gistfile1.rb

  def self.tree(path = nil)
    Rails.cache.fetch("folder-tree-#{path}", expires_in: 0) do 
      folders = Folder.where('path LIKE ?', "#{path}%").all
      path_parts = path.to_s.count('/')
      local_root = root
      local_first_tier = []

      folders.each do |folder|
        folder.children = folders.select { |f| f.parent_id == folder.id }.sort { |a, b| a.position <=> b.position }
        local_root = folder if path == folder.path
        local_first_tier << folder if folder.path.count('/') == path_parts
      end

      local_root.children = local_first_tier if local_root.root?
      local_root
    end
  end