Django how select one photo per gallery in one call to DB?

[piasek piasek]

I have two models: 

Gallery and Photo, Photo has Gallery as FK.

Is it possible to return in one call one photo per gallery?

I already tried:

photos = Photo.objects.filter(active=True)

photos.annotate(g=Count('gallery'))

unfortunately when I call query I got something like that:

GROUP BY "wall_photo"."id", "wall_photo"."added_date", "wall_photo"."title", "wall_photo"."active", "wall_photo"."gallery_id", "wall_photo"."description"

which return me the same as above photos query without annotate :(

I tried also transform photos to SQL query and add group_by

query_photo = photos.query

query_photo.group_by = ['gallery']

Photo.objects.raw(query_photo.__str__())

and again I got the same result.

Do you know a way to do it in one call?