7 files changed, 19 insertions, 12 deletions
diff --git a/activemodel/lib/active_model/attribute_methods.rb b/activemodel/lib/active_model/attribute_methods.rb
index 166c6ac21f..b5c0b43b61 100644
--- a/activemodel/lib/active_model/attribute_methods.rb
+++ b/activemodel/lib/active_model/attribute_methods.rb
@@ -472,5 +472,9 @@ module ActiveModel
       def missing_attribute(attr_name, stack)
         raise ActiveModel::MissingAttributeError, "missing attribute: #{attr_name}", stack
       end
+
+      def _read_attribute(attr)
+        __send__(attr)
+      end
   end
 end
diff --git a/activemodel/lib/active_model/dirty.rb b/activemodel/lib/active_model/dirty.rb
index 6e0af99ad7..dc81f74779 100644
--- a/activemodel/lib/active_model/dirty.rb
+++ b/activemodel/lib/active_model/dirty.rb
@@ -179,13 +179,13 @@ module ActiveModel
     # Handles <tt>*_changed?</tt> for +method_missing+.
     def attribute_changed?(attr, from: OPTION_NOT_GIVEN, to: OPTION_NOT_GIVEN) # :nodoc:
       !!changes_include?(attr) &&
-        (to == OPTION_NOT_GIVEN || to == __send__(attr)) &&
+        (to == OPTION_NOT_GIVEN || to == _read_attribute(attr)) &&
         (from == OPTION_NOT_GIVEN || from == changed_attributes[attr])
     end
 
     # Handles <tt>*_was</tt> for +method_missing+.
     def attribute_was(attr) # :nodoc:
-      attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
+      attribute_changed?(attr) ? changed_attributes[attr] : _read_attribute(attr)
     end
 
     # Handles <tt>*_previously_changed?</tt> for +method_missing+.
@@ -226,7 +226,7 @@ module ActiveModel
 
       # Handles <tt>*_change</tt> for +method_missing+.
       def attribute_change(attr)
-        [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr)
+        [changed_attributes[attr], _read_attribute(attr)] if attribute_changed?(attr)
       end
 
       # Handles <tt>*_previous_change</tt> for +method_missing+.
@@ -239,7 +239,7 @@ module ActiveModel
         return if attribute_changed?(attr)
 
         begin
-          value = __send__(attr)
+          value = _read_attribute(attr)
           value = value.duplicable? ? value.clone : value
         rescue TypeError, NoMethodError
         end
diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index 5d3472802b..942b4fa9bb 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -172,8 +172,8 @@ module ActiveModel
     #   person.errors.messages # => {:name=>["cannot be nil", "must be specified"]}
     #   person.errors.values   # => [["cannot be nil", "must be specified"]]
     def values
-      messages.reject do |key, value|
-        value.empty?
+      messages.select do |key, value|
+        !value.empty?
       end.values
     end
 
@@ -182,8 +182,8 @@ module ActiveModel
     #   person.errors.messages # => {:name=>["cannot be nil", "must be specified"]}
     #   person.errors.keys     # => [:name]
     def keys
-      messages.reject do |key, value|
-        value.empty?
+      messages.select do |key, value|
+        !value.empty?
       end.keys
     end
 
diff --git a/activemodel/lib/active_model/type/string.rb b/activemodel/lib/active_model/type/string.rb
index c7e0208a5a..850cab962b 100644
--- a/activemodel/lib/active_model/type/string.rb
+++ b/activemodel/lib/active_model/type/string.rb
@@ -12,7 +12,12 @@ module ActiveModel
       private
 
         def cast_value(value)
-          ::String.new(super)
+          case value
+          when ::String then ::String.new(value)
+          when true then "t".freeze
+          when false then "f".freeze
+          else value.to_s
+          end
         end
     end
   end
diff --git a/activemodel/lib/active_model/validations/format.rb b/activemodel/lib/active_model/validations/format.rb
index b4b8d9f33c..98b3f6a8e5 100644
--- a/activemodel/lib/active_model/validations/format.rb
+++ b/activemodel/lib/active_model/validations/format.rb
@@ -1,4 +1,3 @@
-
 module ActiveModel
   module Validations
     class FormatValidator < EachValidator # :nodoc:
diff --git a/activemodel/lib/active_model/validations/numericality.rb b/activemodel/lib/active_model/validations/numericality.rb
index 995b331245..b82c85ddf4 100644
--- a/activemodel/lib/active_model/validations/numericality.rb
+++ b/activemodel/lib/active_model/validations/numericality.rb
@@ -104,7 +104,7 @@ module ActiveModel
     module HelperMethods
       # Validates whether the value of the specified attribute is numeric by
       # trying to convert it to a float with Kernel.Float (if <tt>only_integer</tt>
-      # is +false+) or applying it to the regular expression <tt>/\A[\+\-]?\d+\Z/</tt>
+      # is +false+) or applying it to the regular expression <tt>/\A[\+\-]?\d+\z/</tt>
       # (if <tt>only_integer</tt> is set to +true+).
       #
       #   class Person < ActiveRecord::Base
diff --git a/activemodel/lib/active_model/validations/presence.rb b/activemodel/lib/active_model/validations/presence.rb
index 6e8a434bbe..ce4106a5e1 100644
--- a/activemodel/lib/active_model/validations/presence.rb
+++ b/activemodel/lib/active_model/validations/presence.rb
@@ -1,4 +1,3 @@
-
 module ActiveModel
   module Validations
     class PresenceValidator < EachValidator # :nodoc: