[TYPO3-mvc] Extbase query with AND over 1:n related objects

[g4-lisz at tonarchiv.ch]

Hi there.

Is there a way to do a query like this:

Object from class A (e.g. "book") has a property which is related 1:n to 
class B (e.g. "category"). One book can belong to more than one categories.
Now i like to do a query which finds all books with category B=1 AND B=2 
i.e. the book has to belong to both categories.

If i do something like this:

                 if (count($demand->getCategories()) > 0) {
                         foreach ($demand->getCategories() as $category)
                                 $constraints[] = 
$query->equals('book.category.uid', $category);
                 }
               $query->matching($query->logicalAnd($constraints));

then i get all books which belong to one of the categories (same like " 
$constraints[] = $query->in('book.category.uid', 
$demand->getCategories());")

Any help would be much appreciated!

Cheers,
Till