Rails acts-as-keyed updated/simplified

concerns-keyed_model.rb

# Largely based on `acts-as-keyed` but with less magic (namely make `to_param` consistent, don't overwrite `find`)
# https://github.com/jhubert/acts-as-keyed
# http://vaidehijoshi.github.io/blog/2015/10/13/stop-worrying-and-start-being-concerned-activesupport-concerns/
module KeyedModel
  extend ActiveSupport::Concern

  KEY_CREATION_RETRIES = 100
  KEY_LENGTH = 8

  included do
    if ActiveRecord::Base.connection.table_exists?(self.table_name) && columns_hash["key"].nil?
      raise "Missing `key` column. Please ensure it was added in a migration via generator (easiest for UNIQUE index)"
    end

    before_validation(:create_key, :on => :create)
  end

  class_methods do
    # DEV: We don't extend `find` so we don't back ourselves into a corner with type inference
    #   An example failure would be moving to UUIDs which are also string based
    #   it would make a lot of replacements for `find` or add computation complexity
    def key_exists?(key_val)
      return exists?(:key => key_val)
    end

    def generate_key()
      # http://api.rubyonrails.org/classes/SecureRandom.html
      # A-Z, a-z, 0-9 except for visually similar characters (i.e. 0 vs O, I vs l)
      return SecureRandom.base58(KEY_LENGTH)
    end

    def from_param(param)
      return find_by_key!(param)
    end
  end

  def to_param
    return self.key
  end

  protected
  def create_key
    key_val = nil
    KEY_CREATION_RETRIES.times do
      key_val = self.class.generate_key()
      break if not self.class.key_exists? key_val
      key_val = nil
    end
    if key_val.nil?
      raise "Could not find unique key in #{KEY_CREATION_RETRIES} tries. Please expand `key` size for #{self.class.name}"
    end
    self.key = key_val
  end
end