Active Record: Power and Pitfalls
Active Record is one of Rails' greatest strengths, but it can also be a source of performance issues and maintainability headaches if used incorrectly.
1. Use Scopes for Reusable Queries
Chain scopes elegantly: Order.pending.recent.by_customer(user.id).total_above(100)
2. Be Careful with Callbacks
Callbacks create hidden side effects. Prefer explicit service objects for complex operations.
3. Use find_each for Large Datasets
User.find_each(batch_size: 1000) processes records in batches instead of loading all into memory.
4. Use Transactions for Data Integrity
Wrap related operations in ActiveRecord::Base.transaction to ensure all-or-nothing behavior.
5. Database Constraints Over Model Validations
Always add database-level constraints (null: false, unique indexes, foreign keys) in addition to model validations.
6. Use pluck for Simple Queries
User.where(active: true).pluck(:id) is far more efficient than .map(&:id).
Building a Rails application? Let us help you build it right.
