How do you update the rails index controller to accept ids parameters when using Ember Data coalescing?

If you are using Rails API and Ember JS and enable coalescing in Ember Data (example), Ember Data will coalesce your queries into one that will automatically hit your index controller with an ids parameter of what it wants.

How do you update the index controller? Is there a ActiveRecord function for retrieving all or some records based on a parameter being included?

def index
  ids = params[:ids]
  if ids.present?
    @advertisers = Advertiser.where(id: ids)
  else
    @advertisers = Advertiser.all
  end

  render json: @advertisers
end