我喜欢这一行，当我不使用Rails时，因为这样我就不必在处理它时进行第二个哈希并持有两组数据:

my_hash = { "a" => 1, "b" => "string", "c" => true }

my_hash.keys.each { |key| my_hash[key.to_sym] = my_hash.delete(key) }

my_hash
=> {:a=>1, :b=>"string", :c=>true}

哈希#delete返回已删除键的值

ruby-1.9.2-p180 :001 > h = {'aaa' => 1, 'bbb' => 2}
 => {"aaa"=>1, "bbb"=>2} 
ruby-1.9.2-p180 :002 > Hash[h.map{|a| [a.first.to_sym, a.last]}]
 => {:aaa=>1, :bbb=>2}

类似于前面的解决方案，但写得有点不同。

This allows for a hash that is nested and/or has arrays. Get conversion of keys to a string as a bonus. Code does not mutate the hash been passed in. module HashUtils def symbolize_keys(hash) transformer_function = ->(key) { key.to_sym } transform_keys(hash, transformer_function) end def stringify_keys(hash) transformer_function = ->(key) { key.to_s } transform_keys(hash, transformer_function) end def transform_keys(obj, transformer_function) case obj when Array obj.map{|value| transform_keys(value, transformer_function)} when Hash obj.each_with_object({}) do |(key, value), hash| hash[transformer_function.call(key)] = transform_keys(value, transformer_function) end else obj end end end

更短的一行代码:

my_hash.inject({}){|h,(k,v)| h.merge({ k.to_sym => v}) }

会像下面这样工作吗?

new_hash = Hash.new
my_hash.each { |k, v| new_hash[k.to_sym] = v }

它会复制哈希值，但大多数时候你不会在意。可能有一种不复制所有数据的方法。

你可以偷懒，把它用lambda括起来:

my_hash = YAML.load_file('yml')
my_lamb = lambda { |key| my_hash[key.to_s] }

my_lamb[:a] == my_hash['a'] #=> true

但这只适用于从散列中读取数据，而不是写入数据。

要做到这一点，你可以使用hash# merge

my_hash = Hash.new { |h,k| h[k] = h[k.to_s] }.merge(YAML.load_file('yml'))

init块将按需一次转换键，但如果您在访问符号版本后更新键的字符串版本的值，则符号版本将不会更新。

irb> x = { 'a' => 1, 'b' => 2 }
#=> {"a"=>1, "b"=>2}
irb> y = Hash.new { |h,k| h[k] = h[k.to_s] }.merge(x)
#=> {"a"=>1, "b"=>2}
irb> y[:a]  # the key :a doesn't exist for y, so the init block is called
#=> 1
irb> y
#=> {"a"=>1, :a=>1, "b"=>2}
irb> y[:a]  # the key :a now exists for y, so the init block is isn't called
#=> 1
irb> y['a'] = 3
#=> 3
irb> y
#=> {"a"=>3, :a=>1, "b"=>2}

你也可以让init块不更新哈希，这将保护你免受这种错误，但你仍然容易受到相反的攻击-更新符号版本不会更新字符串版本:

irb> q = { 'c' => 4, 'd' => 5 }
#=> {"c"=>4, "d"=>5}
irb> r = Hash.new { |h,k| h[k.to_s] }.merge(q)
#=> {"c"=>4, "d"=>5}
irb> r[:c] # init block is called
#=> 4
irb> r
#=> {"c"=>4, "d"=>5}
irb> r[:c] # init block is called again, since this key still isn't in r
#=> 4
irb> r[:c] = 7
#=> 7
irb> r
#=> {:c=>7, "c"=>4, "d"=>5}

所以要注意的是在两种键形式之间切换。坚持用一个。