ruby - 将嵌套哈希数组缩减为扁平的键/值对数组

Question

给定以下数据结构:

[
    [:created_at, "07/28/2017"],
    [:valid_record, "true"],
    [:cs_details, { gender: 'm', race: 'w', language: nil } ],
    [:co_details, { description: 'possess', extra: { a: 'a', b: 'b', c: 'c'} } ]
]

我想要一组键/值对数组:

[
        [:created_at, "07/28/2017"],
        [:valid_record, "true"],
        [:gender, 'm'],
        [:race, 'w'],
        [:description, "process"]
        [:a, "a"],
        [:b, "b"],
        [:c, "c"]
]

问题是我不知道如何展平这些散列。 flatten 不做任何事情:

arr.map(&:flatten)
 => [[:created_at, "07/28/2017"], [:valid_record, "true"], [:cs_details, {:gender=>"m", :race=>"w", :language=>nil}], [:co_details, {:description=>"possess", :extra=>{:a=>"a", :b=>"b", :c=>"c"}}]] 

所以我知道 flat_map 也无济于事。我什至无法使用 to_a 将这些哈希值转换为数组:

arr.map(&:to_a)
 => [[:created_at, "07/28/2017"], [:valid_record, "true"], [:cs_details, {:gender=>"m", :race=>"w", :language=>nil}], [:co_details, {:description=>"possess", :extra=>{:a=>"a", :b=>"b", :c=>"c"}}]] 

上述方法的问题在于它们仅适用于顶级索引。这些散列嵌套在数组中。所以我尝试减少，然后在结果上调用 flat_map:

arr.reduce([]) do |acc, (k,v)|
  if v.is_a?(Hash)
    acc << v.map(&:to_a)
  else
    acc << [k,v]
  end
  acc
end.flat_map(&:to_a)
=> [:created_at, "07/28/2017", :valid_record, "true", [:gender, "m"], [:race, "w"], [:language, nil], [:description, "possess"], [:extra, {:a=>"a", :b=>"b", :c=>"c"}]] 

不完全在那里，但更近了。有什么建议吗？

Answer 1

▶ flattener = ->(k, v) do
▷   case v
▷   when Enumerable then v.flat_map(&flattener)  
▷   when NilClass then []  
▷   else [k, v]  
▷   end  
▷ end  
#⇒ #<Proc:0x000000032169e0@(pry):26 (lambda)>
▶ input.flat_map(&flattener).each_slice(2).to_a
#⇒ [
#    [:created_at, "07/28/2017"],
#    [:valid_record, "true"],
#    [:gender, "m"],
#    [:race, "w"],
#    [:description, "possess"],
#    [:a, "a"],
#    [:b, "b"],
#    [:c, "c"]
#  ]