如何访问嵌套散列/数组中的元素，给定类似“a.b.0.x”的路径？

path = "a.b.0.x" 
path.split('.').reduce(target) do |acc, val| 
    case acc 
    when Array 
    break nil unless /\A\d+\z/ === val 
    acc[val.to_i] 
    when Hash 
    next acc[val.to_i] if /\A\d+\z/ === val && acc[val.to_i] 
    acc[val] || acc[val.to_sym] 
    else break nil 
    end 
end rescue nil 
#⇒ "here" 

鉴于这种访问的边缘情况，我建议创建一个新的类来处理这种情况并将输入均匀化为一致的结构。在这种情况下，Hash（可能更边缘的情况下评论欢迎）

class DepthAccessor 
    class AccessFailure < StandardError 
    def initialize(val,current=nil,full=nil,depth=nil) 
     super(
     if full && depth 
      "Failed to find #{val.inspect} for #{current.inspect}:#{current.class} in #{full.inspect} at depth #{depth}" 
     else 
      val 
     end 
    ) 
    end 
    end 
    def initialize(target) 
    raise ArgumentError, "#{target.inspect}:#{target.class} must respond_to :each_with_object" unless target.respond_to?(:each_with_object) 
    @target = homogenize(target) 
    end 
    def path_search(path,sep: '.',raise_on_fail: true) 
    split_path = path.split(sep) 
    split_path.each_with_index.inject(@target) do |acc,(val,idx)| 
     begin 
     acc.is_a?(Hash) ? acc[val] : raise 
     rescue StandardError 
     if raise_on_fail 
      raise AccessFailure.new(val,acc,@target,split_path[0..idx].join(sep)) 
     else 
      nil 
     end 
     end 
    end 
    end 
    private 
    def homogenize(val) 
     case val 
     when Array 
      val.each_with_index.with_object({}) {|(v,idx),obj| obj[idx.to_s] = homogenize(v) } 
     when Hash 
      val.each_with_object({}) { |(k,v),obj| obj[k.to_s] = homogenize(v) } 
     else 
      val 
     end 
    end 
end 

当你创建一个新的实例中的所有键都转换为Strings和所有Array转换为使用index为key

Hash ES

然后使用这样

target = { 
    :a => { 
    "b" => [ 
     { 
     :x => "here" 
     } 
    ] 
    } 
} 
DepthAccessor.new(target).path_search('a.b.0.x') 
#=> "here" 
DepthAccessor.new(target).path_search('a.b.c.x') 
#=> Failed to find "c" for {"0"=>{"x"=>"here"}}:Hash in {"a"=>{"b"=>{"0"=>{"x"=>"here"}}}} at depth a.b.c 

Full Example

如果Array小号的预订要求那么这里是另一个例子（有一些额外的功能）Example