4_1_release_notes.md

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](https://github.com/rails/rails/commits/master) 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](upgrading_ruby_on_rails.html#upgrading-from-rails-4-0-to-rails-4-1)
guide.


Major Features
--------------

### Variants

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

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

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

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

  Provide separate templates for each format and variant:

  ```
    app/views/projects/show.html.erb
    app/views/projects/show.html+tablet.erb
    app/views/projects/show.html+phone.erb
  ```

Documentation
-------------


Railties
--------

Please refer to the
[Changelog](https://github.com/rails/rails/blob/4-1-stable/railties/CHANGELOG.md)
for detailed changes.

### Removals

* 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](https://github.com/rails/rails/commit/84eac5dab8b0fe9ee20b51250e52ad7bfea36553))

* Exposed `MiddlewareStack#unshift` to environment configuration. ([Pull Request](https://github.com/rails/rails/pull/12479))


Action Mailer
-------------

Please refer to the
[Changelog](https://github.com/rails/rails/blob/4-1-stable/actionmailer/CHANGELOG.md)
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](https://github.com/rails/rails/pull/12556))


Active Model
------------

Please refer to the
[Changelog](https://github.com/rails/rails/blob/4-1-stable/activemodel/CHANGELOG.md)
for detailed changes.

### Deprecations

* Deprecate `Validator#setup`. This should be done manually now in the
  validator's constructor. ([Commit](https://github.com/rails/rails/commit/7d84c3a2f7ede0e8d04540e9c0640de7378e9b3a))

### 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](https://github.com/rails/rails/blob/4-1-stable/activesupport/CHANGELOG.md)
for detailed changes.


### Removals

* Removed `MultiJSON` dependency. As a result, `ActiveSupport::JSON.decode`
  no longer accepts an options hash for `MultiJSON`. ([Pull Request](https://github.com/rails/rails/pull/10576) / [More Details](upgrading_ruby_on_rails.html#changes-in-json-handling))

* Removed support for the `encode_json` hook used for encoding custom objects into
  JSON. This feature has been extracted into the [activesupport-json_encoder](https://github.com/rails/activesupport-json_encoder)
  gem.
  ([Related Pull Request](https://github.com/rails/rails/pull/12183) /
  [More Details](upgrading_ruby_on_rails.html#changes-in-json-handling))

* Removed deprecated `ActiveSupport::JSON::Variable` with no replacement.

* 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.

### Deprecations

* 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](https://github.com/rails/rails/pull/12389))

* Deprecated the require path `active_support/core_ext/object/to_json`. Require
  `active_support/core_ext/object/json` instead. ([Pull Request](https://github.com/rails/rails/pull/12203))

* Deprecated `ActiveSupport::JSON::Encoding::CircularReferenceError`. This feature
  has been extracted into the [activesupport-json_encoder](https://github.com/rails/activesupport-json_encoder)
  gem.
  ([Pull Request](https://github.com/rails/rails/pull/12785) /
  [More Details](upgrading_ruby_on_rails.html#changes-in-json-handling))

* Deprecated `ActiveSupport.encode_big_decimal_as_string` option. This feature has
  been extracetd into the [activesupport-json_encoder](https://github.com/rails/activesupport-json_encoder)
  gem.
  ([Pull Request](https://github.com/rails/rails/pull/13060) /
  [More Details](upgrading_ruby_on_rails.html#changes-in-json-handling))

### Notable changes

* `ActiveSupport`'s JSON encoder has been rewritten to take advantage of the
  JSON gem rather than doing custom encoding in pure-Ruby.
  ([Pull Request](https://github.com/rails/rails/pull/12183) /
  [More Details](upgrading_ruby_on_rails.html#changes-in-json-handling))

* Improved compatibility with the JSON gem.
  ([Pull Request](https://github.com/rails/rails/pull/12862) /
  [More Details](upgrading_ruby_on_rails.html#changes-in-json-handling))

* Added `ActiveSupport::Testing::TimeHelpers#travel` and `#travel_to`. These
  methods change current time to the given time or time difference by stubbing
  `Time.now` and
  `Date.today`. ([Pull Request](https://github.com/rails/rails/pull/12824))

* Added `Numeric#in_milliseconds`, like `1.hour.in_milliseconds`, so we can feed
  them to JavaScript functions like
  `getTime()`. ([Commit](https://github.com/rails/rails/commit/423249504a2b468d7a273cbe6accf4f21cb0e643))

* 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](https://github.com/rails/rails/pull/10879))

* Added `String#remove(pattern)` as a short-hand for the common pattern of
  `String#gsub(pattern,'')`. ([Commit](https://github.com/rails/rails/commit/5da23a3f921f0a4a3139495d2779ab0d3bd4cb5f))

* Removed 'cow' => 'kine' irregular inflection from default
  inflections. ([Commit](https://github.com/rails/rails/commit/c300dca9963bda78b8f358dbcb59cabcdc5e1dc9))

Action Pack
-----------

Please refer to the
[Changelog](https://github.com/rails/rails/blob/4-1-stable/actionpack/CHANGELOG.md)
for detailed changes.

