ruby - 如何永久更新 Ruby 中的哈希值？

Question

所以我在这里看到了关于如何写入外部文本文件等的问题。例如，将我的哈希值写入我放置的另一个文件:

hash = {
  Key1: Value1,
  Key2: Value2
}
open(FileToWriteTo, 'w') do |f|
  hash.each { |key, value| f.puts "#{key}: #{value}" }

但我想要实现的是，如果我运行该程序并将某些内容添加到我的哈希列表中，那么下次我运行并显示该哈希时，新添加的内容就会出现。这是我用来添加到哈希中的代码:

puts "Type 'add' to add an item to the hash"

choice = gets.chomp.downcase

case choice
when 'add'
  puts "What do you want to add?"
  addition = gets.chomp
  if hash[addition.to_sym].nil?
    puts "What value will #{addition} have? (integer)"
    add_value = gets.chomp
    hash[addition.to_sym] = add_value.to_i
      puts "#{addition} has been added with a value of #{value}."
  else
    puts "That item already exists! Its value is #{hash[addition.to_sym]}."
end

所以如果我添加项目，重新运行程序并选择显示而不是添加，我应该如何让最后添加的显示。谢谢。

Answer 1

这是您可以使用的代码。它利用 yaml 来存储哈希。

require 'yaml'

file = '/tmp/test.yml'
if File.exists?(file)
  hash = YAML::load_file(file)  # load yaml
else
  hash = Hash.new
end

puts "Type 'add' to add an item to the hash"
choice = gets.chomp.downcase

if choice == 'add'
  puts "What do you want to add?"
  addition = gets.chomp
  if hash[addition.to_sym].nil?
    puts "What value will #{addition} have? (integer)"
    add_value = gets.chomp
    hash[addition.to_sym] = add_value.to_i
    puts "#{addition} has been added with a value of #{add_value}."
  else
    puts "That item already exists! Its value is #    {hash[addition.to_sym]}."
  end
end

File.open(file, 'w') {|f| f.write hash.to_yaml } #store yaml