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Ruby on Rails 4.1 Release Notes

Highlights in Rails 4.1:

  • Variants
  • Action View extracted from Action Pack

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

Upgrading to Rails 4.1

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 4.0 in case you haven't and make sure your application still runs as expected before attempting an update to Rails 4.1. A list of things to watch out for when upgrading is available in the Upgrading to Rails guide.

Major Features

  • Variants

    We often want to render different html/json/xml templates for phones, tablets, and desktop browsers. Variants make it easy.

    The request variant is a specialization of the request format, like :tablet, :phone, or :desktop.

    You can set the variant in a before_action:

      request.variant = :tablet if request.user_agent =~ /iPad/

    Respond to variants in the action just like you respond to formats:

      respond_to do |format|
        format.html do |html|
          html.tablet # renders app/views/projects/show.html+tablet.erb
 { extra_setup; render ... }

    Provide separate templates for each format and variant:




Please refer to the Changelog for detailed changes.


  • Removed update:application_controller rake task.

  • Removed deprecated Rails.application.railties.engines.

  • Removed deprecated threadsafe! from Rails Config.

  • Removed deprecated ActiveRecord::Generators::ActiveModel#update_attributes in favor of ActiveRecord::Generators::ActiveModel#update

  • Removed deprecated config.whiny_nils option

  • Removed deprecated rake tasks for running tests: rake test:uncommitted and rake test:recent.

Notable changes

  • BACKTRACE environment variable to show unfiltered backtraces for test failures. (Commit)

  • Exposed MiddlewareStack#unshift to environment configuration. (Pull Request)

Action Mailer

Please refer to the Changelog for detailed changes.

Notable changes

  • Instrument the generation of Action Mailer messages. The time it takes to generate a message is written to the log. (Pull Request)

Active Model

Please refer to the Changelog for detailed changes.


  • Deprecate Validator#setup. This should be done manually now in the validator's constructor. (Commit)

Notable changes

  • Added new API methods reset_changes and changes_applied to ActiveModel::Dirty that control changes state.

Active Support

Please refer to the Changelog for detailed changes.


  • Removed deprecated String#encoding_aware? core extensions (core_ext/string/encoding).

  • Removed deprecated Module#local_constant_names in favor of Module#local_constants.

  • Removed deprecated DateTime.local_offset in favor of DateTime.civil_from_fromat.

  • Removed deprecated Logger core extensions (core_ext/logger.rb).

  • Removed deprecated Time#time_with_datetime_fallback, Time#utc_time and Time#local_time in favor of Time#utc and Time#local.

  • Removed deprecated Hash#diff with no replacement.

  • Removed deprecated Date#to_time_in_current_zone in favor of Date#in_time_zone.

  • Removed deprecated Proc#bind with no replacement.

  • Removed deprecated Array#uniq_by and Array#uniq_by!, use native Array#uniq and Array#uniq! instead.

  • Removed deprecated ActiveSupport::BasicObject, use ActiveSupport::ProxyObject instead.

  • Removed deprecated BufferedLogger, use ActiveSupport::Logger instead.

  • Removed deprecated assert_present and assert_blank methods, use assert object.blank? and assert object.present? instead.


  • Deprecated Numeric#{ago,until,since,from_now}, the user is expected to explicitly convert the value into an AS::Duration, i.e. 5.ago => 5.seconds.ago (Pull Request)

Notable changes

  • Added ActiveSupport::Testing::TimeHelpers#travel and #travel_to. These methods change current time to the given time or time difference by stubbing and (Pull Request)

  • Added Numeric#in_milliseconds, like 1.hour.in_milliseconds, so we can feed them to JavaScript functions like getTime(). (Commit)

  • Added Date#middle_of_day, DateTime#middle_of_day and Time#middle_of_day methods. Also added midday, noon, at_midday, at_noon and at_middle_of_day as aliases. (Pull Request)

  • Added String#remove(pattern) as a short-hand for the common pattern of String#gsub(pattern,''). (Commit)

  • Removed 'cow' => 'kine' irregular inflection from default inflections. (Commit)

Action Pack

Please refer to the Changelog for detailed changes.


  • Removed deprecated Rails application fallback for integration testing, set ActionDispatch.test_app instead.

  • Removed deprecated page_cache_extension config.

  • Removed deprecated constants from Action Controller:

    ActionController::AbstractRequest => ActionDispatch::Request ActionController::Request => ActionDispatch::Request ActionController::AbstractResponse => ActionDispatch::Response ActionController::Response => ActionDispatch::Response ActionController::Routing => ActionDispatch::Routing ActionController::Integration => ActionDispatch::Integration ActionController::IntegrationTest => ActionDispatch::IntegrationTest

Notable changes

  • Take a hash with options inside array in #url_for. (Pull Request)

  • Added session#fetch method fetch behaves similarly to Hash#fetch, with the exception that the returned value is always saved into the session. (Pull Request)

  • Separated Action View completely from Action Pack. (Pull Request)

Active Record

Please refer to the Changelog for detailed changes.


