Merge branch 'master' into activestorage-guide

21 files changed, 275 insertions, 59 deletions

diff --git a/guides/CHANGELOG.md b/guides/CHANGELOG.md
index d8b122d264..518b6abfb3 100644
--- a/guides/CHANGELOG.md
+++ b/guides/CHANGELOG.md
@@ -1 +1,10 @@
+## Rails 5.2.0.beta2 (November 28, 2017) ##
+
+*   No changes.
+
+
+## Rails 5.2.0.beta1 (November 27, 2017) ##
+
+*   No changes.
+
 Please check [5-1-stable](https://github.com/rails/rails/blob/5-1-stable/guides/CHANGELOG.md) for previous changes.
diff --git a/guides/assets/images/belongs_to.png b/guides/assets/images/belongs_to.png
index 1a9926e578..2b8c1d52ea 100644
--- a/guides/assets/images/belongs_to.png
+++ b/guides/assets/images/belongs_to.png
diff --git a/guides/assets/images/habtm.png b/guides/assets/images/habtm.png
index 41013b743d..7e508cc1a6 100644
--- a/guides/assets/images/habtm.png
+++ b/guides/assets/images/habtm.png
diff --git a/guides/assets/images/has_many.png b/guides/assets/images/has_many.png
index 0d67bea38b..36ccf9f0f6 100644
--- a/guides/assets/images/has_many.png
+++ b/guides/assets/images/has_many.png
diff --git a/guides/assets/images/has_many_through.png b/guides/assets/images/has_many_through.png
index b4da60e1fb..9e9caabd73 100644
--- a/guides/assets/images/has_many_through.png
+++ b/guides/assets/images/has_many_through.png
diff --git a/guides/assets/images/has_one.png b/guides/assets/images/has_one.png
index c70763856a..c29c6b9c59 100644
--- a/guides/assets/images/has_one.png
+++ b/guides/assets/images/has_one.png
diff --git a/guides/assets/images/has_one_through.png b/guides/assets/images/has_one_through.png
index 888a02b775..fdf13286c4 100644
--- a/guides/assets/images/has_one_through.png
+++ b/guides/assets/images/has_one_through.png
diff --git a/guides/assets/images/polymorphic.png b/guides/assets/images/polymorphic.png
index e0a7f6d64a..d630db9e01 100644
--- a/guides/assets/images/polymorphic.png
+++ b/guides/assets/images/polymorphic.png
diff --git a/guides/rails_guides/markdown/renderer.rb b/guides/rails_guides/markdown/renderer.rb
index 1f2fe91ea1..78820a7856 100644
--- a/guides/rails_guides/markdown/renderer.rb
+++ b/guides/rails_guides/markdown/renderer.rb
@@ -75,7 +75,7 @@ HTML
           #
           # It is important that we do not eat more than one newline
           # because formatting may be wrong otherwise. For example,
-          # if a bulleted list follows the first item is not rendered
+          # if a bulleted list follows, the first item is not rendered
           # as a list item, but as a paragraph starting with a plain
           # asterisk.
           body.gsub(/^(TIP|IMPORTANT|CAUTION|WARNING|NOTE|INFO|TODO)[.:](.*?)(\n(?=\n)|\Z)/m) do
diff --git a/guides/source/5_2_release_notes.md b/guides/source/5_2_release_notes.md
new file mode 100644
index 0000000000..eb361e200a
--- /dev/null
+++ b/guides/source/5_2_release_notes.md
@@ -0,0 +1,210 @@
+**DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON http://guides.rubyonrails.org.**
+
+Ruby on Rails 5.2 Release Notes
+===============================
+
+Highlights in Rails 5.2:
+
+* Active Storage
+* Redis Cache Store
+* HTTP/2 Early hints support
+* Credentials
+* Default Content Security Policy
+
+These release notes cover only the major changes. To learn 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/5-2-stable) in the main Rails
+repository on GitHub.
+
+--------------------------------------------------------------------------------
+
+Upgrading to Rails 5.2
+----------------------
+
+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 5.1 in case you
