在 Ruby 中通过路径替换和访问嵌套 hash/json 中的值

Question

寻求建议您认为使用 ruby​​ 通过路径 ir 变量替换和访问嵌套哈希或 json 中的值的最佳和简单的解决方案是什么？

例如，假设我有具有这种结构的 json 或 hash：

{  
   "name":"John",
   "address":{  
      "street":"street 1",
      "country":"country1"
   },
   "phone_numbers":[  
      {  
         "type":"mobile",
         "number":"234234"
      },
      {  
         "type":"fixed",
         "number":"2342323423"
      }
   ]
}

我想通过可以在变量中指定的路径访问或更改固定手机号码，如下所示：（"phone_numbers/1/number"在这种情况下分隔符并不重要）

此解决方案对于从 json/hash 检索值以及有时通过指定变量的路径来替换变量是必要的。找到了一些可以按键查找值的解决方案，但该解决方案不起作用，因为存在一些哈希/json，其中键名称在多个位置相同。

我看到了这个： https: //github.com/hengguangnan/vine，但是当有效负载像这样时它不起作用，因为在这种情况下它不是一种哈希：

[  
   {  
      "value":"test1"
   },
   {  
      "value":"test2"
   }
] 

希望您有一些解决这个问题的好主意。

谢谢你！

编辑：所以我用这些数据尝试了下面的代码：

    x = JSON.parse('[  
        {  
           "value":"test1"
        },
        {  
           "value":"test2"
        }
     ]')



y = JSON.parse('{  
    "name":"John",
    "address":{  
       "street":"street 1",
       "country":"country1"
    },
    "phone_numbers":[  
       {  
          "type":"mobile",
          "number":"234234"
       },
       {  
          "type":"fixed",
          "number":"2342323423"
       }
    ]
 }')

p x
p y.to_h
p x.get_at_path("0/value") 
p y.get_at_path("name") 

并得到这个：

[{"value"=>"test1"}, {"value"=>"test2"}]
{"name"=>"John", "address"=>{"street"=>"street 1", "country"=>"country1"}, "phone_numbers"=>[{"type"=>"mobile", "number"=>"234234"}, {"type"=>"fixed", "number"=>"2342323423"}]}
hash_new.rb:91:in `<main>': undefined method `get_at_path' for [{"value"=>"test1"}, {"value"=>"test2"}]:Array (NoMethodError)

忘记y.get_at_path("name")​nil

Answer 1

您可以使用 来Hash.dig获取子值，它会继续调用dig每个步骤的结果，直到到达末尾，并且也Array有dig，因此当您到达该数组时，事情将继续工作：

# you said the separator wasn't important, so it can be changed up here
SEPERATOR = '/'.freeze

class Hash
  def get_at_path(path)
    dig(*steps_from(path))
  end

  def replace_at_path(path, new_value)
    *steps, leaf = steps_from path

    # steps is empty in the "name" example, in that case, we are operating on
    # the root (self) hash, not a subhash
    hash = steps.empty? ? self : dig(*steps)
    # note that `hash` here doesn't _have_ to be a Hash, but it needs to
    # respond to `[]=`
    hash[leaf] = new_value
  end

  private
  # the example hash uses symbols as the keys, so we'll convert each step in
  # the path to symbols. If a step doesn't contain a non-digit character,
  # we'll convert it to an integer to be treated as the index into an array
  def steps_from path
    path.split(SEPERATOR).map do |step|
      if step.match?(/\D/)
        step.to_sym
      else
        step.to_i
      end
    end
  end
end

然后就可以这样使用（hash包含您的示例输入）：

p hash.get_at_path("phone_numbers/1/number") # => "2342323423"
p hash.get_at_path("phone_numbers/0/type")   # => "mobile"
p hash.get_at_path("name")                   # => "John"
p hash.get_at_path("address/street")         # => "street 1"

hash.replace_at_path("phone_numbers/1/number", "123-123-1234")
hash.replace_at_path("phone_numbers/0/type", "cell phone")
hash.replace_at_path("name", "John Doe")
hash.replace_at_path("address/street", "123 Street 1")

p hash.get_at_path("phone_numbers/1/number") # => "123-123-1234"
p hash.get_at_path("phone_numbers/0/type")   # => "cell phone"
p hash.get_at_path("name")                   # => "John Doe"
p hash.get_at_path("address/street")         # => "123 Street 1"

p hash
# => {:name=>"John Doe",
#     :address=>{:street=>"123 Street 1", :country=>"country1"},
#     :phone_numbers=>[{:type=>"cell phone", :number=>"234234"},
#                      {:type=>"fixed", :number=>"123-123-1234"}]}