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Ruby on Rails 5.0 Release Notes

Highlights in Rails 5.0:

  • Action Cable
  • Rails API
  • Active Record Attributes API
  • Test Runner
  • Exclusive use of rails CLI over Rake
  • Sprockets 3
  • Turbolinks 5
  • Ruby 2.2.2+ required

These release notes cover only the major changes. To learn about various bug fixes and changes, please refer to the changelogs or check out the list of commits in the main Rails repository on GitHub.

1. Upgrading to Rails 5.0

If you're upgrading an existing application, it's a great idea to have good test coverage before going in. You should also first upgrade to Rails 4.2 in case you haven't and make sure your application still runs as expected before attempting an update to Rails 5.0. A list of things to watch out for when upgrading is available in the Upgrading Ruby on Rails guide.

2. Major Features

2.1. Action Cable

Action Cable is a new framework in Rails 5. It seamlessly integrates WebSockets with the rest of your Rails application.

Action Cable allows for real-time features to be written in Ruby in the same style and form as the rest of your Rails application, while still being performant and scalable. It's a full-stack offering that provides both a client-side JavaScript framework and a server-side Ruby framework. You have access to your full domain model written with Active Record or your ORM of choice.

See the Action Cable Overview guide for more information.

2.2. API Applications

Rails can now be used to create slimmed down API only applications. This is useful for creating and serving APIs similar to X or GitHub API, that can be used to serve public-facing, as well as, for custom applications.

You can generate a new api Rails app using:

$ rails new my_api --api

This will do three main things:

  • Configure your application to start with a more limited set of middleware than normal. Specifically, it will not include any middleware primarily useful for browser applications (like cookies support) by default.
  • Make ApplicationController inherit from ActionController::API instead of ActionController::Base. As with middleware, this will leave out any Action Controller modules that provide functionalities primarily used by browser applications.
  • Configure the generators to skip generating views, helpers, and assets when you generate a new resource.

The application provides a base for APIs, that can then be configured to pull in functionality as suitable for the application's needs.

See the Using Rails for API-only Applications guide for more information.

2.3. Active Record attributes API

Defines an attribute with a type on a model. It will override the type of existing attributes if needed. This allows control over how values are converted to and from SQL when assigned to a model. It also changes the behavior of values passed to ActiveRecord::Base.where, which let's use our domain objects across much of Active Record, without having to rely on implementation details or monkey patching.

Some things that you can achieve with this:

  • The type detected by Active Record can be overridden.
  • A default can also be provided.
  • Attributes do not need to be backed by a database column.
# db/schema.rb
create_table :store_listings, force: true do |t|
  t.decimal :price_in_cents
  t.string :my_string, default: "original default"
end

# app/models/store_listing.rb
class StoreListing < ActiveRecord::Base
end

store_listing = StoreListing.new(price_in_cents: '10.1')

# before
store_listing.price_in_cents # => BigDecimal.new(10.1)
StoreListing.new.my_string # => "original default"

class StoreListing < ActiveRecord::Base
  attribute :price_in_cents, :integer # custom type
  attribute :my_string, :string, default: "new default" # default value
  attribute :my_default_proc, :datetime, default: -> { Time.now } # default value
  attribute :field_without_db_column, :integer, array: true
end

# after
store_listing.price_in_cents # => 10
StoreListing.new.my_string # => "new default"
StoreListing.new.my_default_proc # => 2015-05-30 11:04:48 -0600
model = StoreListing.new(field_without_db_column: ["1", "2", "3"])
model.attributes # => {field_without_db_column: [1, 2, 3]}

Creating Custom Types:

You can define your own custom types, as long as they respond to the methods defined on the value type. The method deserialize or cast will be called on your type object, with raw input from the database or from your controllers. This is useful, for example, when doing custom conversion, like Money data.

Querying:

When ActiveRecord::Base.where is called, it will use the type defined by the model class to convert the value to SQL, calling serialize on your type object.

This gives the objects ability to specify, how to convert values when performing SQL queries.

Dirty Tracking:

The type of an attribute is allowed to change how dirty tracking is performed.

See its documentation for a detailed write up.

2.4. Test Runner

A new test runner has been introduced to enhance the capabilities of running tests from Rails. To use this test runner simply type bin/rails test.

