Question 1

How do I use state_machines with ActiveRecord?

Accepted Answer

Install the separate 'state_machines-activerecord' gem, then define your state machine in the model. It integrates with ActiveRecord callbacks for automatic persistence and supports implicit event transitions via attributes.

Question 2

State_machines vs aasm: which is better for Ruby projects?

Accepted Answer

State_machines offers more advanced features like async transitions and coordinated state guards, making it better for complex workflows. Aasm is simpler and lighter, suitable for basic state management without extra dependencies.

Question 3

Can I use async state machines in a Rails app?

Accepted Answer

Yes, but ensure you're on MRI Ruby 3.2+ and have the 'async' gem installed. Define state machines with async: true and use them within an Async context to avoid blocking, but note it won't work on JRuby or TruffleRuby.

Question 4

How to test state machine callbacks with RSpec?

Accepted Answer

Require 'state_machines/test_helper' and include it in your specs. Use assertions like assert_after_transition to verify callbacks are defined correctly, and assert_sm_triggers_event for indirect event testing.

Question 5

What are the performance implications of async state machines?

Accepted Answer

Async state machines add overhead from the 'async' and 'concurrent-ruby' gems, but they improve scalability for I/O-bound tasks. For CPU-heavy operations, sync mode is more efficient due to reduced context switching.

Question 6

How to define a dynamic state machine based on database data?

Accepted Answer

You can build state machines dynamically at runtime using the Machine class example in the README, but it requires manual setup and can be complex, as transitions must be defined programmatically rather than declaratively.

state_machines

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