7 files changed, 47 insertions, 6 deletions
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index 14c2ddd85b..a1459c87c6 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -383,7 +383,7 @@ module ActiveRecord
       end
 
       def construct_relation_for_exists(relation, conditions)
-        relation = relation.except(:select, :distinct)._select!(ONE_AS_ONE).limit!(1)
+        relation = relation.except(:select, :distinct, :order)._select!(ONE_AS_ONE).limit!(1)
 
         case conditions
         when Array, Hash
diff --git a/activerecord/test/cases/finder_test.rb b/activerecord/test/cases/finder_test.rb
index 4fa664697c..a7b6333010 100644
--- a/activerecord/test/cases/finder_test.rb
+++ b/activerecord/test/cases/finder_test.rb
@@ -208,6 +208,11 @@ class FinderTest < ActiveRecord::TestCase
     assert_equal true, Topic.order(:id).distinct.exists?
   end
 
+  # Ensure +exists?+ runs without an error by excluding order value.
+  def test_exists_with_order
+    assert_equal true, Topic.order("invalid sql here").exists?
+  end
+
   def test_exists_with_joins
     assert_equal true, Topic.joins(:replies).where(replies_topics: { approved: true }).order("replies_topics.created_at DESC").exists?
   end
diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 6f99155199..1adc473e1d 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1 +1,7 @@
+*   Add `fetch_values` for `HashWithIndifferentAccess`
+
+    The method was originally added to `Hash` in Ruby 2.3.0.
+
+    *Josh Pencheon*
+
 Please check [5-1-stable](https://github.com/rails/rails/blob/5-1-stable/activesupport/CHANGELOG.md) for previous changes.
diff --git a/activesupport/lib/active_support/hash_with_indifferent_access.rb b/activesupport/lib/active_support/hash_with_indifferent_access.rb
index 1e1d6d3aac..3b185dd86b 100644
--- a/activesupport/lib/active_support/hash_with_indifferent_access.rb
+++ b/activesupport/lib/active_support/hash_with_indifferent_access.rb
@@ -195,6 +195,19 @@ module ActiveSupport
       indices.collect { |key| self[convert_key(key)] }
     end
 
+    # Returns an array of the values at the specified indices, but also
+    # raises an exception when one of the keys can't be found.
+    #
+    #   hash = ActiveSupport::HashWithIndifferentAccess.new
+    #   hash[:a] = 'x'
+    #   hash[:b] = 'y'
+    #   hash.fetch_values('a', 'b') # => ["x", "y"]
+    #   hash.fetch_values('a', 'c') { |key| 'z' } # => ["x", "z"]
+    #   hash.fetch_values('a', 'c') # => KeyError: key not found: "c"
+    def fetch_values(*indices, &block)
+      indices.collect { |key| fetch(key, &block) }
+    end if Hash.method_defined?(:fetch_values)
+
     # Returns a shallow copy of the hash.
     #
     #   hash = ActiveSupport::HashWithIndifferentAccess.new({ a: { b: 'b' } })
diff --git a/activesupport/test/hash_with_indifferent_access_test.rb b/activesupport/test/hash_with_indifferent_access_test.rb
index b1177c6c15..d68add46cd 100644
--- a/activesupport/test/hash_with_indifferent_access_test.rb
+++ b/activesupport/test/hash_with_indifferent_access_test.rb
@@ -166,6 +166,18 @@ class HashWithIndifferentAccessTest < ActiveSupport::TestCase
     assert_equal [1, 2], @mixed.values_at(:a, :b)
   end
 
+  def test_indifferent_fetch_values
+    skip unless Hash.method_defined?(:fetch_values)
+
+    @mixed = @mixed.with_indifferent_access
+
+    assert_equal [1, 2], @mixed.fetch_values("a", "b")
+    assert_equal [1, 2], @mixed.fetch_values(:a, :b)
+    assert_equal [1, 2], @mixed.fetch_values(:a, "b")
+    assert_equal [1, "c"], @mixed.fetch_values(:a, :c) { |key| key }
+    assert_raise(KeyError) { @mixed.fetch_values(:a, :c) }
+  end
+
   def test_indifferent_reading
     hash = HashWithIndifferentAccess.new
     hash["a"] = 1
diff --git a/guides/source/active_record_callbacks.md b/guides/source/active_record_callbacks.md
index de0ef7c4e5..b1705855d0 100644
--- a/guides/source/active_record_callbacks.md
+++ b/guides/source/active_record_callbacks.md
@@ -117,6 +117,10 @@ Here is a list with all the available Active Record callbacks, listed in the sam
 
 WARNING. `after_save` runs both on create and update, but always _after_ the more specific callbacks `after_create` and `after_update`, no matter the order in which the macro calls were executed.
 
+NOTE: `before_destroy` callbacks should be placed before `dependent: :destroy`
+associations (or use the `prepend: true` option), to ensure they execute before
+the records are deleted by `dependent: :destroy`.
+
 ### `after_initialize` and `after_find`
 
 The `after_initialize` callback will be called whenever an Active Record object is instantiated, either by directly using `new` or when a record is loaded from the database. It can be useful to avoid the need to directly override your Active Record `initialize` method.
diff --git a/guides/source/rails_on_rack.md b/guides/source/rails_on_rack.md
index 340933c7ee..f25b185fb5 100644
--- a/guides/source/rails_on_rack.md
+++ b/guides/source/rails_on_rack.md
@@ -20,9 +20,9 @@ Introduction to Rack
 
 Rack provides a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.
 
-* [Rack API Documentation](http://rack.github.io/)
-
-Explaining Rack is not really in the scope of this guide. In case you are not familiar with Rack's basics, you should check out the [Resources](#resources) section below.
+Explaining how Rack works is not really in the scope of this guide. In case you
+are not familiar with Rack's basics, you should check out the [Resources](#resources)
+section below.
 
 Rails on Rack
 -------------
@@ -74,7 +74,7 @@ And start the server:
 $ rackup config.ru
 ```
 
-To find out more about different `rackup` options:
+To find out more about different `rackup` options, you can run:
 
 ```bash
 $ rackup --help
@@ -89,7 +89,8 @@ Action Dispatcher Middleware Stack
 
 Many of Action Dispatcher's internal components are implemented as Rack middlewares. `Rails::Application` uses `ActionDispatch::MiddlewareStack` to combine various internal and external middlewares to form a complete Rails Rack application.
 
-NOTE: `ActionDispatch::MiddlewareStack` is Rails equivalent of `Rack::Builder`, but built for better flexibility and more features to meet Rails' requirements.
+NOTE: `ActionDispatch::MiddlewareStack` is Rails' equivalent of `Rack::Builder`,
+but is built for better flexibility and more features to meet Rails' requirements.
 
 ### Inspecting Middleware Stack