Test Runner is inspired by RSpec, minitest-reporters, maxitest and others. It includes some of these notable advancements:

  • Run a single test using line number of test.
  • Run multiple tests pinpointing to line number of tests.
  • Improved failure messages, which also add ease of re-running failed tests.
  • Fail fast using -f option, to stop tests immediately on occurrence of failure, instead of waiting for the suite to complete.
  • Defer test output until the end of a full test run using the -d option.
  • Complete exception backtrace output using -b option.
  • Integration with minitest to allow options like -s for test seed data, -n for running specific test by name, -v for better verbose output and so forth.
  • Colored test output.

3. Railties

Please refer to the Changelog for detailed changes.

3.1. Removals

  • Removed debugger support, use byebug instead. debugger is not supported by Ruby 2.2. (commit)

  • Removed deprecated test:all and test:all:db tasks. (commit)

  • Removed deprecated Rails::Rack::LogTailer. (commit)

  • Removed deprecated RAILS_CACHE constant. (commit)

  • Removed deprecated serve_static_assets configuration. (commit)

  • Removed the documentation tasks doc:app, doc:rails, and doc:guides. (commit)

  • Removed Rack::ContentLength middleware from the default stack. (Commit)

3.2. Deprecations

  • Deprecated config.static_cache_control in favor of config.public_file_server.headers. (Pull Request)

  • Deprecated config.serve_static_files in favor of config.public_file_server.enabled. (Pull Request)

  • Deprecated the tasks in the rails task namespace in favor of the app namespace. (e.g. rails:update and rails:template tasks are renamed to app:update and app:template.) (Pull Request)

3.3. Notable changes

  • Added Rails test runner bin/rails test. (Pull Request)

  • Newly generated applications and plugins get a README.md in Markdown. (commit, Pull Request)

  • Added bin/rails restart task to restart your Rails app by touching tmp/restart.txt. (Pull Request)

  • Added bin/rails initializers task to print out all defined initializers in the order they are invoked by Rails. (Pull Request)

  • Added bin/rails dev:cache to enable or disable caching in development mode. (Pull Request)

  • Added bin/update script to update the development environment automatically. (Pull Request)

  • Proxy Rake tasks through bin/rails. (Pull Request, Pull Request)

  • New applications are generated with the evented file system monitor enabled on Linux and macOS. The feature can be opted out by passing --skip-listen to the generator. (commit, commit)

  • Generate applications with an option to log to STDOUT in production using the environment variable RAILS_LOG_TO_STDOUT. (Pull Request)

  • Enable HSTS with IncludeSubdomains header for new applications. (Pull Request)

  • The application generator writes a new file config/spring.rb, which tells Spring to watch additional common files. (commit)

  • Added --skip-action-mailer to skip Action Mailer while generating new app. (Pull Request)

  • Removed tmp/sessions directory and the clear rake task associated with it. (Pull Request)

  • Changed _form.html.erb generated by scaffold generator to use local variables. (Pull Request)

  • Disabled autoloading of classes in production environment. (commit)

4. Action Pack

Please refer to the Changelog for detailed changes.

4.1. Removals

  • Removed ActionDispatch::Request::Utils.deep_munge. (commit)

  • Removed ActionController::HideActions. (Pull Request)

  • Removed respond_to and respond_with placeholder methods, this functionality has been extracted to the responders gem. (commit)

  • Removed deprecated assertion files. (commit)

  • Removed deprecated usage of string keys in URL helpers. (commit)

  • Removed deprecated only_path option on *_path helpers. (commit)

  • Removed deprecated NamedRouteCollection#helpers. (commit)

  • Removed deprecated support to define routes with :to option that doesn't contain #. (commit)

  • Removed deprecated ActionDispatch::Response#to_ary. (commit)

  • Removed deprecated ActionDispatch::Request#deep_munge. (commit)

  • Removed deprecated ActionDispatch::Http::Parameters#symbolized_path_parameters. (commit)

  • Removed deprecated option use_route in controller tests. (commit)

  • Removed assigns and assert_template. Both methods have been extracted into the rails-controller-testing gem. (Pull Request)

4.2. Deprecations

  • Deprecated all *_filter callbacks in favor of *_action callbacks. (Pull Request)

  • Deprecated *_via_redirect integration test methods. Use follow_redirect! manually after the request call for the same behavior. (Pull Request)

  • Deprecated AbstractController#skip_action_callback in favor of individual skip_callback methods. (Pull Request)

  • Deprecated :nothing option for render method. (Pull Request)

  • Deprecated passing first parameter as Hash and default status code for head method. (Pull Request)

  • Deprecated using strings or symbols for middleware class names. Use class names instead. (commit)

