Rails: correct way of turning activerecord relation to array?

If you need to access to the query result, just use #to_a on ActiveRecord::Relation instance.

At rails guides you can find on notable changes at Rails 4.0: “Model.all now returns an ActiveRecord::Relation, rather than an array of records. Use Relation#to_a if you really want an array. In some specific cases, this may cause breakage when upgrading.” That is valid for other relation methods like :where.

selected_videos = videos.to_a.uniq{|p| p.author}