PackRat

PackRat is a simple helper for Rails.cache
When included in your class it makes caching trivial.

class MyClass
  include PackRat::CacheHelper

  def some_method
    cache do
      #stuff
    end
  end

  def self.some_class_method
    cache do
      # stuff
    end
  end
end

Installation

To install:

gem install pack_rat

or include in your Gemfile

gem 'pack_rat'

PackRat::CacheHelper does a few things:

• Adds a cache_key method to your class, which takes your most recently updated record (assuming a model here) and calls it's cache_key, and adds your classes name
  Right now cache_key assumes you are using ActiveRecord as your ORM, but you can overwrite this
• Adds a few of class attrs:
  • file_location - Defaults to using your model's name to determine the file's path, you can set this manually in your class self.file_location = '/path/to/file'
  • updated_attribute_name - Defaults to :updated_at, this is used for your class's cache_key method, self.updated_attribute_name = :my_custom_attr
  • file_digest - When your class is first loaded an MD5 digest is created, based on file_location, this ensures that if your class changes, your caches automatically expire
• Adds a cache method to your class and your instances
  cache uses the calling method name, your class's md5 digest, and the calling context's cache_key method
  You can pass in some options:
  • overwrite_key - When set, whatever key is passed into cache will overwrite the automatically generated key
    If a key is provided and overwrite_key is not set, it will get added to the auto generated key
  • debug - When set, will output the generated cache key to the console
  • accepts all other options available to Rails.cache.fetch

When included into your gemfile, PackRat is automatically included into ActiveRecord::Base

If you do not want an MD5 digest created, then set self.file_location = nil in your class.

Check it out. Use the debug: true option in your cache call to see what key is actually being generated for debugging

def some_method
  cache '', debug: true do
    # stuff
  end
end

An Example using an ActiveRecord class

class MyClass < ActiveRecord::Base

  def my_long_instance_method
    cache do
      puts 'stuff'
    end
  end

  def self.my_long_class_method
    cache do
      puts 'stuff'
    end
  end

  def method_with_debug
    cache [], debug: true do
      puts 'stuff'
    end
  end

  def self.class_method_with_debug
    cache [], debug: true do
      puts 'stuff'
    end
  end
end

If you are passing in options, you must specify a cache key, this can be an empty string, or an empty array, or even not empty, but it has to be there

Contributing to pack_rat

• Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet.
• Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it.
• Fork the project.
• Start a feature/bugfix branch.
• Commit and push until you are happy with your contribution.
• Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.
• Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.

Copyright

Copyright (c) 2013 Brian Goff. See LICENSE.txt for further details.