486: ActiveModel Everywhere

What It Covers

Adi and Sally explore using ActiveModel modules in non-database-backed Ruby classes to create consistent APIs across Rails applications, enabling validation, attributes, callbacks, and serialization without requiring ActiveRecord persistence layers.

Key Questions Answered

• •ActiveModel Attributes: Include ActiveModel modules in service objects and plain Ruby classes to get automatic attribute handling, instantiation patterns, and instance variable management without writing boilerplate code, maintaining consistency with ActiveRecord models throughout your application.
• •Resource-Oriented Design: Treat every Rails component as a resource with restful actions, even when not backed by database tables. This approach enables controllers to maintain identical structure and familiar save/persist patterns regardless of underlying implementation details or data storage mechanisms.
• •Validation Reuse: ActiveModel validations provide presence, uniqueness, and custom validators for non-database classes, generating standard Rails error objects. This eliminates reimplementing validation logic and ensures consistent error handling across database-backed and non-persisted objects in your application.
• •Testing Consistency: Using ActiveModel in plain Ruby objects enables standard Rails testing tools like FactoryBot and familiar test helpers. Without it, developers must recreate testing infrastructure manually, losing productivity and consistency when working outside traditional ActiveRecord models.