### Removals

* 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

* `#url_for` takes a hash with options inside an
  array. ([Pull Request](https://github.com/rails/rails/pull/9599))

* Added `session#fetch` method fetch behaves similarly to
  [Hash#fetch](http://www.ruby-doc.org/core-1.9.3/Hash.html#method-i-fetch),
  with the exception that the returned value is always saved into the
  session. ([Pull Request](https://github.com/rails/rails/pull/12692))

* Separated Action View completely from Action
  Pack. ([Pull Request](https://github.com/rails/rails/pull/11032))


Active Record
-------------

Please refer to the
[Changelog](https://github.com/rails/rails/blob/4-1-stable/activerecord/CHANGELOG.md)
for detailed changes.

### Removals

* 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`, `:insert_sql`, `:finder_sql`
  and `:counter_sql` options in associations.

* Removed deprecated method `type_cast_code` from Column.

* 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

* Removed usage of `implicit_readonly`. Please use `readonly` method
  explicitly to mark records as
  `readonly`. ([Pull Request](https://github.com/rails/rails/pull/10769))

### Deprecations

* 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](https://github.com/rails/rails/pull/12129))

* Deprecated `ConnectionAdapters::SchemaStatements#distinct`,
  as it is no longer used by internals. ([Pull Request](https://github.com/rails/rails/pull/10556))

### Notable changes

* Added `ActiveRecord::Base.to_param` for convenient "pretty" URLs derived from
  a model's attribute or
  method. ([Pull Request](https://github.com/rails/rails/pull/12891))

* Added `ActiveRecord::Base.no_touching`, which allows ignoring touch on
  models. ([Pull Request](https://github.com/rails/rails/pull/12772))

* Unify boolean type casting for `MysqlAdapter` and `Mysql2Adapter`.
  `type_cast` will return `1` for `true` and `0` for `false`. ([Pull Request](https://github.com/rails/rails/pull/12425))

* `.unscope` now removes conditions specified in
  `default_scope`. ([Commit](https://github.com/rails/rails/commit/94924dc32baf78f13e289172534c2e71c9c8cade))

* Added `ActiveRecord::QueryMethods#rewhere` which will overwrite an existing,
  named where condition. ([Commit](https://github.com/rails/rails/commit/f950b2699f97749ef706c6939a84dfc85f0b05f2))

* Extended `ActiveRecord::Base#cache_key` to take an optional list of timestamp
  attributes of which the highest will be used. ([Commit](https://github.com/rails/rails/commit/e94e97ca796c0759d8fcb8f946a3bbc60252d329))

* Added `ActiveRecord::Base#enum` for declaring enum attributes where the values
  map to integers in the database, but can be queried by
  name. ([Commit](https://github.com/rails/rails/commit/db41eb8a6ea88b854bf5cd11070ea4245e1639c5))

* Type cast json values on write, so that the value is consistent with reading
  from the database. ([Pull Request](https://github.com/rails/rails/pull/12643))

* Type cast hstore values on write, so that the value is consistent
  with reading from the database. ([Commit](https://github.com/rails/rails/commit/5ac2341fab689344991b2a4817bd2bc8b3edac9d))

* Make `next_migration_number` accessible for third party
  generators. ([Pull Request](https://github.com/rails/rails/pull/12407))

* 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](https://github.com/rails/rails/pull/9860))

* `CollectionAssociation#first`/`#last` (e.g. `has_many`) use a `LIMIT`ed
  query to fetch results rather than loading the entire
  collection. ([Pull Request](https://github.com/rails/rails/pull/12137))

* `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](https://github.com/rails/rails/pull/11014))

* Removed column restrictions for `count`, let the database raise if the SQL is
  invalid. ([Pull Request](https://github.com/rails/rails/pull/10710))

* 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](https://github.com/rails/rails/pull/10886))

* 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](https://github.com/rails/rails/pull/7839))

* 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](https://github.com/rails/rails/pull/13022))

Credits
-------

See the
[full list of contributors to Rails](http://contributors.rubyonrails.org/) for
the many people who spent many hours making Rails, the stable and robust
framework it is. Kudos to all of them.