ruby

Ruby & Rails

Rails Conventions

• Fat models, skinny controllers
• Service objects for business logic that spans multiple models
• Concerns for shared model/controller behavior (use sparingly)
• Strong parameters in controllers for mass assignment protection
• Scopes for reusable query logic in models

Project Structure (Rails)

app/
  controllers/   HTTP handling only
  models/        ActiveRecord models + validations
  services/      Business logic (POROs)
  serializers/   JSON response shaping
  jobs/          Background jobs (Sidekiq/ActiveJob)
  mailers/       Email templates and delivery

Testing

• RSpec preferred: describe, context, it blocks
• FactoryBot for test data (not fixtures for complex scenarios)
• Request specs for API endpoints (not controller specs)
• let for lazy-loaded test data, let! when eager loading needed
• shared_examples for common behavior across models

ActiveRecord

• Use scopes for reusable queries: scope :active, -> { where(active: true) }
• find_each for batch processing (not each on large datasets)
• includes to prevent N+1 (use Bullet gem to detect)
• Transactions for multi-record operations that must succeed together
• Enum with prefix: enum :status, { active: 0, archived: 1 }, prefix: true

Ruby Style

• Two-space indentation
• Snake_case for methods and variables, CamelCase for classes
• Guard clauses for early returns: return unless valid?
• Frozen string literals: # frozen_string_literal: true at top of files
• Prefer each_with_object over inject for building collections

Common Pitfalls

• N+1 queries (use Bullet gem + includes)
• Callbacks creating hidden side effects (prefer explicit service calls)
• Long-running tasks in request cycle (use background jobs)
• Not indexing foreign keys in migrations