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diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 72a4bb4c2d..d7fbe575c2 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -1,12 +1,16 @@
+**DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON http://guides.rubyonrails.org.**
+
A Guide for Upgrading Ruby on Rails
===================================
This guide provides steps to be followed when you upgrade your applications to a newer version of Ruby on Rails. These steps are also available in individual release guides.
+--------------------------------------------------------------------------------
+
General Advice
--------------
-Before attempting to upgrade an existing application, you should be sure you have a good reason to upgrade. You need to balance out several factors: the need for new features, the increasing difficulty of finding support for old code, and your available time and skills, to name a few.
+Before attempting to upgrade an existing application, you should be sure you have a good reason to upgrade. You need to balance several factors: the need for new features, the increasing difficulty of finding support for old code, and your available time and skills, to name a few.
### Test Coverage
@@ -16,23 +20,271 @@ The best way to be sure that your application still works after upgrading is to
Rails generally stays close to the latest released Ruby version when it's released:
-* Rails 3 and above require Ruby 1.8.7 or higher. Support for all of the previous Ruby versions has been dropped officially. You should upgrade as early as possible.
-* Rails 3.2.x is the last branch to support Ruby 1.8.7.
+* Rails 5 requires Ruby 2.2 or newer.
* Rails 4 prefers Ruby 2.0 and requires 1.9.3 or newer.
+* Rails 3.2.x is the last branch to support Ruby 1.8.7.
+* Rails 3 and above require Ruby 1.8.7 or higher. Support for all of the previous Ruby versions has been dropped officially. You should upgrade as early as possible.
TIP: Ruby 1.8.7 p248 and p249 have marshaling bugs that crash Rails. Ruby Enterprise Edition has these fixed since the release of 1.8.7-2010.02. On the 1.9 front, Ruby 1.9.1 is not usable because it outright segfaults, so if you want to use 1.9.x, jump straight to 1.9.3 for smooth sailing.
-Upgrading from Rails 4.0 to Rails 4.1
+### The Rake Task
+
+Rails provides the `rails:update` rake task. After updating the Rails version
+in the Gemfile, run this rake task.
+This will help you with the creation of new files and changes of old files in an
+interactive session.
+
+```bash
+$ rake rails:update
+ identical config/boot.rb
+ exist config
+ conflict config/routes.rb
+Overwrite /myapp/config/routes.rb? (enter "h" for help) [Ynaqdh]
+ force config/routes.rb
+ conflict config/application.rb
+Overwrite /myapp/config/application.rb? (enter "h" for help) [Ynaqdh]
+ force config/application.rb
+ conflict config/environment.rb
+...
+```
+
+Don't forget to review the difference, to see if there were any unexpected changes.
+
+Upgrading from Rails 4.2 to Rails 5.0
+-------------------------------------
+
+### Halting callback chains by returning `false`
+
+In Rails 4.2, when a 'before' callback returns `false` in ActiveRecord,
+ActiveModel and ActiveModel::Validations, then the entire callback chain
+is halted. In other words, successive 'before' callbacks are not executed,
+and neither is the action wrapped in callbacks.
+
+In Rails 5.0, returning `false` in a callback will not have this side effect
+of halting the callback chain. Instead, callback chains must be explicitly
+halted by calling `throw(:abort)`.
+
+When you upgrade from Rails 4.2 to Rails 5.0, returning `false` in a callback
+will still halt the callback chain, but 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 the following configuration to your `config/application.rb`:
+
+ config.active_support.halt_callback_chains_on_return_false = false
+
+See [#17227](https://github.com/rails/rails/pull/17227) for more details.
+
+Upgrading from Rails 4.1 to Rails 4.2
-------------------------------------
-NOTE: This section is a work in progress.
+### Web Console
+
+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.
+
+### Responders
+
+`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:
+
+```ruby
+# 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:
+
+```ruby
+# 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](https://github.com/rails/rails/pull/16526) for more details.