  • Deprecated accessing MIME types via constants (e.g. Mime::HTML). Use the subscript operator with a symbol instead (e.g. Mime[:html]). (Pull Request)

  • Deprecated redirect_to :back in favor of redirect_back, which accepts a required fallback_location argument, thus eliminating the possibility of a RedirectBackError. (Pull Request)

  • ActionDispatch::IntegrationTest and ActionController::TestCase deprecate positional arguments in favor of keyword arguments. (Pull Request)

  • Deprecated :controller and :action path parameters. (Pull Request)

  • Deprecated env method on controller instances. (commit)

  • ActionDispatch::ParamsParser is deprecated and was removed from the middleware stack. To configure the parameter parsers use ActionDispatch::Request.parameter_parsers=. (commit, commit)

4.3. Notable changes

  • Added ActionController::Renderer to render arbitrary templates outside controller actions. (Pull Request)

  • Migrating to keyword arguments syntax in ActionController::TestCase and ActionDispatch::Integration HTTP request methods. (Pull Request)

  • Added http_cache_forever to Action Controller, so we can cache a response that never gets expired. (Pull Request)

  • Provide friendlier access to request variants. (Pull Request)

  • For actions with no corresponding templates, render head :no_content instead of raising an error. (Pull Request)

  • Added the ability to override default form builder for a controller. (Pull Request)

  • Added support for API-only apps. ActionController::API is added as a replacement of ActionController::Base for this kind of applications. (Pull Request)

  • Make ActionController::Parameters no longer inherits from HashWithIndifferentAccess. (Pull Request)

  • Make it easier to opt in to config.force_ssl and config.ssl_options by making them less dangerous to try and easier to disable. (Pull Request)

  • Added the ability of returning arbitrary headers to ActionDispatch::Static. (Pull Request)

  • Changed the protect_from_forgery prepend default to false. (commit)

  • ActionController::TestCase will be moved to its own gem in Rails 5.1. Use ActionDispatch::IntegrationTest instead. (commit)

  • Rails generates weak ETags by default. (Pull Request)

  • Controller actions without an explicit render call and with no corresponding templates will render head :no_content implicitly instead of raising an error. (Pull Request 1, 2)

  • Added an option for per-form CSRF tokens. (Pull Request)

  • Added request encoding and response parsing to integration tests. (Pull Request)

  • Add ActionController#helpers to get access to the view context at the controller level. (Pull Request)

  • Discarded flash messages get removed before storing into session. (Pull Request)

  • Added support for passing collection of records to fresh_when and stale?. (Pull Request)

  • ActionController::Live became an ActiveSupport::Concern. That means it can't be just included in other modules without extending them with ActiveSupport::Concern or ActionController::Live won't take effect in production. Some people may be using another module to include some special Warden/Devise authentication failure handling code as well since the middleware can't catch a :warden thrown by a spawned thread which is the case when using ActionController::Live. (More details in this issue)

  • Introduce Response#strong_etag= and #weak_etag= and analogous options for fresh_when and stale?. (Pull Request)

5. Action View

Please refer to the Changelog for detailed changes.

5.1. Removals

  • Removed deprecated AbstractController::Base::parent_prefixes. (commit)

  • Removed ActionView::Helpers::RecordTagHelper, this functionality has been extracted to the record_tag_helper gem. (Pull Request)

  • Removed :rescue_format option for translate helper since it's no longer supported by I18n. (Pull Request)

5.2. Notable Changes

  • Changed the default template handler from ERB to Raw. (commit)

  • Collection rendering can cache and fetches multiple partials at once. (Pull Request, commit)

  • Added wildcard matching to explicit dependencies. (Pull Request)

  • Make disable_with the default behavior for submit tags. Disables the button on submit to prevent double submits. (Pull Request)

  • Partial template name no longer has to be a valid Ruby identifier. (commit)

  • The datetime_tag helper now generates an input tag with the type of datetime-local. (Pull Request)

  • Allow blocks while rendering with the render partial: helper. (Pull Request)

6. Action Mailer

Please refer to the Changelog for detailed changes.

6.1. Removals

  • Removed deprecated *_path helpers in email views. (commit)

  • Removed deprecated deliver and deliver! methods. (commit)

6.2. Notable changes

  • Template lookup now respects default locale and I18n fallbacks. (commit)

  • Added _mailer suffix to mailers created via generator, following the same naming convention used in controllers and jobs. (Pull Request)

  • Added assert_enqueued_emails and assert_no_enqueued_emails. (Pull Request)

  • Added config.action_mailer.deliver_later_queue_name configuration to set the mailer queue name. (Pull Request)

  • Added support for fragment caching in Action Mailer views. Added new config option config.action_mailer.perform_caching to determine whether your templates should perform caching or not. (Pull Request)

7. Active Record

Please refer to the Changelog for detailed changes.

