Single format, parent, children, grandchildren relationship, of course, all are one to many association.

i try to use Criteria with setFetchMode(Ass_name,FetchMode.EAGER)to get whole object tree.

For parent, children level is fine. but for grandchild failed.

So try HQL with left join in fetch, failed too.

So any advise is welcomed!

You need to include your mapping and config files, but you might not have set you hibernate.max_fetch_depth in your config appropriately. This is just a guess, it's hard to know without seeing your mapping and config files.

You can only eager fetch one many-association per query/criteria