1 files changed, 11 insertions, 4 deletions
diff --git a/activerecord/lib/active_record/associations/has_one_association.rb b/activerecord/lib/active_record/associations/has_one_association.rb
index 41a75b820e..0fe9b2e81b 100644
--- a/activerecord/lib/active_record/associations/has_one_association.rb
+++ b/activerecord/lib/active_record/associations/has_one_association.rb
@@ -1,5 +1,5 @@
 module ActiveRecord
-  # = Active Record Belongs To Has One Association
+  # = Active Record Has One Association
   module Associations
     class HasOneAssociation < SingularAssociation #:nodoc:
       include ForeignAssociation
@@ -11,8 +11,15 @@ module ActiveRecord
 
         when :restrict_with_error
           if load_target
-            record = klass.human_attribute_name(reflection.name).downcase
-            owner.errors.add(:base, :"restrict_dependent_destroy.one", record: record)
+            record = owner.class.human_attribute_name(reflection.name).downcase
+            message = owner.errors.generate_message(:base, :'restrict_dependent_destroy.one', record: record, raise: true) rescue nil
+            if message
+              ActiveSupport::Deprecation.warn(<<-MESSAGE.squish)
+                The error key `:'restrict_dependent_destroy.one'` has been deprecated and will be removed in Rails 5.1.
+                Please use `:'restrict_dependent_destroy.has_one'` instead.
+              MESSAGE
+            end
+            owner.errors.add(:base, message || :'restrict_dependent_destroy.has_one', record: record)
             throw(:abort)
           end
 
@@ -58,7 +65,7 @@ module ActiveRecord
             when :destroy
               target.destroy
             when :nullify
-              target.update_columns(reflection.foreign_key => nil)
+              target.update_columns(reflection.foreign_key => nil) if target.persisted?
           end
         end
       end