Revert the change at ActiveModel::Errors#add_on_blank and fix in the

right place.

The EachValidator#validate already handle :allow_blank and :allow_nil,
correctly.

Closes #8622.

Fix #8621.

activemodel/lib/active_model/errors.rb

@@ -322,15 +322,9 @@ def add_on_empty(attributes, options = {})
     #   person.errors.messages
     #   # => {:name=>["can't be blank"]}
     def add_on_blank(attributes, options = {})
-      return if options[:allow_blank]
-
       Array(attributes).each do |attribute|
         value = @base.send(:read_attribute_for_validation, attribute)
-        if value.nil?
-          add(attribute, :blank, options) unless options[:allow_nil]
-        elsif value.blank?
-          add(attribute, :blank, options)
-        end
+        add(attribute, :blank, options) if value.blank?
       end
     end
 

activemodel/lib/active_model/validations/presence.rb

@@ -3,8 +3,8 @@ module ActiveModel
 
   module Validations
     class PresenceValidator < EachValidator # :nodoc:
-      def validate(record)
-        record.errors.add_on_blank(attributes, options)
+      def validate_each(record, attr_name, value)
+        record.errors.add(attr_name, :blank, options) if value.blank?
       end
     end
 

activemodel/test/cases/validations/presence_validation_test.rb

@@ -41,7 +41,7 @@ def test_accepts_array_arguments
   end
 
   def test_validates_acceptance_of_with_custom_error_using_quotes
-    Person.validates_presence_of :karma, :message => "This string contains 'single' and \"double\" quotes"
+    Person.validates_presence_of :karma, message: "This string contains 'single' and \"double\" quotes"
     p = Person.new
     assert p.invalid?
     assert_equal "This string contains 'single' and \"double\" quotes", p.errors[:karma].last
@@ -72,9 +72,9 @@ def test_validates_presence_of_for_ruby_class_with_custom_reader
   end
 
   def test_allow_nil
-    Topic.validates_presence_of(:title, :allow_nil => true)
+    Topic.validates_presence_of(:title, allow_nil: true)
 
-    t = Topic.new(:title => "something")
+    t = Topic.new(title: "something")
     assert t.valid?, t.errors.full_messages
 
     t.title = ""
@@ -90,9 +90,9 @@ def test_allow_nil
   end
 
   def test_allow_blank
-    Topic.validates_presence_of(:title, :allow_blank => true)
+    Topic.validates_presence_of(:title, allow_blank: true)
 
-    t = Topic.new(:title => "something")
+    t = Topic.new(title: "something")
     assert t.valid?, t.errors.full_messages
 
     t.title = ""