+haven't and make sure your application still runs as expected before attempting
+an update to Rails 5.2.
+
+
+Major Features
+--------------
+
+### Active Storage
+
+[README](https://github.com/rails/rails/blob/d3893ec38ec61282c2598b01a298124356d6b35a/activestorage/README.md)
+
+### Redis Cache Store
+
+[Pull Request](https://github.com/rails/rails/pull/31134)
+
+
+### HTTP/2 Early hints support
+
+[Pull Request](https://github.com/rails/rails/pull/30744)
+
+
+### Credentials
+
+[Pull Request](https://github.com/rails/rails/pull/30067)
+
+
+### Default Content Security Policy
+
+[Pull Request](https://github.com/rails/rails/pull/31162)
+
+Incompatibilities
+-----------------
+
+ToDo
+
+Railties
+--------
+
+Please refer to the [Changelog][railties] for detailed changes.
+
+### Removals
+
+ToDo
+
+### Notable changes
+
+ToDo
+
+Action Cable
+-----------
+
+Please refer to the [Changelog][action-cable] for detailed changes.
+
+### Notable changes
+
+ToDo
+
+Action Pack
+-----------
+
+Please refer to the [Changelog][action-pack] for detailed changes.
+
+### Removals
+
+ToDo
+
+### Deprecations
+
+ToDo
+
+### Notable changes
+
+ToDo
+
+Action View
+-------------
+
+Please refer to the [Changelog][action-view] for detailed changes.
+
+### Removals
+
+ToDo
+
+### Deprecations
+
+ToDo
+
+### Notable changes
+
+ToDo
+
+Action Mailer
+-------------
+
+Please refer to the [Changelog][action-mailer] for detailed changes.
+
+### Notable changes
+
+ToDo
+
+Active Record
+-------------
+
+Please refer to the [Changelog][active-record] for detailed changes.
+
+ToDo
+
+### Deprecations
+
+ToDo
+
+### Notable changes
+
+ToDo
+
+Active Model
+------------
+
+Please refer to the [Changelog][active-model] for detailed changes.
+
+### Removals
+
+ToDo
+
+### Notable changes
+
+ToDo
+
+Active Storage
+--------------
+
+Please refer to the [Changelog][active-support] for detailed changes.
+
+### Notable changes
+
+ToDo
+
+Active Support
+--------------
+
+Please refer to the [Changelog][active-support] for detailed changes.
+
+### Removals
+
+ToDo
+
+### Deprecations
+
+ToDo
+
+### Notable changes
+
+ToDo
+
+Active Job
+-----------
+
+Please refer to the [Changelog][active-job] for detailed changes.
+
+### Removals
+
+ToDo
+
+### Notable changes
+
+ToDo
+
+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.
+
+[railties]:       https://github.com/rails/rails/blob/5-2-stable/railties/CHANGELOG.md
+[action-pack]:    https://github.com/rails/rails/blob/5-2-stable/actionpack/CHANGELOG.md
+[action-view]:    https://github.com/rails/rails/blob/5-2-stable/actionview/CHANGELOG.md
+[action-mailer]:  https://github.com/rails/rails/blob/5-2-stable/actionmailer/CHANGELOG.md
+[action-cable]:   https://github.com/rails/rails/blob/5-2-stable/actioncable/CHANGELOG.md
+[active-record]:  https://github.com/rails/rails/blob/5-2-stable/activerecord/CHANGELOG.md
+[active-model]:   https://github.com/rails/rails/blob/5-2-stable/activemodel/CHANGELOG.md
+[active-storage]: https://github.com/rails/rails/blob/5-2-stable/activestorage/CHANGELOG.md
+[active-support]: https://github.com/rails/rails/blob/5-2-stable/activesupport/CHANGELOG.md
+[active-job]:     https://github.com/rails/rails/blob/5-2-stable/activejob/CHANGELOG.md
diff --git a/guides/source/action_cable_overview.md b/guides/source/action_cable_overview.md
index 57403a4bf9..1a86b1fcbb 100644
--- a/guides/source/action_cable_overview.md
+++ b/guides/source/action_cable_overview.md
@@ -1,12 +1,12 @@
 Action Cable Overview
 =====================
 
