fetch join

Myk · **Joined:** Sun Jan 04, 2004 2:46 pm **Posts:** 147

Quote:

Note that, in the current implementation, only one collection role may be fetched in a query.

I found this in the doco ( 10.3 ) in the fetch join section. Does this mean I can't fetch multiple collections of the same object type like this?

Code:

from eg.Cat as cat 
    join cat.mate as mate
    left join cat.kittens as kitten

or does it mean I can't have more than one parent object fetching it's collections in a single query like this?

Code:

from eg.Cat as cat, eg.Mouse as mouse
    join cat.mate as cat_mate
    join mouse.mate as mouse_mate

Or something else.

Cheers.

Myk.

michael · **Posted:** Fri Jan 16, 2004 10:25 am

You can join multiple collections, but not fetch join multiple collections.

Myk · **Joined:** Sun Jan 04, 2004 2:46 pm **Posts:** 147

Oops my bad I posted the wrong query code. The first should have been this.

Code:

from eg.Cat as cat 
    inner join fetch cat.mate
    left join fetch cat.kittens

second should be this...

Code:

from eg.Cat as cat, eg.Mouse as mouse 
    inner join fetch cat.mouse_mate
    inner join fetch mouse.mouse_mate

Note the first is in the doco so perhaps it should be amended if hibernate does not do multiple collection fetches on a single object?

Cheers.

Myk.

Myk · **Joined:** Sun Jan 04, 2004 2:46 pm **Posts:** 147

Doh again wrong. The example is fine as it is, one is a single object reference ( mate ) the other is a collection ( kittens ).

emmanuel · **Posted:** Fri Jan 16, 2004 1:37 pm

All of these works, because there is only 1 fetched collection (kittens). mate isn't a collection but a *-to-one