[TYPO3-mvc] My first ext base mvc extension, problems with GET / POST

[Mic Raf]

Hi all,

It's probably a noob question but it's my very first try and haven't find so much documentation on the subject.

I have a list showing my database items.
What I want to do si a search that modify the list view.
So I create a form with post to list action controller.

I modified the list action to receive the datas but when I fill the form with a word and I click on send, I have that error:
#1297759968: Exception while property mapping at property path "":The identity property "the search word typed" is no UID.

Here is my action controller:

	public function listAction(\TYPO3\Myfirstext\Domain\Model\MyFirstExt $searchString) {
		$users = $this->userRepository->findAll();
		$this->view->assign('users', $user);
		$this->view->assign('searchString', $searchString);
}


Thanks for your help!
Mic