Simple, simple method caching for ActiveRecord models

Cacheable.md

Cacheable

Simple, simple method caching for ActiveRecord models.

Example

class User < ActiveRecord::Base
  include Cacheable
  
  def related_events
    Event.expensive_relationships_finder_for(self)
  end
  cache_method :related_events, to_a: true
end

Options

• :key - Optional time column to use for the cache_key method. Must respond to utc.to_s(:number)
• :to_a - Should we call to_a on the results?

cacheable.rb

module Cacheable
  extend ActiveSupport::Concern

  module ClassMethods
    def cache_method(method, options={})
      opts = {key: :updated_at, to_a: false}.merge(options)
      define_method "fetch_#{method}" do
        fetch_key = [cache_key(opts[:key]), method]
        Rails.cache.fetch(fetch_key) do
          results = self.send(method)
          if opts[:to_a] && results.respond_to?(:to_a)
            results.to_a
          else
            results
          end
        end
      end
    end
  end

  def cache_key(attribute=:updated_at)
    case
    when new_record?
      "#{self.class.model_name.cache_key}/new"
    when timestamp = self[attribute]
      timestamp = timestamp.utc.to_s(:number)
      "#{self.class.model_name.cache_key}/#{id}-#{timestamp}"
    else
      "#{self.class.model_name.cache_key}/#{id}"
    end
  end
end