Hi acrolink et al,
I know I’m a bit late to this party but I was reading this for inspiration on a similar issue today and I ended up just using a fragment like so:
books_query =
from(
b in Mango.Books.Book,
left_join: r in Mango.Records.Record,
on: r.book_id == b.id,
select: %{
:book_id => fragment("distinct on (?) ?", b.id, b.id),
:record_id => r.id,
:due_for_return => r.due_for_return,
:returned_at => r.returned_at
},
order_by: [asc: b.id, desc: r.due_for_return]
)
My particular case didn’t allow for the methods outlined above so I gave that a go and it worked.
Also, I’ve sorted by due_for_return instead of id just in case something crazy happened and your record.id’s ended up out of sync with due_for_return.
I’d be interested to see how this pans out for you.
S.