7.1. Removals

  • Removed deprecated behavior allowing nested arrays to be passed as query values. (Pull Request)

  • Removed deprecated ActiveRecord::Tasks::DatabaseTasks#load_schema. This method was replaced by ActiveRecord::Tasks::DatabaseTasks#load_schema_for. (commit)

  • Removed deprecated serialized_attributes. (commit)

  • Removed deprecated automatic counter caches on has_many :through. (commit)

  • Removed deprecated sanitize_sql_hash_for_conditions. (commit)

  • Removed deprecated Reflection#source_macro. (commit)

  • Removed deprecated symbolized_base_class and symbolized_sti_name. (commit)

  • Removed deprecated ActiveRecord::Base.disable_implicit_join_references=. (commit)

  • Removed deprecated access to connection specification using a string accessor. (commit)

  • Removed deprecated support to preload instance-dependent associations. (commit)

  • Removed deprecated support for PostgreSQL ranges with exclusive lower bounds. (commit)

  • Removed deprecation when modifying a relation with cached Arel. This raises an ImmutableRelation error instead. (commit)

  • Removed ActiveRecord::Serialization::XmlSerializer from core. This feature has been extracted into the activemodel-serializers-xml gem. (Pull Request)

  • Removed support for the legacy mysql database adapter from core. Most users should be able to use mysql2. It will be converted to a separate gem when we find someone to maintain it. (Pull Request 1, Pull Request 2)

  • Removed support for the protected_attributes gem. (commit)

  • Removed support for PostgreSQL versions below 9.1. (Pull Request)

  • Removed support for activerecord-deprecated_finders gem. (commit)

  • Removed ActiveRecord::ConnectionAdapters::Column::TRUE_VALUES constant. (commit)

7.2. Deprecations

  • Deprecated passing a class as a value in a query. Users should pass strings instead. (Pull Request)

  • Deprecated returning false as a way to halt Active Record callback chains. The recommended way is to throw(:abort). (Pull Request)

  • Deprecated ActiveRecord::Base.errors_in_transactional_callbacks=. (commit)

  • Deprecated Relation#uniq use Relation#distinct instead. (commit)

  • Deprecated the PostgreSQL :point type in favor of a new one which will return Point objects instead of an Array (Pull Request)

  • Deprecated force association reload by passing a truthy argument to association method. (Pull Request)

  • Deprecated the keys for association restrict_dependent_destroy errors in favor of new key names. (Pull Request)

  • Synchronize behavior of #tables. (Pull Request)

  • Deprecated SchemaCache#tables, SchemaCache#table_exists? and SchemaCache#clear_table_cache! in favor of their new data source counterparts. (Pull Request)

  • Deprecated connection.tables on the SQLite3 and MySQL adapters. (Pull Request)

  • Deprecated passing arguments to #tables - the #tables method of some adapters (mysql2, sqlite3) would return both tables and views while others (postgresql) just return tables. To make their behavior consistent, #tables will return only tables in the future. (Pull Request)

  • Deprecated table_exists? - The #table_exists? method would check both tables and views. To make their behavior consistent with #tables, #table_exists? will check only tables in the future. (Pull Request)

  • Deprecate sending the offset argument to find_nth. Please use the offset method on relation instead. (Pull Request)

  • Deprecated {insert|update|delete}_sql in DatabaseStatements. Use the {insert|update|delete} public methods instead. (Pull Request)

  • Deprecated use_transactional_fixtures in favor of use_transactional_tests for more clarity. (Pull Request)

  • Deprecated passing a column to ActiveRecord::Connection#quote. (commit)

  • Added an option end to find_in_batches that complements the start parameter to specify where to stop batch processing. (Pull Request)

7.3. Notable changes

  • Added a foreign_key option to references while creating the table. (commit)

  • New attributes API. (commit)

  • Added :_prefix/:_suffix option to enum definition. (Pull Request, Pull Request)

  • Added #cache_key to ActiveRecord::Relation. (Pull Request)

  • Changed the default null value for timestamps to false. (commit)

  • Added ActiveRecord::SecureToken in order to encapsulate generation of unique tokens for attributes in a model using SecureRandom. (Pull Request)