/how-to-flatten-a-multidimensional-array
*
* #param array $listFlatKeys
* #param $array
* #return array
*/
public static function arrayFlatten( $array, &$listFlatKeys = self::DEFAULT_FLATTEN_KEYS)
{
if (!is_array($array)) {
return $array;
}
if (count($array) === 1) {
$key = array_key_first($array);
$value = self::arrayFlatten( $array[$key],$listFlatKeys);
if (in_array($key, $listFlatKeys)) {
return $value;
} else {
return [$key => $value];
}
}
$return = [];
foreach ($array as $key => $value) {
if (in_array($key, $listFlatKeys)) {
$return[] = self::arrayFlatten( $value, $listFlatKeys);
} else {
$return[$key] = self::arrayFlatten( $value, $listFlatKeys);
}
}
return $return;
}
I use it although in a Alias-similiar viewhelper, to get information of a flex-field in the frontend.