有沒有更有效的方法來從Ruby對象的集合構建排序的哈希？

Question

我正在構建一個排序的哈希，以供在Rails應用程序中的分組選擇中使用。 我沒有使用ActiveRecord。 有沒有比這更有效或更清潔的方法？

def for_select
  select_list = {}
  Department.all.each do |dept|
    select_list[dept.top_level_department_cn] ||= []
    select_list[dept.top_level_department_cn] << [dept.cn, dept.sorid]
  end
  select_list.each_value { |select_options| select_options.sort_by!(&:first) }
             .sort
             .to_h
end

Answer 1

def for_select
  Department.all
  .sort
  .group_by(&:top_level_department_cn)
  .each_value{|v| v.map!{|dept| [dept.cn, dept.sorid]}.sort_by!(&:first)}
end

Answer 2

另一個解決方案：

def for_select
  # @see: https://stackoverflow.com/questions/2698460#answer-28916684
  select_list = Hash.new { |h, k| h[k] = [] }

  Department.all
    .map { |d| [d.top_level_department_cn, [d.cn, d.sorid]] }
    .sort
    .each { |top_level_cn, data| select_list[top_level_cn] << data }

  select_list
end