Comprehensive cache key generator (complements Rails cache helper)

How to design a perfect cache key? This project's goal is to provide the bulletproof solution for most use cases.

cache_key_for is a Railtie. We support the versions of Ruby and Rails listed in .travis.yml.

It should be run as a gem and included in your Gemfile:

gem "cache_key_for"

Features:

• ORM agnostic

• works with arrays and Plain Old Ruby Objects (POROs) (just provide: #id, #updated_at)

• supports locale

• recognizes subdomains

• deletion from and addition to collections sorted in ascending order (via embedded count in the key)

• accepts cache_owner_cache_key for personalized cache, eg. current_company.cache_key, current_user.cache_key etc.

• filters params with proper non-utf8 data handling for key generation

• supports paginated and not paginated collections or arrays of objects

• recognizes pagination via params (performs well for less than 100 objects per page)

• allows to set default page and per_page or sort order or any param in default_params to avoid multiple different default caches

• includes all params, not only GET's query params, which enables submitting of complex forms via POST, which - otherwise - would have query string longer than 2048 characters (Microsoft Internet Explorer)

• optional whitelist of first level parameters to prevent accidentally generating duplicated cache

• strips utm_* params

• optional suffix for:

  • expiry tags (unlike :expires_in cache option, this offers full :file_store storage compatibility)
  • any edge cases

• file differentiation and file changes are handled separately by Rails' cache helper (md5 is added at the end of cache path)

• one key instead of many, but also unobtrusive (example in haml):

  - cache [cache_key_for(@articles, 'articles'), @some_active_model_object, 'box-type-view'] do
  (...)

• core concept of Russian Doll Caching is touching: belongs_to :some_model, touch: true, but if you do not use touch, you can still cache safely like this (example in haml):

  - cache [cache_key_for(@articles, 'articles'), @some_model_instance] do
  (...)

Example (haml):

- cache cache_key_for(@service.datacenters, 'datacenters', current_company.cache_key, Time.now.utc.to_date.to_s) do
(...)

Rails will generate cache at:

app_name:views/en/datacenters/5bd92bd352e7726d02175752913014711f5d412e/companies/1-20150619101645935901000/2015-06-26/7a6f89a738006a69c1d1e0214e147bab

Features:

• all features of cache_key_for method
• better debugging (accepts view/partial file path for visible part of cache key)

Example (haml):

- cache cache_key_for_view(__FILE__, @service.datacenters, 'datacenters', current_company.cache_key, Time.now.utc.to_date.to_s) do
(...)

Rails will generate cache at:

app_name:views/en/datacenters/5bd92bd352e7726d02175752913014711f5d412e/companies/1-20150619101645935901000/2015-06-
26/app/views/services/datacenters.html.haml/4324f99340fd2b2bc7e26b8e9b79d8f5

./bin/setup
bundle exec rake

rm gemfiles/*.lock
bundle exec appraisal install

• implement https://robots.thoughtbot.com/ruby-2-keyword-arguments to simplify passing custom args