+
+### Error handling in transaction callbacks
+
+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](https://github.com/rails/rails/pull/14488) and
+[#16537](https://github.com/rails/rails/pull/16537) for more details.
+
+### Ordering of test cases
+
+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:
+
+```ruby
+# config/environments/test.rb
+Rails.application.configure do
+ config.active_support.test_order = :sorted # or `:random` if you prefer
+end
+```
+
+### Serialized attributes
+
+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).
+
+### Production log level
+
+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`:
+
+```ruby
+# Set to `:info` to match the current default, or set to `:debug` to opt-into
+# the future default.
+config.log_level = :info
+```
+
+### `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:
+
+```ruby
+# 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.
+
+```ruby
+# 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
+```
+
+### Rails HTML Sanitizer
+
+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`](https://github.com/rails/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](https://github.com/flavorjones/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](https://github.com/flavorjones/loofah#loofahscrubber).
+
+Two new scrubbers have also been added: `PermitScrubber` and `TargetScrubber`.
+Read the [gem's readme](https://github.com/rails/rails-html-sanitizer) 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:
+
+```ruby
+gem 'rails-deprecated_sanitizer'
+```
+
+### Rails DOM Testing
+
+The [`TagAssertions` module](http://api.rubyonrails.org/classes/ActionDispatch/Assertions/TagAssertions.html) (containing methods such as `assert_tag`), [has been deprecated](https://github.com/rails/rails/blob/6061472b8c310158a2a2e8e9a6b81a1aef6b60fe/actionpack/lib/action_dispatch/testing/assertions/dom.rb) in favor of the `assert_select` methods from the `SelectorAssertions` module, which has been extracted into the [rails-dom-testing gem](https://github.com/rails/rails-dom-testing).
+
+
+### Masked Authenticity Tokens
+
+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.
+
+### Action Mailer
+
+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:
+
+```ruby
+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:
+
+```ruby
+class Notifier < ActionMailer::Base
+ def self.broadcast_notifications(users, ...)
+ users.each { |user| Notifier.notify(user, ...) }
+ end
+end
+```
+
+Upgrading from Rails 4.0 to Rails 4.1
+-------------------------------------
### CSRF protection from remote `<script>` tags
Or, "whaaat my tests are failing!!!?"
Cross-site request forgery (CSRF) protection now covers GET requests with
-JavaScript responses, too. That prevents a third-party site from referencing
+JavaScript responses, too. This prevents a third-party site from referencing
your JavaScript URL and attempting to run it to extract sensitive data.
This means that your functional and integration tests that use
@@ -47,7 +299,7 @@ will now trigger CSRF protection. Switch to
xhr :get, :index, format: :js
```
-to explicitly test an XmlHttpRequest.
+to explicitly test an `XmlHttpRequest`.
If you really mean to load JavaScript from remote `<script>` tags, skip CSRF
protection on that action.
@@ -62,7 +314,7 @@ If you want to use Spring as your application preloader you need to:
NOTE: User defined rake tasks will run in the `development` environment by
default. If you want them to run in other environments consult the
-[Spring README](https://github.com/jonleighton/spring#rake).
+[Spring README](https://github.com/rails/spring#rake).
### `config/secrets.yml`
@@ -79,11 +331,14 @@ secrets, you need to:
secret_key_base:
production:
- secret_key_base:
+ secret_key_base: <%= ENV["SECRET_KEY_BASE"] %>
```
-2. Copy the existing `secret_key_base` from the `secret_token.rb` initializer to
- `secrets.yml` under the `production` section.
+2. Use your existing `secret_key_base` from the `secret_token.rb` initializer to
+ set the SECRET_KEY_BASE environment variable for whichever users running the
+ Rails application in production mode. Alternatively, you can simply copy the existing
+ `secret_key_base` from the `secret_token.rb` initializer to `secrets.yml`
+ under the `production` section, replacing '<%= ENV["SECRET_KEY_BASE"] %>'.
