Load nested association and select count at the same time

Questions & Help Questions
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4

I did something similar sometime ago.
I used a virtual field for the count then make a querry like:

....,
select_merge: %{factions_count: count(factions.id)
....

So your query could look like:

query =
  from instance in Instance,
    left_join: factions in assoc(instance, :factions),
    left_join: profils in assoc(factions, :profils),
    preload: [factions: {factions, profils: profils}],
    order_by: [desc: instance.id],
    select_merge: %{registered_profils: count(profils.id)

But to be honest I don’t know if this is the best way but it works. ^^