-In this guide you will learn how Action Cable works and how to use WebSockets to
+In this guide, you will learn how Action Cable works and how to use WebSockets to
 incorporate real-time features into your Rails application.
 
 After reading this guide, you will know:
 
-* What Action Cable is and its integration on backend and frontend
+* What Action Cable is and its integration backend and frontend
 * How to setup Action Cable
 * How to setup channels
 * Deployment and Architecture setup for running Action Cable
@@ -129,7 +129,7 @@ subscriptions based on an identifier sent by the cable consumer.
 # app/channels/chat_channel.rb
 class ChatChannel < ApplicationCable::Channel
   # Called when the consumer has successfully
-  # become a subscriber of this channel.
+  # become a subscriber to this channel.
   def subscribed
   end
 end
@@ -225,7 +225,7 @@ A *broadcasting* is a pub/sub link where anything transmitted by a publisher
 is routed directly to the channel subscribers who are streaming that named
 broadcasting. Each channel can be streaming zero or more broadcastings.
 
-Broadcastings are purely an online queue and time dependent. If a consumer is
+Broadcastings are purely an online queue and time-dependent. If a consumer is
 not streaming (subscribed to a given channel), they'll not get the broadcast
 should they connect later.
 
@@ -515,8 +515,8 @@ user. For a user with an ID of 1, the broadcasting name would be
 The channel has been instructed to stream everything that arrives at
 `web_notifications:1` directly to the client by invoking the `received`
 callback. The data passed as argument is the hash sent as the second parameter
-to the server-side broadcast call, JSON encoded for the trip across the wire,
-and unpacked for the data argument arriving to `received`.
+to the server-side broadcast call, JSON encoded for the trip across the wire
+and unpacked for the data argument arriving as `received`.
 
 ### More Complete Examples
 
@@ -569,7 +569,7 @@ This may change in the future. [#27214](https://github.com/rails/rails/issues/27
 
 Action Cable will only accept requests from specified origins, which are
 passed to the server config as an array. The origins can be instances of
-strings or regular expressions, against which a check for match will be performed.
+strings or regular expressions, against which a check for the match will be performed.
 
 ```ruby
 config.action_cable.allowed_request_origins = ['http://rubyonrails.com', %r{http://ruby.*}]
@@ -592,7 +592,7 @@ environment configuration files.
 
 ### Other Configurations
 
-The other common option to configure, is the log tags applied to the
+The other common option to configure is the log tags applied to the
 per-connection logger. Here's an example that uses
 the user account id if available, else "no-account" while tagging:
 
@@ -607,7 +607,7 @@ config.action_cable.log_tags = [
 For a full list of all configuration options, see the
 `ActionCable::Server::Configuration` class.
 
-Also note that your server must provide at least the same number of database
+Also, note that your server must provide at least the same number of database
 connections as you have workers. The default worker pool size is set to 4, so
 that means you have to make at least that available. You can change that in
 `config/database.yml` through the `pool` attribute.
diff --git a/guides/source/action_controller_overview.md b/guides/source/action_controller_overview.md
index 28f7246197..6ecfb57db3 100644
--- a/guides/source/action_controller_overview.md
+++ b/guides/source/action_controller_overview.md
@@ -21,7 +21,7 @@ After reading this guide, you will know:
 What Does a Controller Do?
 --------------------------
 
-Action Controller is the C in MVC. After the router has determined which controller to use for a request, the controller is responsible for making sense of the request and producing the appropriate output. Luckily, Action Controller does most of the groundwork for you and uses smart conventions to make this as straightforward as possible.
+Action Controller is the C in [MVC](https://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller). After the router has determined which controller to use for a request, the controller is responsible for making sense of the request, and producing the appropriate output. Luckily, Action Controller does most of the groundwork for you and uses smart conventions to make this as straightforward as possible.
 
 For most conventional [RESTful](https://en.wikipedia.org/wiki/Representational_state_transfer) applications, the controller will receive the request (this is invisible to you as the developer), fetch or save data from a model and use a view to create HTML output. If your controller needs to do things a little differently, that's not a problem, this is just the most common way for a controller to work.
 
diff --git a/guides/source/api_app.md b/guides/source/api_app.md
index 43a7de88b0..b360f270d7 100644
--- a/guides/source/api_app.md
+++ b/guides/source/api_app.md
@@ -414,8 +414,10 @@ Some common modules you might want to add:
 
 - `AbstractController::Translation`: Support for the `l` and `t` localization
   and translation methods.
-- `ActionController::HttpAuthentication::Basic` (or `Digest` or `Token`): Support
-  for basic, digest or token HTTP authentication.
+- Support for basic, digest or token HTTP authentication:
+  * `ActionController::HttpAuthentication::Basic::ControllerMethods`,
+  * `ActionController::HttpAuthentication::Digest::ControllerMethods`,
+  * `ActionController::HttpAuthentication::Token::ControllerMethods`
 - `ActionView::Layouts`: Support for layouts when rendering.
 - `ActionController::MimeResponds`: Support for `respond_to`.
 - `ActionController::Cookies`: Support for `cookies`, which includes
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 6e129a5680..4bfcc1e21a 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -578,6 +578,8 @@ Defaults to `'signed cookie'`.
 
 * `config.action_view.form_with_generates_remote_forms` determines whether `form_with` generates remote forms or not. This defaults to `true`.
 
+* `config.action_view.form_with_generates_ids` determines whether `form_with` generates ids on inputs. This defaults to `true`.
+
 ### Configuring Action Mailer
 
 There are a number of settings available on `config.action_mailer`:
diff --git a/guides/source/documents.yaml b/guides/source/documents.yaml
index 126d2e4845..2a4abab116 100644
--- a/guides/source/documents.yaml
+++ b/guides/source/documents.yaml
@@ -194,6 +194,10 @@
       url: upgrading_ruby_on_rails.html
       description: This guide helps in upgrading applications to latest Ruby on Rails versions.
     -
+      name: Ruby on Rails 5.2 Release Notes
+      url: 5_2_release_notes.html
+      description: Release notes for Rails 5.2.
+    -
       name: Ruby on Rails 5.1 Release Notes
       url: 5_1_release_notes.html
       description: Release notes for Rails 5.1.
diff --git a/guides/source/engines.md b/guides/source/engines.md
index b226eac347..33694cf76a 100644
--- a/guides/source/engines.md
+++ b/guides/source/engines.md
@@ -921,7 +921,7 @@ engine:
 mattr_accessor :author_class
 ```
 