3. Remove the `secret_token.rb` initializer.
@@ -95,9 +350,66 @@ secrets, you need to:
If your test helper contains a call to
`ActiveRecord::Migration.check_pending!` this can be removed. The check
-is now done automatically when you `require 'test_help'`, although
+is now done automatically when you `require 'rails/test_help'`, although
leaving this line in your helper is not harmful in any way.
+### Cookies serializer
+
+Applications created before Rails 4.1 uses `Marshal` to serialize cookie values into
+the signed and encrypted cookie jars. If you want to use the new `JSON`-based format
+in your application, you can add an initializer file with the following content:
+
+```ruby
+Rails.application.config.action_dispatch.cookies_serializer = :hybrid
+```
+
+This would transparently migrate your existing `Marshal`-serialized cookies into the
+new `JSON`-based format.
+
+When using the `:json` or `:hybrid` serializer, you should beware that not all
+Ruby objects can be serialized as JSON. For example, `Date` and `Time` objects
+will be serialized as strings, and `Hash`es will have their keys stringified.
+
+```ruby
+class CookiesController < ApplicationController
+ def set_cookie
+ cookies.encrypted[:expiration_date] = Date.tomorrow # => Thu, 20 Mar 2014
+ redirect_to action: 'read_cookie'
+ end
+
+ def read_cookie
+ cookies.encrypted[:expiration_date] # => "2014-03-20"
+ end
+end
+```
+
+It's advisable that you only store simple data (strings and numbers) in cookies.
+If you have to store complex objects, you would need to handle the conversion
+manually when reading the values on subsequent requests.
+
+If you use the cookie session store, this would apply to the `session` and
+`flash` hash as well.
+
+### Flash structure changes
+
+Flash message keys are
+[normalized to strings](https://github.com/rails/rails/commit/a668beffd64106a1e1fedb71cc25eaaa11baf0c1). They
+can still be accessed using either symbols or strings. Looping through the flash
+will always yield string keys:
+
+```ruby
+flash["string"] = "a string"
+flash[:symbol] = "a symbol"
+
+# Rails < 4.1
+flash.keys # => ["string", :symbol]
+
+# Rails >= 4.1
+flash.keys # => ["string", "symbol"]
+```
+
+Make sure you are comparing Flash message keys against strings.
+
### Changes in JSON handling
There are a few major changes related to JSON handling in Rails 4.1.
@@ -130,7 +442,7 @@ Rails-specific features. For example:
```ruby
class FooBar
def as_json(options = nil)
- { foo: "bar" }
+ { foo: 'bar' }
end
end
@@ -148,10 +460,20 @@ part of the rewrite, the following features have been removed from the encoder:
2. Support for the `encode_json` hook
3. Option to encode `BigDecimal` objects as numbers instead of strings
-If you application depends on one of these features, you can get them back by
+If your application depends on one of these features, you can get them back by
adding the [`activesupport-json_encoder`](https://github.com/rails/activesupport-json_encoder)
gem to your Gemfile.
+#### JSON representation of Time objects
+
+`#as_json` for objects with time component (`Time`, `DateTime`, `ActiveSupport::TimeWithZone`)
+now returns millisecond precision by default. If you need to keep old behavior with no millisecond
+precision, set the following in an initializer:
+
+```
+ActiveSupport::JSON::Encoding.time_precision = 0
+```
+
### Usage of `return` within inline callback blocks
Previously, Rails allowed inline callback blocks to use `return` this way:
@@ -162,7 +484,7 @@ class ReadOnlyModel < ActiveRecord::Base
end
```
-This behaviour was never intentionally supported. Due to a change in the internals
+This behavior was never intentionally supported. Due to a change in the internals
of `ActiveSupport::Callbacks`, this is no longer allowed in Rails 4.1. Using a
`return` statement in an inline callback block causes a `LocalJumpError` to
be raised when the callback is executed.
@@ -207,7 +529,7 @@ included in the newly introduced `ActiveRecord::FixtureSet.context_class`, in
`test_helper.rb`.
