Integrate with Active Model Attributes

[seanpdoyle]

The schema { ... } interface pre-dates the Active Model Attributes API (defined as early as v5.2.0), but clearly draws inspiration from Active Record's Database Schema and Attribute casting (which was extracted into ActiveModel::Attributes).

However, the type information captured in schema { ... } blocks or assigned as Hash arguments to schema= is purely inert metadata.

Proposal

This commit aims to integrate with ActiveModel::Model and ActiveModel::Attributes. Through the introduction of both modules, subclasses of ActiveResource::Base can benefit from type casting attributes and constructing instances with default values.

This commit makes minimally incremental changes, prioritizing backwards compatibility. The reliance on #respond_to_missing? and #method_missing is left largely unchanged. Similarly, the Schema interface continues to provide metadata about its attributes through the Schema#attr method (instead of reading from
ActiveModel::Attributes#attribute_names or
ActiveModel::Attributes.attribute_types).

API Changes

To cast values to their specified types, declare the Schema with the :cast_values set to true.

class Person < ActiveResource::Base
  schema cast_values: true do
    integer 'age'
  end
end

p = Person.new
p.age = "18"
p.age # => 18

To configure inheriting resources to cast values, set the cast_values class attribute:

class ApplicationResource < ActiveResource::Base
  self.cast_values = true
end

class Person < ApplicationResource
  schema do
    integer 'age'
  end
end

p = Person.new
p.age = "18"
p.age # => 18

To set all resources application-wide to cast values, set config.active_resource.cast_values:

  # config/application.rb
  config.active_resource.cast_values = true

[jlurena]

Is this a draft? Once you are done maybe we can combine both our feature enhancements (mine is here: #409) and create a new major version of this gem.

@rails @byroot thoughts?

[guilleiguaran]

@seanpdoyle do you mind rebasing this?

[seanpdoyle]

@guilleiguaran thank you for providing review and helping to merge open PRs!

I've rebased this to incorporate the latest changes. I'm happy that it's functional, and attribute integration (casting, method hooks, etc) will be a big win!

I'm still not entirely satisfied with the integration touchpoint. Ideally, ActiveResource::Base would mix-in ActiveModel::Attributes directly, but I haven't yet been able to implement this behavior in that style.

I'm curious if @rafaelfranca has an opinion on how this currently proposed implementation compares to a more direct integration.

Are there tasks included in rails/rails#50568 (currently marked for Rails' 8.2.0 milestone) that are worthwhile to consider as part of this integration?