如何从嵌套哈希获得密钥或密钥存在的价值？

如何从嵌套哈希中获取密钥的值或密钥的存在？

例如：

a = { "a"=> { "b" => 1, "c" => { "d" => 2, "e" => { "f" => 3 } }}, "g" => 4} 

有没有直接的方法来获得“f”的值？ 或者是否有一种方法可以知道嵌套哈希中是否存在密钥？

Answer 1

 %w[acef].inject(a, &:fetch) # => 3 %w[acex].inject(a, &:fetch) # > Error key not found: "x" %w[x].inject(a, &:fetch) # => Error key not found: "x" 

或者，为了避免错误：

 %w[acef].inject(a, &:fetch) rescue "Key not found" # => 3 %w[acex].inject(a, &:fetch) rescue "Key not found" # => Key not found %w[x].inject(a, &:fetch) rescue "Key not found" # => Key not found 

Answer 2

 def is_key_present?(hash, key) return true if hash.has_key?(key) hash.each do |k, v| return true if v.kind_of?(Hash) and is_key_present?(v, key) end false end > is_key_present?(a, 'f') => true