```ruby
-class FixtureFileHelpers
+module FixtureFileHelpers
def file_sha(path)
Digest::SHA2.hexdigest(File.read(Rails.root.join('test/fixtures', path)))
end
@@ -217,8 +539,8 @@ ActiveRecord::FixtureSet.context_class.send :include, FixtureFileHelpers
### I18n enforcing available locales
-Rails 4.1 now defaults the I18n option `enforce_available_locales` to `true`,
-meaning that it will make sure that all locales passed to it must be declared in
+Rails 4.1 now defaults the I18n option `enforce_available_locales` to `true`. This
+means that it will make sure that all locales passed to it must be declared in
the `available_locales` list.
To disable it (and allow I18n to accept *any* locale option) add the following
@@ -228,9 +550,10 @@ configuration to your application:
config.i18n.enforce_available_locales = false
```
-Note that this option was added as a security measure, to ensure user input could
-not be used as locale information unless previously known, so it's recommended not
-to disable this option unless you have a strong reason for doing so.
+Note that this option was added as a security measure, to ensure user input
+cannot be used as locale information unless it is previously known. Therefore,
+it's recommended not to disable this option unless you have a strong reason for
+doing so.
### Mutator methods called on Relation
@@ -249,6 +572,114 @@ authors = Author.where(name: 'Hank Moody').to_a
authors.compact!
```
+### Changes on Default Scopes
+
+Default scopes are no longer overridden by chained conditions.
+
+In previous versions when you defined a `default_scope` in a model
+it was overridden by chained conditions in the same field. Now it
+is merged like any other scope.
+
+Before:
+
+```ruby
+class User < ActiveRecord::Base
+ default_scope { where state: 'pending' }
+ scope :active, -> { where state: 'active' }
+ scope :inactive, -> { where state: 'inactive' }
+end
+
+User.all
+# SELECT "users".* FROM "users" WHERE "users"."state" = 'pending'
+
+User.active
+# SELECT "users".* FROM "users" WHERE "users"."state" = 'active'
+
+User.where(state: 'inactive')
+# SELECT "users".* FROM "users" WHERE "users"."state" = 'inactive'
+```
+
+After:
+
+```ruby
+class User < ActiveRecord::Base
+ default_scope { where state: 'pending' }
+ scope :active, -> { where state: 'active' }
+ scope :inactive, -> { where state: 'inactive' }
+end
+
+User.all
+# SELECT "users".* FROM "users" WHERE "users"."state" = 'pending'
+
+User.active
+# SELECT "users".* FROM "users" WHERE "users"."state" = 'pending' AND "users"."state" = 'active'
+
+User.where(state: 'inactive')
+# SELECT "users".* FROM "users" WHERE "users"."state" = 'pending' AND "users"."state" = 'inactive'
+```
+
+To get the previous behavior it is needed to explicitly remove the
+`default_scope` condition using `unscoped`, `unscope`, `rewhere` or
+`except`.
+
+```ruby
+class User < ActiveRecord::Base
+ default_scope { where state: 'pending' }
+ scope :active, -> { unscope(where: :state).where(state: 'active') }
+ scope :inactive, -> { rewhere state: 'inactive' }
+end
+
+User.all
+# SELECT "users".* FROM "users" WHERE "users"."state" = 'pending'
+
+User.active
+# SELECT "users".* FROM "users" WHERE "users"."state" = 'active'
+
+User.inactive
+# SELECT "users".* FROM "users" WHERE "users"."state" = 'inactive'
+```
+
+### Rendering content from string
+
+Rails 4.1 introduces `:plain`, `:html`, and `:body` options to `render`. Those
+options are now the preferred way to render string-based content, as it allows
+you to specify which content type you want the response sent as.
+
+* `render :plain` will set the content type to `text/plain`
+* `render :html` will set the content type to `text/html`
+* `render :body` will *not* set the content type header.
+
+From the security standpoint, if you don't expect to have any markup in your
+response body, you should be using `render :plain` as most browsers will escape
+unsafe content in the response for you.
