I've got a method that sorts a collection by an array of ids like so:
def selected_components
ids = @document.publications.rank(:position).map(&:component_id)
Component.find(ids).sort_by { |c| ids.index(c.id) }
end
This works fine, but I want to sort the result by the order of ids as efficiently as possible. Apparently my method is not the most efficient, although I'm not 100% why that is.
Why isn't this so efficient? Any advice? Thanks so much.
I'm pretty sure: if you search for efficiently, you must let the db do the work.
First, eager load publications with its components:
@document = Document.includes(publications: :component).find_by(...)
Then rank and map the components:
def selected_components
@document.publications.rank(:position).map(&:component)
end
Now, selected_components don't need to do db access. Also, you don't need to sort data two times, only one (in rank).
Edited: Eager load, its recomended as a best practice to fix the n + 1 issue here.
