Deprecated autoload during initialize

app/types/active_support/duration/type.rb

@@ -1,12 +1,10 @@
-class ActiveSupport::Duration
-  class Type < ActiveModel::Type::String
-    def cast(value)
-      return value if value.nil? || value.is_a?(ActiveSupport::Duration)
-      ActiveSupport::Duration.parse value
-    end
+class ActiveSupport::Duration::Type < ActiveModel::Type::String
+  def cast(value)
+    return value if value.nil? || value.is_a?(ActiveSupport::Duration)
+    ActiveSupport::Duration.parse value
+  end
 
-    def serialize(duration)
-      duration ? duration.iso8601 : nil
-    end
+  def serialize(duration)
+    duration ? duration.iso8601 : nil
   end
 end

config/initializers/types.rb

@@ -1 +1,3 @@
-ActiveRecord::Type.register :duration, ActiveSupport::Duration::Type
+ActiveSupport.on_load :active_record do
+  ActiveRecord::Type.register :duration, ActiveSupport::Duration::Type
+end