在红宝石/ ActiveRecord的产生Instagram-或类似YouTube的不可猜测的字符串ID [英] Generating an Instagram- or Youtube-like unguessable string ID in ruby/ActiveRecord

问题描述

在创建一个给定的ActiveRecord模型对象的实例，我需要生成一个稍短（6-8个字符）唯一的字符串作为URL的一个标识符来使用，在Instagram的的照片的URL风格（如的http://instagram.com/p/P541i4ErdL/ ，我只是炒是一个404）或YouTube的视频网址（如<一个href="http://www.youtube.com/watch?v=oHg5SJYRHA0">http://www.youtube.com/watch?v=oHg5SJYRHA0).

Upon creating an instance of a given ActiveRecord model object, I need to generate a shortish (6-8 characters) unique string to use as an identifier in URLs, in the style of Instagram's photo URLs (like http://instagram.com/p/P541i4ErdL/, which I just scrambled to be a 404) or Youtube's video URLs (like http://www.youtube.com/watch?v=oHg5SJYRHA0).

什么是去这样做的最好方法是什么？它是最简单的只是创建一个随机字符串反复直到它的独特之处？有没有一种方法散列/洗牌的整数ID以这样一种方式，用户无法改变一个字符（像我一样的404'd的Instagram上面的链接）黑客网址，并最终在一个新的记录？

What's the best way to go about doing this? Is it easiest to just create a random string repeatedly until it's unique? Is there a way to hash/shuffle the integer id in such a way that users can't hack the URL by changing one character (like I did with the 404'd Instagram link above) and end up at a new record?

推荐答案

您可以做这样的事情：

random_attribute.rb 的

module RandomAttribute

  def generate_unique_random_base64(attribute, n)
    until random_is_unique?(attribute)
      self.send(:"#{attribute}=", random_base64(n))
    end
  end

  def generate_unique_random_hex(attribute, n)
    until random_is_unique?(attribute)
      self.send(:"#{attribute}=", SecureRandom.hex(n/2))
    end
  end

  private

  def random_is_unique?(attribute)
    val = self.send(:"#{attribute}")
    val && !self.class.send(:"find_by_#{attribute}", val)
  end

  def random_base64(n)
    val = base64_url
    val += base64_url while val.length < n
    val.slice(0..(n-1))
  end

  def base64_url
    SecureRandom.base64(60).downcase.gsub(/\W/, '')
  end
end
Raw

user.rb 的

class Post < ActiveRecord::Base

  include RandomAttribute
  before_validation :generate_key, on: :create

  private

  def generate_key
    generate_unique_random_hex(:key, 32)
  end
end

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