Antipattern: Anemic Domain Model

The smell

• Models containing only validations, associations, and scopes — no verbs
• app/services/ full of *Service / *UseCase classes that orchestrate model attribute changes
• "Where does X happen?" → "search services/"
• Tests stub the services rather than exercising the models

Why it hurts

• Behavior is hard to discover — readers have to know the service exists
• Conditional dispatch creeps into services because models can't answer questions about themselves
• Every new verb is a new class with #call, plus a spec, plus wiring
• Encourages procedural style; weakens domain reasoning

The fix

• Put behavior on the model. A Post should know how to publish itself
• Extract a concern if the behavior has its own cluster of methods
• Extract a PORO named as a noun (PostPublication) — but the entry point stays on the model
• This is core to the 37signals/DHH style: post.publish, not PublishPostService.call(post)