A gem for caching HTTP responses.

The gem was built with an idea to implement a class which will create options for the ActionController::ConditionalGet#stale? method. It allows to cache any kind of objects, not only records or collections (unlike of #stale?).

• Installation
• Usage
  • Caching options
  • Examples
  • Controller helpers
• Contributing
• License

Add one of these lines to your application's Gemfile depending on your Rails version:

# Rails 5.2
gem 'stale_options', '~> 1.0.0'

# Rails 6.0
gem 'stale_options', '~> 1.1.0'

# Rails 6.1
gem 'stale_options', '~> 1.2.0'

# Rails 7.0
gem 'stale_options', '~> 1.3.0'

And then execute:

bundle install

StaleOptions.create(Item.all)
=> {:etag=>"39f08c583b023142dd64b0922dfaefd4", :last_modified=>2018-07-04 18:05:22 UTC}

The method accepts an optional second parameter (see Caching options).

There are two options for caching, cache_by and last_modified:

• :cache_by
  • String or Symbol. The name of the method that returns the unique identifier of the object for caching, which is used to set etag of the resulting options. Set it to itself if you don't have such a method (see example below) and the gem will generate etag for you.
  • Default: :updated_at.
• :last_modified
  • String or Symbol. The name of the method that returns an instance of ActiveSupport::TimeWithZone, DateTime or Time.
  • ActiveSupport::TimeWithZone, DateTime, Time or nil to set :last_modified directly.
  • Default: :updated_at.

StaleOptions.create(Task.all, last_modified: :done_at)
=> {:etag=>"ce8d2fbc9b815937b59e8815d8a85c21", :last_modified=>2018-06-30 18:25:07 UTC}

StaleOptions.create([1, 2, 3], cache_by: :itself, last_modified: nil)
=> {:etag=>"73250e72da5d8950b6bbb16044353d26", :last_modified=>nil}

StaleOptions.create({ a: 'a', b: 'b', c: 'c' }, cache_by: :itself, last_modified: Time.now)
=> {:etag=>"fec76eca1192bc7371e44d517b56c93f", :last_modified=>2018-07-08 07:08:48 UTC}

In your controller:

# To render a template:

class PostsController < ApplicationController
  include StaleOptions::Backend

  def index
    if_stale?(Post.all) do |posts|
      @posts = posts
    end
  end
end

# Or, to render json:

class PostsController < ApplicationController
  include StaleOptions::Backend

  def index
    if_stale?(Post.all) do |posts|
      render json: posts
    end
  end
end

Here we're using the #if_stale? method which was added to the controller by including the StaleOptions::Backend module. The method accepts two arguments record and options (yeah, just like StaleOptions.create).

Under the hood, it calls ActionController::ConditionalGet#stale? with options created by StaleOptions.create:

def if_stale?(record, options = {})
  yield(record) if stale?(StaleOptions.create(record, options))
end

Bug reports and pull requests are welcome on GitHub at https://github.com/digaev/stale_options.

The gem is available as open source under the terms of the MIT License.