ruby-on-rails - rails中未定义的方法`@'

Question

有人知道为什么

hash['City'] = {}
hash['City']['answer0'] = 'foo'

得到以下错误：

undefined method `+@' for {"answer0"=>"foo"}:Hash

谢谢

Answer 1

如果您想拥有“多维”哈希，您需要正确定义哈希，如下所示：

a = Hash.new { |hash, key| hash[key] = Hash.new(&hash.default_proc) }

然后你可以这样做：

a['city']['answer0'] = 'foo'