underscoring json in ruby

1.rb

   def self.underscore_hash(hash)
     hash.inject({}) do |underscored, (key, value)|
       value = underscore_hash(value) if value.is_a?(Hash)
       value = value.map { |v| underscore_hash(v) } if value.is_a?(Array)
       underscored[key.underscore] = value
       underscored
     end
   end

2.rb

   def self.underscore_hash(hash)
     hash.inject({}) do |underscored, (key, value)|
       underscored[key.underscore] = case value
         when Hash: underscore_hash(value)
         when Array: value.map {|v| underscore_hash(v)}
         else value
       end
       underscored
     end
   end

3.rb

  def self.underscore_hash(camel_hash)
    camel_hash.inject({}) do |underscored, (key, value)|
      value = case value
                when Hash: underscore_hash(value)
                when Array: value.map {|v| underscore_hash(v)}
                else value
              end
      underscored[key.underscore] = value
      underscored
    end
  end

4.rb

  def self.underscore(json)
    case json
    when Hash
      json.inject({}) do |underscored, (key, value)|
        underscored[key.underscore] = underscore_hash(value)
        underscored
      end
    when Array
      json.map {|v| underscore_hash(v)}
    else
      json
    end
  end