-This method works like its brothers, `attr_accessor` and `cattr_accessor`, but
+This method works like its siblings, `attr_accessor` and `cattr_accessor`, but
 provides a setter and getter method on the module with the specified name. To
 use it, it must be referenced using `Blorgh.author_class`.
 
@@ -982,7 +982,7 @@ Blorgh.author_class = "User"
 WARNING: It's very important here to use the `String` version of the class,
 rather than the class itself. If you were to use the class, Rails would attempt
 to load that class and then reference the related table. This could lead to
-problems if the table wasn't already existing. Therefore, a `String` should be
+problems if the table didn't already exist. Therefore, a `String` should be
 used and then converted to a class using `constantize` in the engine later on.
 
 Go ahead and try to create a new article. You will see that it works exactly in the
@@ -1514,7 +1514,7 @@ To hook into the initialization process of one of the following classes use the
 
 ## Configuration hooks
 
-These are the available configuration hooks. They do not hook into any particular framework, instead they run in context of the entire application.
+These are the available configuration hooks. They do not hook into any particular framework, but instead they run in context of the entire application.
 
 | Hook                   | Use Case                                                                              |
 | ---------------------- | ------------------------------------------------------------------------------------- |
diff --git a/guides/source/layout.html.erb b/guides/source/layout.html.erb
index 334595e4d2..3981199e95 100644
--- a/guides/source/layout.html.erb
+++ b/guides/source/layout.html.erb
@@ -99,9 +99,9 @@
           To get started, you can read our <%= link_to 'documentation contributions', 'http://edgeguides.rubyonrails.org/contributing_to_ruby_on_rails.html#contributing-to-the-rails-documentation' %> section.
         </p>
         <p>
-          You may also find incomplete content, or stuff that is not up to date.
+          You may also find incomplete content or stuff that is not up to date.
           Please do add any missing documentation for master. Make sure to check
-          <%= link_to 'Edge Guides','http://edgeguides.rubyonrails.org' %> first to verify
+          <%= link_to 'Edge Guides', 'http://edgeguides.rubyonrails.org' %> first to verify
           if the issues are already fixed or not on the master branch.
           Check the <%= link_to 'Ruby on Rails Guides Guidelines', 'ruby_on_rails_guides_guidelines.html' %>
           for style and conventions.
@@ -111,7 +111,7 @@
           <%= link_to 'open an issue', 'https://github.com/rails/rails/issues' %>.
         </p>
         <p>And last but not least, any kind of discussion regarding Ruby on Rails
-          documentation is very welcome in the <%= link_to 'rubyonrails-docs mailing list', 'https://groups.google.com/forum/#!forum/rubyonrails-docs' %>.
+          documentation is very welcome on the <%= link_to 'rubyonrails-docs mailing list', 'https://groups.google.com/forum/#!forum/rubyonrails-docs' %>.
         </p>
       </div>
     </div>
diff --git a/guides/source/layouts_and_rendering.md b/guides/source/layouts_and_rendering.md
index f4597b0e60..4d79b2db89 100644
