Document that scopes require a callable object

1 files changed, 9 insertions, 1 deletions

diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index dc0bc5bea1..77a09cd5f0 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -47,8 +47,16 @@ Rails 4.0 no longer supports loading plugins from `vendor/plugins`. You must rep
 
 * 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) to a smoothly upgrade path.
 
-* Rails 4.0 has deprecated `ActiveRecord::Fixtures` in favor of `ActiveRecord::FixtureSet`.
+* Rails 4.0 requires that scopes use a callable object such as a Proc or lambda:
+
+```ruby
+  scope :active, where(active: true)
 
+  # becomes
+  scope :active, -> { where active: true }
+```
+
+* Rails 4.0 has deprecated `ActiveRecord::Fixtures` in favor of `ActiveRecord::FixtureSet`.
 * Rails 4.0 has deprecated `ActiveRecord::TestCase` in favor of `ActiveSupport::TestCase`.
 
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