Merge pull request #18363 from andreynering/add-foreign-key-subsection-in-upgrading-guide

Adding subsection on 'Upgrading' guide about foreign key support

[ci skip]

1 files changed, 16 insertions, 0 deletions

diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 909a92b9dd..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
 -------------------------------------