ActiveModel: Rails’ Framework for Non-Persistent Models

ActiveModel brings Rails conventions to plain Ruby objects, letting you use validation, dirty tracking, and form bindings without a database. Think of it as ActiveRecord's stripped-down cousin for non-persistent models. Key modules include AttributeAssignment (mass assignment), Validations (familiar rules like presence checks), Dirty Tracking (see what changed), and Conversion (Rails URL helpers). Hello world. Example: A UserForm class can include ActiveModel::Model, define attributes, add validations, and track changes via changes_applied. It works with form_for just like ActiveRecord models but might save via API calls instead of a database. Use cases: form objects, API client wrappers, service objects that need validations. Lets you keep Rails patterns consistent even when you’re not hitting the database. Not magic – just thoughtful reuse of Rails’ internal interfaces. Use modules à la carte or bundle them via ActiveModel::Model. Makes your POROs play nice with the Rails ecosystem.

Status	Draft
Publish at
Content	ActiveModel brings Rails conventions to plain Ruby objects, letting you use validation, dirty tracking, and form bindings without a database. Think of it as ActiveRecord's stripped-down cousin for non-persistent models. Key modules include AttributeAssignment (mass assignment), Validations (familiar rules like presence checks), Dirty Tracking (see what changed), and Conversion (Rails URL helpers). Hello world. Example: A UserForm class can include ActiveModel::Model, define attributes, add validations, and track changes via changes_applied. It works with form_for just like ActiveRecord models but might save via API calls instead of a database. Use cases: form objects, API client wrappers, service objects that need validations. Lets you keep Rails patterns consistent even when you’re not hitting the database. Not magic – just thoughtful reuse of Rails’ internal interfaces. Use modules à la carte or bundle them via ActiveModel::Model. Makes your POROs play nice with the Rails ecosystem.