通过键数组设置ruby哈希元素值

这是我得到的：

hash = {:a => {:b => [{:c => old_val}]}} keys = [:a, :b, 0, :c] new_val = 10 

哈希结构和密钥集可以变化。
我需要得到

 hash[:a][:b][0][:c] == new_val 

谢谢！

Answer 1

您可以使用inject来遍历嵌套结构：

 hash = {:a => {:b => [{:c => "foo"}]}} keys = [:a, :b, 0, :c] keys.inject(hash) {|structure, key| structure[key]} # => "foo" 

所以，你只需要修改它就可以对最后一个键进行设置。 也许是这样的

 last_key = keys.pop # => :c nested_hash = keys.inject(hash) {|structure, key| structure[key]} # => {:c => "foo"} nested_hash[last_key] = "bar" hash # => {:a => {:b => [{:c => "bar"}]}} 

Answer 2

与Andy相似，但您可以使用Symbol#to_proc来缩短它。

 hash = {:a => {:b => [{:c => :old_val}]}} keys = [:a, :b, 0, :c] new_val = 10 keys[0...-1].inject(hash, &:fetch)[keys.last] = new_val