  • Removed deprecated nil-passing to the following SchemaCache methods: primary_keys, tables, columns and columns_hash.

  • Removed deprecated block filter from ActiveRecord::Migrator#migrate.

  • Removed deprecated String constructor from ActiveRecord::Migrator.

  • Removed deprecated scope use without passing a callable object.

  • Removed deprecated transaction_joinable= in favor of begin_transaction with d:joinable option.

  • Removed deprecated decrement_open_transactions.

  • Removed deprecated increment_open_transactions.

  • Removed deprecated PostgreSQLAdapter#outside_transaction? methodd. You can use #transaction_open? instead.

  • Removed deprecated ActiveRecord::Fixtures.find_table_name in favor of ActiveRecord::Fixtures.default_fixture_model_name.

  • Removed deprecated columns_for_remove from SchemaStatements.

  • Removed deprecated SchemaStatements#distinct.

  • Moved deprecated ActiveRecord::TestCase into the rails test suite. The class is no longer public and is only used for internal Rails tests.

  • Removed support for deprecated option :restrict for :dependent in associations.

  • Removed support for deprecated delete_sql in associations.

  • Removed support for deprecated insert_sql in associations.

  • Removed support for deprecated finder_sql in associations.

  • Removed support for deprecated counter_sql in associations.

  • Removed deprecated method type_cast_code from Column.

  • Removed deprecated options delete_sql and insert_sql from HABTM association.

  • Removed deprecated options finder_sql and counter_sql from collection association.

  • Removed deprecated ActiveRecord::Base#connection method. Make sure to access it via the class.

  • Removed deprecation warning for auto_explain_threshold_in_seconds.

  • Removed deprecated :distinct option from Relation#count.

  • Removed deprecated methods partial_updates, partial_updates? and partial_updates=.

  • Removed deprecated method scoped

  • Removed deprecated method default_scopes?

  • Remove implicit join references that were deprecated in 4.0.

  • Removed activerecord-deprecated_finders as a dependency

  • Usage of implicit_readonly is being removed. Please use readonly method explicitly to mark records as `readonly. (Pull Request)


  • Deprecated quoted_locking_column method, which isn't used anywhere.

  • Deprecated the delegation of Array bang methods for associations. To use them, instead first call #to_a on the association to access the array to be acted on. (Pull Request)

  • Deprecated ConnectionAdapters::SchemaStatements#distinct, as it is no longer used by internals. (Pull Request)

Notable changes

  • Added ActiveRecord::Base.to_param for convenient "pretty" URLs derived from a model's attribute or method. (Pull Request)

  • Added ActiveRecord::Base.no_touching, which allows ignoring touch on models. (Pull Request)

  • Unify boolean type casting for MysqlAdapter and Mysql2Adapter. type_cast will return 1 for true and 0 for false. (Pull Request)

  • .unscope now removes conditions specified in default_scope. (Commit)

  • Added ActiveRecord::QueryMethods#rewhere which will overwrite an existing, named where condition. (Commit)

  • Extended ActiveRecord::Base#cache_key to take an optional list of timestamp attributes of which the highest will be used. (Commit)

  • Added ActiveRecord::Base#enum for declaring enum attributes where the values map to integers in the database, but can be queried by name. (Commit)

  • Type cast json values on write, so that the value is consistent with reading from the database. (Pull Request)

  • Type cast hstore values on write, so that the value is consistent with reading from the database. (Commit)

  • Make next_migration_number accessible for third party generators. (Pull Request)

  • Calling update_attributes will now throw an ArgumentError whenever it gets a nil argument. More specifically, it will throw an error if the argument that it gets passed does not respond to to stringify_keys. (Pull Request)

  • CollectionAssociation#first/#last (e.g. has_many) use a LIMITed query to fetch results rather than loading the entire collection. (Pull Request)

  • inspect on Active Record model classes does not initiate a new connection. This means that calling inspect, when the database is missing, will no longer raise an exception. (Pull Request)

  • Removed column restrictions for count, let the database raise if the SQL is invalid. (Pull Request)

  • Rails now automatically detects inverse associations. If you do not set the :inverse_of option on the association, then Active Record will guess the inverse association based on heuristics. (Pull Request)

  • Handle aliased attributes in ActiveRecord::Relation. When using symbol keys, ActiveRecord will now translate aliased attribute names to the actual column name used in the database. (Pull Request)

  • The ERB in fixture files is no longer evaluated in the context of the main object. Helper methods used by multiple fixtures should be defined on modules included in ActiveRecord::FixtureSet.context_class. (Pull Request)


See the full list of contributors to Rails for the many people who spent many hours making Rails, the stable and robust framework it is. Kudos to all of them.

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