Fix attribute_before_type_cast for serialized attributes. Fixes #4837.

2 files changed, 10 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/serialization.rb b/activerecord/lib/active_record/attribute_methods/serialization.rb
index 0c8e4e4b9a..7efef73472 100644
--- a/activerecord/lib/active_record/attribute_methods/serialization.rb
+++ b/activerecord/lib/active_record/attribute_methods/serialization.rb
@@ -88,6 +88,14 @@ module ActiveRecord
           super
         end
       end
+
+      def read_attribute_before_type_cast(attr_name)
+        if serialized_attributes.include?(attr_name)
+          super.unserialized_value
+        else
+          super
+        end
+      end
     end
   end
 end
diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index a2ce620354..e87fba550b 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -209,6 +209,8 @@ module ActiveRecord
     # The dup method does not preserve the timestamps (created|updated)_(at|on).
     def initialize_dup(other)
       cloned_attributes = other.clone_attributes(:read_attribute_before_type_cast)
+      self.class.initialize_attributes(cloned_attributes)
+
       cloned_attributes.delete(self.class.primary_key)
 
       @attributes = cloned_attributes