Ruby中如何生成带ActiveSupport::HashWithIndifferentAccess标识的YAML

问题原因 #

JSON.parse默认返回的是普通Ruby Hash类型，直接调用to_yaml生成的内容自然不会携带ActiveSupport::HashWithIndifferentAccess的类型标识。你需要将JSON解析结果的所有嵌套层级的Hash都统一转为HashWithIndifferentAccess类型，再生成YAML即可得到预期格式。

解决方案 #

首先安装activesupport依赖（如果是Rails环境可跳过这一步）：

gem install activesupport

调整后的代码如下：

require 'yaml'
require 'json'
# 引入HashWithIndifferentAccess依赖
require 'active_support/core_ext/hash/indifferent_access'

# 递归将所有嵌套Hash转为HashWithIndifferentAccess
def recursive_turn_to_hwia(obj)
  case obj
  when Hash
    obj.each_with_object(HashWithIndifferentAccess.new) do |(key, value), result|
      result[key] = recursive_turn_to_hwia(value)
    end
  when Array
    obj.map { |item| recursive_turn_to_hwia(item) }
  else
    obj
  end
end

origin_json_str = '{"accepted":{"first_order_date":{"consition":"between_date","value":"2021-11-28 00:00:00&2021-11-22 00:00:00"}},"removed":{}}'

parsed_hash = JSON.parse(origin_json_str)
hwia_hash = recursive_turn_to_hwia(parsed_hash)

puts hwia_hash.to_yaml

输出效果 #

运行上述代码得到的YAML输出如下：

--- !ruby/hash:ActiveSupport::HashWithIndifferentAccess
accepted: !ruby/hash:ActiveSupport::HashWithIndifferentAccess
  first_order_date: !ruby/hash:ActiveSupport::HashWithIndifferentAccess
    consition: between_date
    value: 2021-11-28 00:00:00&2021-11-22 00:00:00
removed: !ruby/hash:ActiveSupport::HashWithIndifferentAccess {}

注：你给出的预期示例中key为number_of_order属于示例笔误，实际输出会保留原JSON的first_order_date字段，类型标识完全符合你的预期。

内容的提问来源于stack exchange，提问作者HG Webs