mongo_logger.rb

# Original
  def add_metadata(options={})
    options.each_pair do |key, value|
      unless [:messages, :request_time, :ip, :runtime].include?(key.to_sym)
        next if value.is_a?(Hash)
        options.delete(key)
        info("[MongoLogger : metadata] '#{key}' => '#{value}'")
        @mongo_record[key] = value
      else
        raise ArgumentError, ":#{key} is a reserved key for the mongo logger. Please choose a different key"
      end
    end
  end

# Refactor and add nested values
  def add_metadata(options={})
    if options.present?
      raise ArgumentError, "#{RESERVED_MONGO_LOGGER_KEYS.join(', ')} are reserved keys for the mongo logger. Please choose a different key" if options.any?{|key, value| RESERVED_MONGO_LOGGER_KEYS.include?(key.to_sym)}
     
      @mongo_record.recursive_merge!(options)
    end
  end

class Hash
  def recursive_merge!(other)
    other.each do |key, value|
      myval = self[key]
      if value.is_a?(Hash) && myval.is_a?(Hash)
        myval.recursive_merge!(value)
      else
        self[key] = value
      end
    end
    self
  end
end