1 files changed, 7 insertions, 9 deletions
diff --git a/activerecord/lib/active_record/validations/uniqueness.rb b/activerecord/lib/active_record/validations/uniqueness.rb
index a376e2a17f..13053beb78 100644
--- a/activerecord/lib/active_record/validations/uniqueness.rb
+++ b/activerecord/lib/active_record/validations/uniqueness.rb
@@ -11,15 +11,14 @@ module ActiveRecord
       end
 
       def validate_each(record, attribute, value)
-        return unless should_validate?(record)
         finder_class = find_finder_class_for(record)
         table = finder_class.arel_table
         value = map_enum_attribute(finder_class, attribute, value)
 
         relation = build_relation(finder_class, table, attribute, value)
-        if record.persisted? && finder_class.primary_key.to_s != attribute.to_s
+        if record.persisted?
           if finder_class.primary_key
-            relation = relation.where.not(finder_class.primary_key => record.id)
+            relation = relation.where.not(finder_class.primary_key => record.id_was)
           else
             raise UnknownPrimaryKey.new(finder_class, "Can not validate uniqueness for persisted record without primary key.")
           end
@@ -57,14 +56,13 @@ module ActiveRecord
           value = value.attributes[reflection.klass.primary_key] unless value.nil?
         end
 
-        attribute_name = attribute.to_s
-
         # the attribute may be an aliased attribute
-        if klass.attribute_aliases[attribute_name]
-          attribute = klass.attribute_aliases[attribute_name]
-          attribute_name = attribute.to_s
+        if klass.attribute_alias?(attribute)
+          attribute = klass.attribute_alias(attribute)
         end
 
+        attribute_name = attribute.to_s
+
         column = klass.columns_hash[attribute_name]
         cast_type = klass.type_for_attribute(attribute_name)
         value = cast_type.serialize(value)
@@ -82,7 +80,7 @@ module ActiveRecord
         if value.nil?
           klass.unscoped.where(comparison)
         else
-          bind = Relation::QueryAttribute.new(attribute.to_s, value, Type::Value.new)
+          bind = Relation::QueryAttribute.new(attribute_name, value, Type::Value.new)
           klass.unscoped.where(comparison, bind)
         end
       rescue RangeError