Collection Cache Keys for ActiveRecord 3.0 - 4.2

This gem is a backport of Rails 5's Relation#cache_key feature, allowing smarter, deterministic caching of ActiveRecord relations.

Add activerecord-collection_cache_key to your Gemfile:

gem 'activerecord-collection_cache_key'

You can now access the key for any ActiveRecord collection via its #cache_key method:

@scope = MyModel.where(active: 1).cache_key

And then use it in your controller:

def index
  @scope = MyModel.where(active: 1)
  Rails.cache.fetch(@scope.cache_key) do
    respond_with(@scope)
  end
end

Notes on Rails 3.x and .all:

In some versions of Rails covered by this gem, Model.all returns an array, and not an instance of ActiveRecord::Relation. In these cases it's possible to access the default key via class method on the model:

MyModel.collection_cache_key

See CONTRIBUTING.md for details

See CHANGELOG.md for details