--- a/guides/source/layouts_and_rendering.md
+++ b/guides/source/layouts_and_rendering.md
@@ -285,7 +285,7 @@ the response. Using `:plain` or `:html` might be more appropriate most of the
 time.
 
 NOTE: Unless overridden, your response returned from this render option will be
-`text/html`, as that is the default content type of Action Dispatch response.
+`text/plain`, as that is the default content type of Action Dispatch response.
 
 #### Options for `render`
 
diff --git a/guides/source/rails_on_rack.md b/guides/source/rails_on_rack.md
index aa1476ecc0..5718b9ddfc 100644
--- a/guides/source/rails_on_rack.md
+++ b/guides/source/rails_on_rack.md
@@ -122,6 +122,7 @@ use ActiveRecord::Migration::CheckPending
 use ActionDispatch::Cookies
 use ActionDispatch::Session::CookieStore
 use ActionDispatch::Flash
+use ActionDispatch::ContentSecurityPolicy::Middleware
 use Rack::Head
 use Rack::ConditionalGet
 use Rack::ETag
@@ -249,7 +250,7 @@ Much of Action Controller's functionality is implemented as Middlewares. The fol
 
 **`Rails::Rack::Logger`**
 
-* Notifies the logs that the request has began. After request is complete, flushes all the logs.
+* Notifies the logs that the request has begun. After the request is complete, flushes all the logs.
 
 **`ActionDispatch::ShowExceptions`**
 
@@ -289,7 +290,7 @@ Much of Action Controller's functionality is implemented as Middlewares. The fol
 
 **`Rack::ConditionalGet`**
 
-* Adds support for "Conditional `GET`" so that server responds with nothing if page wasn't changed.
+* Adds support for "Conditional `GET`" so that server responds with nothing if the page wasn't changed.
 
 **`Rack::ETag`**
 
diff --git a/guides/source/security.md b/guides/source/security.md
index fa90cadcd2..eeb005b661 100644
--- a/guides/source/security.md
+++ b/guides/source/security.md
@@ -52,7 +52,7 @@ User.find(session[:user_id])
 
 NOTE: _The session ID is a 32-character random hex string._
 
-The session ID is generated using `SecureRandom.hex` which generates a random hex string using platform specific methods (such as OpenSSL, /dev/urandom or Win32) for generating cryptographically secure random numbers. Currently it is not feasible to brute-force Rails' session IDs.
+The session ID is generated using `SecureRandom.hex` which generates a random hex string using platform specific methods (such as OpenSSL, /dev/urandom or Win32 CryptoAPI) for generating cryptographically secure random numbers. Currently it is not feasible to brute-force Rails' session IDs.
 
 ### Session Hijacking
 
diff --git a/guides/source/working_with_javascript_in_rails.md b/guides/source/working_with_javascript_in_rails.md
index b2716c7faa..86746a5ae0 100644
--- a/guides/source/working_with_javascript_in_rails.md
+++ b/guides/source/working_with_javascript_in_rails.md
@@ -188,15 +188,20 @@ bind to the `ajax:success` event. On failure, use `ajax:error`. Check it out:
 
 ```coffeescript
 $(document).ready ->
-  $("#new_article").on("ajax:success", (e, data, status, xhr) ->
+  $("#new_article").on("ajax:success", (event) ->
+    [data, status, xhr] = event.detail
     $("#new_article").append xhr.responseText
-  ).on "ajax:error", (e, xhr, status, error) ->
+  ).on "ajax:error", (event) ->
     $("#new_article").append "<p>ERROR</p>"
 ```
 
 Obviously, you'll want to be a bit more sophisticated than that, but it's a
 start.
 