+
+We will be deprecating the use of `render :text` in a future version. So please
+start using the more precise `:plain`, `:html`, and `:body` options instead.
+Using `render :text` may pose a security risk, as the content is sent as
+`text/html`.
+
+### PostgreSQL json and hstore datatypes
+
+Rails 4.1 will map `json` and `hstore` columns to a string-keyed Ruby `Hash`.
+In earlier versions, a `HashWithIndifferentAccess` was used. This means that
+symbol access is no longer supported. This is also the case for
+`store_accessors` based on top of `json` or `hstore` columns. Make sure to use
+string keys consistently.
+
+### Explicit block use for `ActiveSupport::Callbacks`
+
+Rails 4.1 now expects an explicit block to be passed when calling
+`ActiveSupport::Callbacks.set_callback`. This change stems from
+`ActiveSupport::Callbacks` being largely rewritten for the 4.1 release.
+
+```ruby
+# Previously in Rails 4.0
+set_callback :save, :around, ->(r, &block) { stuff; result = block.call; stuff }
+
+# Now in Rails 4.1
+set_callback :save, :around, ->(r, block) { stuff; result = block.call; stuff }
+```
+
Upgrading from Rails 3.2 to Rails 4.0
-------------------------------------
@@ -320,7 +751,7 @@ being used, you can update your form to use the `PUT` method instead:
<%= form_for [ :update_name, @user ], method: :put do |f| %>
```
-For more on PATCH and why this change was made, see [this post](http://weblog.rubyonrails.org/2012/2/25/edge-rails-patch-is-the-new-primary-http-method-for-updates/)
+For more on PATCH and why this change was made, see [this post](http://weblog.rubyonrails.org/2012/2/26/edge-rails-patch-is-the-new-primary-http-method-for-updates/)
on the Rails blog.
#### A note about media types
@@ -336,7 +767,7 @@ def update
respond_to do |format|
format.json do
# perform a partial update
- @post.update params[:post]
+ @article.update params[:article]
end
format.json_patch do
@@ -363,7 +794,7 @@ file (in `config/application.rb`):
```ruby
# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
-Bundler.require(:default, Rails.env)
+Bundler.require(*Rails.groups)
```
### vendor/plugins
@@ -380,6 +811,9 @@ Rails 4.0 no longer supports loading plugins from `vendor/plugins`. You must rep
* Rails 4.0 has changed `serialized_attributes` and `attr_readonly` to class methods only. You shouldn't use instance methods since it's now deprecated. You should change them to use class methods, e.g. `self.serialized_attributes` to `self.class.serialized_attributes`.
+* When using the default coder, assigning `nil` to a serialized attribute will save it
+to the database as `NULL` instead of passing the `nil` value through YAML (`"--- \n...\n"`).
+
* Rails 4.0 has removed `attr_accessible` and `attr_protected` feature in favor of Strong Parameters. You can use the [Protected Attributes gem](https://github.com/rails/protected_attributes) for a smooth upgrade path.
* If you are not using Protected Attributes, you can remove any options related to
@@ -399,7 +833,7 @@ this gem such as `whitelist_attributes` or `mass_assignment_sanitizer` options.
* Rails 4.0 has deprecated `ActiveRecord::TestCase` in favor of `ActiveSupport::TestCase`.
* Rails 4.0 has deprecated the old-style hash based finder API. This means that
- methods which previously accepted "finder options" no longer do.
+ methods which previously accepted "finder options" no longer do. For example, `Book.find(:all, conditions: { name: '1984' })` has been deprecated in favor of `Book.where(name: '1984')`
* All dynamic methods except for `find_by_...` and `find_by_...!` are deprecated.
Here's how you can handle the changes:
@@ -424,7 +858,7 @@ Rails 4.0 extracted Active Resource to its own gem. If you still need the featur
* Rails 4.0 has changed how errors attach with the `ActiveModel::Validations::ConfirmationValidator`. Now when confirmation validations fail, the error will be attached to `:#{attribute}_confirmation` instead of `attribute`.
