Indeed, part of the intent of #44666 was to enable porting ActiveRecord::Normalization to ActiveModel. 😃

Looking through ActiveRecord::Normalization, I think all necessary dependencies are present in ActiveModel::AttributeRegistration, so porting it should now be straightforward. I would be happy to review such a PR.

I've opened #53887 to explore this. I've also opened #53886 as a somewhat related change, but Normalization can occur with send(:"#{name}=", send(name)) until #[] and #[]= exist.

Wow! Thank you! I did not expect this gets such a traction and gets resolved so quickly.

Can you open an issue reproducing the problem? I'm not sure I understand how these tests can pass https://github.com/rails/rails/blob/513b6b1307484edee7904f3091cbc326ca7a9063/activemodel/test/cases/attributes/normalization_test.rb if something in normalizes depends on Active Record

Thanks for the quick follow-up!

The ActiveModel test case you mentioned passes because the sample class mixes in ActiveModel::Attributes, which defines the decorator stack and, in particular, the decorate_attributes hook that normalizes calls. As said, we are using aws-record-ruby and don't include that module. Aws::Record defines its own string_attr, integer_attr, etc. (a common pattern) which map into DynamoDB's attributes as macros (they're basically marshallers with setter/getters but never touching the AttributeSet of ActiveModel, so there’s no decorate_attributes method to hook into. To make it work, I guess we’d have to redefine every attribute twice (attribute :foo for ActiveModel, plus string_attr :foo for Aws::Record) or build a bridge layer that makes Aws::Record emit the decorators ActiveModel expects.

Here’s some example code:

require 'active_model'
require 'aws-record'

class NormalizedAwsRecord
  include ActiveModel::Model
  include Aws::Record
  include ActiveModel::Attributes::Normalization

  string_attr :name
  normalizes :name, with: ->(value) { value&.strip }
end

When you instantiate this class, that triggers:

NoMethodError: undefined method `decorate_attributes' for NormalizedAwsRecord:Class

So the macro works great when ActiveModel::Attributes is present (matching the tests), but it currently can’t be used with Aws::Record because that stack doesn’t expose the decorator helpers.

I understand that this is a "hey, it's the problem of the other gem" situation, but I just wanted to make you aware of that. As far as I know, some other Gems are also built on a similar pattern. The interesting thing is just, that I include for example

  include ActiveModel::Model
  include ActiveModel::Validations
  include ActiveModel::Validations::Callbacks

and that just works like a charm, giving me methods like persisted?, new_record? and destroyed? as well as callbacks.