[TYPO3-mvc] Simple query by uid question

[Felix Eggbert]

Hi all,

I've just started working with extbase and fluid and I am kind of at the
very beginning.thanks to Sebastians and Jochens book ("Zukunftssichere
Extensions...") I am slowly getting into things...I have very good
experience with installing and setting up TYPO3 and some experience in PHP
and MySQL programming but I am beginner in typo3 extension
programming...therefore I hope this is the right place to ask this kind of
noob question...

This is my problem:

I have a model named "Category". This category has a 0..1 relation
("parent") to itself which is supposed to allow setting a parent category
which is from the same model.

The main categories have a (hidden) parent category ("main", uid=2) whose
only purpose is holding all main categories at the top level. Now I want to
output all top-level categories, meaning all categories with parent uid=2.

My controller action looks like this:

	/**
	 * List all available main categories
	 * 
	 * @return string The rendered view
	 */
	public function listAllMainAction(){
		$mainCategories =
$this->categoryRepository->findMainCategories();
		$this->view->assign('categories', $mainCategories);
	}

And my repository method looks like this

	/**
	 * Finds all main categories
	 *
	 * @return array Matched categories
	 */
	public function findMainCategories() {
		$motherCategory = 2;
		$query = $this->createQuery();
	
$query->matching($query->contains('parent',$this->findByUid((int)$motherCate
gory)));
		return $query->execute;
	}

But I don't get any results! A var_dump in listAllMainAction for
$mainCategories returns null. Of course I have set up all required
categories and a "normal" $this->categoryRepository->findAll() does return a
list of all categories.

What am I doing wrong?

Thanks for your help!

Regards, 
Felix Eggbert