递归从哈希去除`nil`和空值

Question

我有开始作为一个哈希：

{"request"=>{
  "security"=>{"username"=>{"type"=>nil}, "password"=>{"type"=>nil}},
  "order_i_d"=>{"type"=>nil, "description"=>nil},
  "order_number"=>{"type"=>nil},
  "show_kit_as_individual_s_k_us"=>false,
  "website_i_d"=>{"type"=>nil, "description"=>nil}
}}

我想递归删除是nil?和empty?所有值，但留在原地的falsey值。最终的结果应该是这样的：

{"request"=>{
  "show_kit_as_individual_s_k_us"=>false
}}

我怎样才能做到这一点？

Answer 1

只是另一种实现，为乐趣和实践编写的。

• 没有猴子补丁
• 工程于哈希和数组
• 可作为一个模块的功能，如：DeepCompact.deep_compact(hash)
• 也具有破坏性目标修改的变体：DeepCompact.deep_compact!(hash)
• 可以使用由现有的对象上延伸：{ foo: nil }.extend(DeepCompact).deep_compact
• 可以通过改进可以使用：将using DeepCompact到文件/类会带来deep_compact和deep_compact!到散列和数组在该文件/类的所有代码。

这里的模块：

module DeepCompact
  [Hash, Array].each do |klass|
    refine klass do
      def deep_compact
        DeepCompact.deep_compact(self)
      end

      def deep_compact!
        DeepCompact.deep_compact!(self)
      end
    end
  end

  def self.extended(where)
    where.instance_exec do
      def deep_compact
        DeepCompact.deep_compact(self)
      end

      def deep_compact!
        DeepCompact.deep_compact!(self)
      end
    end
  end

  def deep_compact(obj)
    case obj
    when Hash
      obj.each_with_object({}) do |(key, val), obj|
        new_val = DeepCompact.deep_compact(val)
        next if new_val.nil? || (new_val.respond_to?(:empty?) && new_val.empty?)
        obj[key] = new_val
      end
    when Array
      obj.each_with_object([]) do |val, obj|
        new_val = DeepCompact.deep_compact(val)
        next if new_val.nil? || (new_val.respond_to?(:empty?) && new_val.empty?)
        obj << val
      end
    else
      obj
    end
  end
  module_function :deep_compact

  def deep_compact!(obj)
    case obj
    when Hash
      obj.delete_if do |_, val|
        val.nil? || (val.respond_to?(:empty?) && val.empty?) || DeepCompact.deep_compact!(val)
      end
      obj.empty?
    when Array
      obj.delete_if do |val|
        val.nil? || (val.respond_to?(:empty?) && val.empty?) || DeepCompact.deep_compact!(val)
      end
      obj.empty?
    else
      false
    end
  end
  module_function :deep_compact!
end

然后就如何使用它的一些例子：

hsh = {
  'hello' => [
    'world',
    { 'and' => nil }
  ],
  'greetings' => nil,
  'salutations' => {
    'to' => { 'you' => true, 'him' => 'yes', 'her' => nil },
     'but_not_to' => nil
  }
}

puts "Original:"
pp hsh
puts
puts "Non-destructive module function:"
pp DeepCompact.deep_compact(hsh)
puts
hsh.extend(DeepCompact)
puts "Non-destructive after hash extended:"
pp hsh.deep_compact
puts
puts "Destructive refinement for array:"
array = [hsh]
using DeepCompact
array.deep_compact!
pp array

和输出：

Original:
{"hello"=>["world", {"and"=>nil}],
 "greetings"=>nil,
 "salutations"=>
  {"to"=>{"you"=>true, "him"=>"yes", "her"=>nil}, "but_not_to"=>nil}}

Non-destructive module function:
{"hello"=>["world"], "salutations"=>{"to"=>{"you"=>true, "him"=>"yes"}}}

Non-destructive after hash extended:
{"hello"=>["world"], "salutations"=>{"to"=>{"you"=>true, "him"=>"yes"}}}

Destructive refinement for array:
[{"hello"=>["world"], "salutations"=>{"to"=>{"you"=>true, "him"=>"yes"}}}]

或者只是使用了多种宝石为你提供这种之一。

Answer 2

提出了以下几点：

class Hash  
  def deep_compact!
    self.each_pair do |key, value|
      if value.is_a?(Hash)
        value.deep_compact!
      end
      if value.nil? || (value.is_a?(Hash) && value.empty?)
        self.delete(key)
      end
    end
  end
end

Answer 3

另外一个选项：

class Hash
    def deep_transform(&block)
      self.inject({}){|result, (key,value)|
        value = if Hash === value
                  value.deep_transform(&block)
                else
                  value
                end
        block.call(result,key,value)
        result
      }
    end

    def deep_compact
      self.deep_transform do |result, key, value|
        if value.nil? || (value.is_a?(Hash) && value.empty?)
          # Don't Keep
        else
          result[key] = value
        end
      end
    end
end