Ettu

Using Rails 4's stale? or fresh_when? Are your users seeing old view code even after new deploys? The Rails way fresh_when(@product) doesn't account for changes in your view code, you have to do it yourself.

Ettu (loosely translated "And calculate you, too?") transparently accounts for the current action's view code (JavaScript, CSS, templates) using the same [asset fingerprinting] (http://guides.rubyonrails.org/asset_pipeline.html#what-is-fingerprinting-and-why-should-i-care-questionmark) and Russian Doll [template cache digesting] (https://github.com/rails/cache_digests#readme) used by Rails. It does all of this while allowing you to use the same syntax you're already accustomed to. So keep doing what you're doing, and let Ettu worry about changes to your view code.

Have a Rails 3 project? The [v3 branch] (https://github.com/cloudspace/ettu/tree/v3) (and 3.* releases) are set up to support it.

Add Ettu to your Gemfile:

gem 'ettu'

And $ bundle install

Rails ETags can be used in the following way:

class ProductsController < ApplicationController
  def show
    @product = Product.find(params[:id])

    # Sugar syntax
    fresh_when @product

    # Hash syntax
    fresh_when etag: @product, last_modified: @product.updated_at, public: true
  end
end

Ettu wants you to keep using either syntax, and let it worry about the view code. By default, it will add in the fingerprints of your precompiled assets along with the cache digest of the current action into the calculation for the final ETag sent to the browser.

Ettu can be disabled for any environment using the ettu.disabled config option.

# config/environments/*.rb
My::Application.configure do
  config.ettu.disabled = true
end

Of course, you can override Ettu's default behavior:

# config/initializers/ettu.rb
Ettu.configure do |config|
  # Add in extra assets to account for
  config.assets += ['first.js', 'second.css']
end

Or each can be passed on an individual basis:

fresh_when @product, assets: 'super.css'

Additionally, you can specify a different template to calculate with the view option:

fresh_when @product, view: 'products/index'

You can even stop Ettu from accounting for any of them by setting the value to false:

fresh_when @product, assets: false, view: false

Ettu tries its darndest to not interfere with Rails' default implementation. Ettu makes sure to pass all the options you specify to Rails (like the public option). It's even coded as a drop-in gem that won't cause problems if it's not installed.

In order for Rails to detect changes to templates when testing perform_caching in the development environment, you must disable cache_template_loading.

# config/environments/development.rb
My::Application.configure do
  config.action_view.cache_template_loading = false
end

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Code your feature, and add specs for it
4. Commit your changes (git commit -am 'Add some feature')
5. Push to the branch (git push origin my-new-feature)
6. Create new Pull Request