使用 Ruby/Rails 将嵌套散列展平为单个散列 [英] Flattening nested hash to a single hash with Ruby/Rails

问题描述

我想展平"(不是经典意义上的 .flatten)具有不同深度级别的散列，如下所示:

I want to "flatten" (not in the classical sense of .flatten) down a hash with varying levels of depth, like this:

{
  :foo => "bar",
  :hello => {
    :world => "Hello World",
    :bro => "What's up dude?",
  },
  :a => {
    :b => {
      :c => "d"
    }
  }
}

向下变成一层散列，所有嵌套的键合并成一个字符串，所以它会变成这样:

down into a hash with one single level, and all the nested keys merged into one string, so it would become this:

{
  :foo => "bar",
  :"hello.world" => "Hello World",
  :"hello.bro" => "What's up dude?",
  :"a.b.c" => "d"
}

但是我想不出一个好的方法来做到这一点.这有点像 Rails 添加到 Hashes 的 deep_ 辅助函数，但并不完全相同.我知道递归是这里的最佳选择，但我从未在 Ruby 中编写过递归函数.

but I can't think of a good way to do it. It's a bit like the deep_ helper functions that Rails adds to Hashes, but not quite the same. I know recursion would be the way to go here, but I've never written a recursive function in Ruby.

推荐答案

你可以这样做:

def flatten_hash(hash)
  hash.each_with_object({}) do |(k, v), h|
    if v.is_a? Hash
      flatten_hash(v).map do |h_k, h_v|
        h["#{k}.#{h_k}".to_sym] = h_v
      end
    else 
      h[k] = v
    end
   end
end

flatten_hash(:foo => "bar",
  :hello => {
    :world => "Hello World",
    :bro => "What's up dude?",
  },
  :a => {
    :b => {
      :c => "d"
    }
  })
# => {:foo=>"bar", 
# =>  :"hello.world"=>"Hello World", 
# =>  :"hello.bro"=>"What's up dude?", 
# =>  :"a.b.c"=>"d"} 

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