[TYPO3-extbase] Query Language: Filter on child objects

[DirkHo]

Hi all,

I'm just writing my first extension and have a question where I found no 
google answer for. Hopefully you can and are willing to help me:

I create a sports bet extension (nothing commercial, in german it's 
"Tippspiel"). My Model looks as follows: Several leagues can be created, 
each league has at least one competition, each competition has at least 
one match day, each match day contains one match and every match may 
have several bets. Each bet belongs to one customer.

Currently I iterate over every league, every competition, every 
matchday, every match and every bet in fluid and output it.

What I now want to do is to filter the bets to show only those bets 
belonging to the current frontend user. Is it possible to filter the 
objects to only show those that belong to that user? So that I still can 
iterate starting with the leagues but only matches are shown that have 
bets from that user and as child objects only the bets of that user?

Thanks and kind regards,

Dirk