[TYPO3-mvc] Howto check if an object exists in a objectstorage

[Alex Bailey]

Hi :)
I have a problem with a query method, I think it's pretty simple but 
I've never done it. Simple question: how can I check (in a repository 
query) if a property (which is an objectstorage) contains an object?

I tried to use the $query->contains method but it doesn't seem to work.

Big thanks in advance

Alex