-* Rails 4.0 has changed `ActiveModel::Serializers::JSON.include_root_in_json` default value to `false`. Now, Active Model Serializers and Active Record objects have the same default behaviour. This means that you can comment or remove the following option in the `config/initializers/wrap_parameters.rb` file:
+* Rails 4.0 has changed `ActiveModel::Serializers::JSON.include_root_in_json` default value to `false`. Now, Active Model Serializers and Active Record objects have the same default behavior. This means that you can comment or remove the following option in the `config/initializers/wrap_parameters.rb` file:
```ruby
# Disable root element in JSON by default.
@@ -503,13 +937,13 @@ get 'こんにちは', controller: 'welcome', action: 'index'
```ruby
# Rails 3.x
- match "/" => "root#index"
+ match '/' => 'root#index'
# becomes
- match "/" => "root#index", via: :get
+ match '/' => 'root#index', via: :get
# or
- get "/" => "root#index"
+ get '/' => 'root#index'
```
* Rails 4.0 has removed `ActionDispatch::BestStandardsSupport` middleware, `<!DOCTYPE html>` already triggers standards mode per http://msdn.microsoft.com/en-us/library/jj676915(v=vs.85).aspx and ChromeFrame header has been moved to `config.action_dispatch.default_headers`.
@@ -550,13 +984,12 @@ The order in which helpers from more than one directory are loaded has changed i
### Active Record Observer and Action Controller Sweeper
-Active Record Observer and Action Controller Sweeper have been extracted to the `rails-observers` gem. You will need to add the `rails-observers` gem if you require these features.
+`ActiveRecord::Observer` and `ActionController::Caching::Sweeper` have been extracted to the `rails-observers` gem. You will need to add the `rails-observers` gem if you require these features.
### sprockets-rails
-* `assets:precompile:primary` has been removed. Use `assets:precompile` instead.
-* The `config.assets.compress` option should be changed to
-`config.assets.js_compressor` like so for instance:
+* `assets:precompile:primary` and `assets:precompile:all` have been removed. Use `assets:precompile` instead.
+* The `config.assets.compress` option should be changed to `config.assets.js_compressor` like so for instance:
```ruby
config.assets.js_compressor = :uglifier
@@ -564,22 +997,23 @@ config.assets.js_compressor = :uglifier
### sass-rails
-* `asset-url` with two arguments is deprecated. For example: `asset-url("rails.png", image)` becomes `asset-url("rails.png")`
+* `asset-url` with two arguments is deprecated. For example: `asset-url("rails.png", image)` becomes `asset-url("rails.png")`.
Upgrading from Rails 3.1 to Rails 3.2
-------------------------------------
-If your application is currently on any version of Rails older than 3.1.x, you should upgrade to Rails 3.1 before attempting an update to Rails 3.2.
+If your application is currently on any version of Rails older than 3.1.x, you
+should upgrade to Rails 3.1 before attempting an update to Rails 3.2.
-The following changes are meant for upgrading your application to Rails 3.2.16,
-the last 3.2.x version of Rails.
+The following changes are meant for upgrading your application to the latest
+3.2.x version of Rails.
### Gemfile
Make the following changes to your `Gemfile`.
```ruby
-gem 'rails', '3.2.16'
+gem 'rails', '3.2.21'
group :assets do
gem 'sass-rails', '~> 3.2.6'
@@ -704,8 +1138,8 @@ You can help test performance with these additions to your test environment:
```ruby
# Configure static asset server for tests with Cache-Control for performance
-config.serve_static_assets = true
-config.static_cache_control = "public, max-age=3600"
+config.serve_static_files = true
+config.static_cache_control = 'public, max-age=3600'
```
### config/initializers/wrap_parameters.rb
@@ -740,7 +1174,7 @@ AppName::Application.config.session_store :cookie_store, key: 'SOMETHINGNEW'
or
```bash
-$ rake db:sessions:clear
+$ bin/rake db:sessions:clear
```
### Remove :cache and :concat options in asset helpers references in views