1 files changed, 17 insertions, 1 deletions
diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index d7fbe575c2..20b90bdba0 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -276,6 +276,22 @@ class Notifier < ActionMailer::Base
 end
 ```
 
+### Foreign Key Support
+
+The migration DSL has been expanded to support foreign key definitions. If
+you've been using the Foreigner gem, you might want to consider removing it.
+Note that the foreign key support of Rails is a subset of Foreigner. This means
+that not every Foreigner definition can be fully replaced by it's Rails
+migration DSL counterpart.
+
+The migration procedure is as follows:
+
+1. remove `gem "foreigner"` from the Gemfile.
+2. run `bundle install`.
+3. run `bin/rake db:schema:dump`.
+4. make sure that `db/schema.rb` contains every foreign key definition with
+the necessary options.
+
 Upgrading from Rails 4.0 to Rails 4.1
 -------------------------------------
 
@@ -534,7 +550,7 @@ module FixtureFileHelpers
     Digest::SHA2.hexdigest(File.read(Rails.root.join('test/fixtures', path)))
   end
 end
-ActiveRecord::FixtureSet.context_class.send :include, FixtureFileHelpers
+ActiveRecord::FixtureSet.context_class.include FixtureFileHelpers
 ```
 
 ### I18n enforcing available locales