- multi =
- Enum.reduce(users, Multi.new(), fn user, multi ->
- new_tags = mutate_tags(user, tags, action)
- Multi.update(multi, {:user, user.id}, change(user, %{tags: new_tags}))
- end)
+ def untag(%User{} = user, tags),
+ do: update_tags(user, (user.tags || []) -- normalize_tags(tags))