Django Custom Left Outer Join

Question

I have query the Django model with this

news = News.objects.filter(Q(likes__user__isnull=True)|Q(likes__user=user))
.extra(select={\"is_liked\":NewsLikes._m         


        

Answer 1

It's hard to generate this form of LEFT OUTER JOIN without using raw(); Also you need to distinct() duplicated rows. I would use EXISTS which is cleaner and likely to be faster:

news = News.objects.extra(select={'is_liked':
    'EXISTS (SELECT 1 FROM {tbl_2} '
    'WHERE {tbl_2}.news_id = {tbl}.id AND {tbl_2}.user_id = %s)'.format(
        tbl=News._meta.db_table,
        tbl_2=NewsLikes._meta.dbtable)}, select_params=(user.id,))