1 files changed, 71 insertions, 3 deletions
diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index b3e4505fc0..4b421633e2 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -54,10 +54,75 @@ NOTE: This section is a work in progress.
 
 ### Serialized attributes
 
-When assigning `nil` to a serialized attribute, it will be saved to the database
+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).
 
+### `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.
+
+In the next major Rails version `Rails Html Sanitizer` will be the default
+sanitizer. It already is for new applications.
+
+Include this in your Gemfile to try it out today:
+
+```ruby
+gem 'rails-html-sanitizer'
+```
+
+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.
+
 Upgrading from Rails 4.0 to Rails 4.1
 -------------------------------------
 
@@ -132,7 +197,7 @@ 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
@@ -532,7 +597,7 @@ 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
@@ -592,6 +657,9 @@ 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