+NOTE: As of Rails 5.1 and the new `rails-ujs`, the parameters `data, status, xhr`
+have been bundled into `event.detail`. For information about the previously used
+`jquery-ujs` in Rails 5 and earlier, read the [`jquery-ujs` wiki](https://github.com/rails/jquery-ujs/wiki/ajax).
+
 #### link_to
 
 [`link_to`](http://api.rubyonrails.org/classes/ActionView/Helpers/UrlHelper.html#method-i-link_to)
@@ -225,7 +230,7 @@ and write some CoffeeScript like this:
 
 ```coffeescript
 $ ->
-  $("a[data-remote]").on "ajax:success", (e, data, status, xhr) ->
+  $("a[data-remote]").on "ajax:success", (event) ->
     alert "The article was deleted."
 ```
 
@@ -343,39 +348,6 @@ This generates a form with:
 <input data-disable-with="Saving..." type="submit">
 ```
 
-Dealing with Ajax events
-------------------------
-
-Here are the different events that are fired when you deal with elements
-that have a `data-remote` attribute:
-
-NOTE: All handlers bound to these events are always passed the event object as the
-first argument. The table below describes the extra parameters passed after the
-event argument. For example, if the extra parameters are listed as `xhr, settings`,
-then to access them, you would define your handler with `function(event, xhr, settings)`.
-
-| Event name          | Extra parameters | Fired                                                       |
-|---------------------|------------------|-------------------------------------------------------------|
-| `ajax:before`       |                  | Before the whole ajax business, aborts if stopped.          |
-| `ajax:beforeSend`   | xhr, options     | Before the request is sent, aborts if stopped.              |
-| `ajax:send`         | xhr              | When the request is sent.                                   |
-| `ajax:success`      | xhr, status, err | After completion, if the response was a success.            |
-| `ajax:error`        | xhr, status, err | After completion, if the response was an error.             |
-| `ajax:complete`     | xhr, status      | After the request has been completed, no matter the outcome.|
-| `ajax:aborted:file` | elements         | If there are non-blank file inputs, aborts if stopped.      |
-
-### Stoppable events
-
-If you stop `ajax:before` or `ajax:beforeSend` by returning false from the
-handler method, the Ajax request will never take place. The `ajax:before` event
-is also useful for manipulating form data before serialization. The
-`ajax:beforeSend` event is also useful for adding custom request headers.
-
-If you stop the `ajax:aborted:file` event, the default behavior of allowing the
-browser to submit the form via normal means (i.e. non-Ajax submission) will be
-canceled and the form will not be submitted at all. This is useful for
-implementing your own Ajax file upload workaround.
-
 ### Rails-ujs event handlers
 
 Rails 5.1 introduced rails-ujs and dropped jQuery as a dependency.
@@ -405,6 +377,22 @@ document.body.addEventListener('ajax:success', function(event) {
 })
 ```
 
+NOTE: As of Rails 5.1 and the new `rails-ujs`, the parameters `data, status, xhr`
+have been bundled into `event.detail`. For information about the previously used
+`jquery-ujs` in Rails 5 and earlier, read the [`jquery-ujs` wiki](https://github.com/rails/jquery-ujs/wiki/ajax).
+
+### Stoppable events
+
+If you stop `ajax:before` or `ajax:beforeSend` by returning false from the
+handler method, the Ajax request will never take place. The `ajax:before` event
+can manipulate form data before serialization and the
+`ajax:beforeSend` event is useful for adding custom request headers.
+
+If you stop the `ajax:aborted:file` event, the default behavior of allowing the
+browser to submit the form via normal means (i.e. non-Ajax submission) will be
+canceled and the form will not be submitted at all. This is useful for
+implementing your own Ajax file upload workaround.
+
 Server-Side Concerns
 --------------------