rails_42_upgrade.org

Upgrading from Rails 4.1 to Rails 4.2

Web Console [1/1]

First, add gem 'web-console', '~> 2.0' to the :development group in your Gemfile and run bundle install (it won’t have been included when you upgraded Rails). Once it’s been installed, you can simply drop a reference to the console helper (i.e., <% console %>=) into any view you want to enable it for. A console will also be provided on any error page you view in your development environment.

[X] Added web-console

Responders [1/1]

respond_with and the class-level respond_to methods have been extracted to the responders gem. To use them, simply add gem 'responders', '~> 2.0' to your Gemfile. Calls to respond_with and respond_to (again, at the class level) will no longer work without having included the responders gem in your dependencies:

# app/controllers/users_controller.rb

class UsersController < ApplicationController
  respond_to :html, :json

  def show
    @user = User.find(params[:id])
    respond_with @user
  end
end

Instance-level respond_to is unaffected and does not require the additional gem:

# app/controllers/users_controller.rb

class UsersController < ApplicationController
  def show
    @user = User.find(params[:id])
    respond_to do |format|
      format.html
      format.json { render json: @user }
    end
  end
end

See #16526 for more details.

[X] Removed one class level respond_to

Error handling in transaction callbacks [1/1]

Currently, Active Record suppresses errors raised within after_rollback or after_commit callbacks and only prints them to the logs. In the next version, these errors will no longer be suppressed. Instead, the errors will propagate normally just like in other Active Record callbacks.

When you define a after_rollback or after_commit callback, you will receive a deprecation warning about this upcoming change. When you are ready, you can opt into the new behavior and remove the deprecation warning by adding following configuration to your config/application.rb:

config.active_record.raise_in_transactional_callbacks = true

See #14488 and #16537 for more details.

[X] Added config.active_record.raise_in_transactional_callbacks = true

Ordering of test cases [1/1]

In Rails 5.0, test cases will be executed in random order by default. In anticipation of this change, Rails 4.2 introduced a new configuration option active_support.test_order for explicitly specifying the test ordering. This allows you to either lock down the current behavior by setting the option to :sorted, or opt into the future behavior by setting the option to :random.

If you do not specify a value for this option, a deprecation warning will be emitted. To avoid this, add the following line to your test environment:

# config/environments/test.rb
Rails.application.configure do
  config.active_support.test_order = :sorted # or `:random` if you prefer
end

[X] Add to test.rb

Serialized attributes [1/1]

When using a custom coder (e.g. serialize :metadata, JSON), assigning nil to a serialized attribute will save it to the database as NULL instead of passing the nil value through the coder (e.g. "null" when using the JSON coder).

[X] I’m not aware how this could affect us

Production log level [1/1]

In Rails 5, the default log level for the production environment will be changed to :debug (from :info). To preserve the current default, add the following line to your production.rb:

# Set to `:info` to match the current default, or set to `:debug` to opt-into
# the future default.
config.log_level = :info

[X] We controll the log level already

`after_bundle` in Rails templates []

If you have a Rails template that adds all the files in version control, it fails to add the generated binstubs because it gets executed before Bundler:

# template.rb
generate(:scaffold, "person name:string")
route "root to: 'people#index'"
rake("db:migrate")

git :init
git add: "."
git commit: %Q{ -m 'Initial commit' }

You can now wrap the git calls in an after_bundle block. It will be run after the binstubs have been generated.

# template.rb
generate(:scaffold, "person name:string")
route "root to: 'people#index'"
rake("db:migrate")

after_bundle do
  git :init
  git add: "."
  git commit: %Q{ -m 'Initial commit' }
end

[X] We don’t use Rails application templates

Rails HTML Sanitizer [1/1]

There’s a new choice for sanitizing HTML fragments in your applications. The venerable html-scanner approach is now officially being deprecated in favor of =Rails HTML Sanitizer=.

This means the methods sanitize, sanitize_css, strip_tags and strip_links are backed by a new implementation.

This new sanitizer uses Loofah internally. Loofah in turn uses Nokogiri, which wraps XML parsers written in both C and Java, so sanitization should be faster no matter which Ruby version you run.

The new version updates sanitize, so it can take a Loofah::Scrubber for powerful scrubbing. See some examples of scrubbers here.

Two new scrubbers have also been added: PermitScrubber and TargetScrubber. Read the gem’s readme for more information.

The documentation for PermitScrubber and TargetScrubber explains how you can gain complete control over when and how elements should be stripped.

If your application needs to use the old sanitizer implementation, include rails-deprecated_sanitizer in your Gemfile:

gem 'rails-deprecated_sanitizer'

[X] Not sure how this would affect us

Rails DOM Testing [1/1]

The =TagAssertions= module (containing methods such as assert_tag), has been deprecated in favor of the assert_select methods from the SelectorAssertions module, which has been extracted into the rails-dom-testing gem.

[X] To my understanding we are not using this. Couldn’t find anything with grep assert_tag

Masked Authenticity Tokens [1/1]

In order to mitigate SSL attacks, form_authenticity_token is now masked so that it varies with each request. Thus, tokens are validated by unmasking and then decrypting. As a result, any strategies for verifying requests from non-rails forms that relied on a static session CSRF token have to take this into account.

[X] To my understanding this doesn’t affect us

Action Mailer [1/1]

Previously, calling a mailer method on a mailer class will result in the corresponding instance method being executed directly. With the introduction of Active Job and #deliver_later, this is no longer true. In Rails 4.2, the invocation of the instance methods are deferred until either deliver_now or deliver_later is called. For example:

class Notifier < ActionMailer::Base
  def notify(user, ...)
    puts "Called"
    mail(to: user.email, ...)
  end
end

mail = Notifier.notify(user, ...) # Notifier#notify is not yet called at this point
mail = mail.deliver_now           # Prints "Called"

This should not result in any noticeable differences for most applications. However, if you need some non-mailer methods to be executed synchronously, and you were previously relying on the synchronous proxying behavior, you should define them as class methods on the mailer class directly:

class Notifier < ActionMailer::Base
  def self.broadcast_notifications(users, ...)
    users.each { |user| Notifier.notify(user, ...) }
  end
end

[X] Changed CommunityMailer

Foreign Key Support [1/1]

The migration DSL has been expanded to support foreign key definitions. If you’ve been using the Foreigner gem, you might want to consider removing it. Note that the foreign key support of Rails is a subset of Foreigner. This means that not every Foreigner definition can be fully replaced by its Rails migration DSL counterpart.

The migration procedure is as follows:

remove gem "foreigner" from the Gemfile.
run bundle install.
run bin/rake db:schema:dump.
make sure that db/schema.rb contains every foreign key definition with the necessary options.

[X] We haven’t been using Foreigner gem

rap1ds/rails_42_upgrade.org