rails-state-machines

State machines in Rails models use AASM to define explicit states, transitions, and callbacks. Define states like pending → confirmed → shipped, add guard conditions to control which transitions are allowed, and persist the current state in the database as a single source of truth for your workflow.

Callbacks in state transitions are hooks that execute side effects when a model changes state. Use them to trigger notifications, update related records, or log events—for example, sending a confirmation email when an order transitions from pending to confirmed.

Yes, guarded transitions in Rails state machines let you define conditions that must be met before allowing a state change. Guards enforce business rules—for example, preventing an order from shipping unless payment is confirmed—ensuring only valid transitions occur.

Model order lifecycles by mapping real-world stages to explicit states (pending, confirmed, shipped, delivered) and defining allowed transitions between them. Include optional paths like cancellation, and use callbacks to handle side effects at each stage, keeping all state logic in one place.

State machines enforce valid transitions, prevent invalid states, and centralize business logic in one source of truth persisted in the database. This eliminates silent bugs from typos or inconsistent state values and makes workflows testable and auditable.

State machines excel for order processing, user account provisioning, document approval flows, and payment processing—any workflow with distinct stages, conditional transitions, and side effects tied to state changes.