rails-best-practices

name	rails-best-practices
description	Rails best practices, antipatterns, and performance pitfalls. Covers controllers, models, views, routes, migrations, Active Record query optimization, timeout configuration, and common mistakes. Use when writing, reviewing, or refactoring Rails code. Sources: rails-bestpractices.com, rubocop/rails-style-guide, speedshop.co, ankane/the-ultimate-guide-to-ruby-timeouts.

Rails Best Practices & Antipatterns

Quick Antipattern Checklist

Run this first. Each item links to a detailed explanation in the supporting files.

• default_scope anywhere → remove it (controllers-models.md)
• after_save with email/queue → move to after_commit (controllers-models.md)
• .count before or after .each on same relation → use .size (active-record.md)
• .where in an AR instance method → extract to filtered association (active-record.md)
• any? before each on same relation → use present? or .load.any? (active-record.md)
• Time.now or Date.today → use Time.current (security-timeouts.md)
• rescue Exception → use rescue StandardError (security-timeouts.md)
• No index on foreign keys → add add_index (active-record.md)
• HTTP call with no timeout → add open + read timeouts (security-timeouts.md)
• User.all.each for 10k+ records → use find_each (active-record.md)
• Instance variable in partial → pass as local (controllers-models.md)
• Business logic in controller action → extract to service/model (controllers-models.md)
• save return value ignored → use save! or handle false (security-timeouts.md)
• update_attribute in production code → use update (with validations) (active-record.md)
• enum with array syntax → use hash syntax (active-record.md)

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Topic Index

Topic	File
Controllers (scope access, params, before_action, services)	controllers-models.md
Models (fat model rules, scopes, callbacks, law of demeter)	controllers-models.md
Active Record queries (N+1, count vs size, predicate methods)	active-record.md
AR model rules (enum, has_many, dependent, validations)	active-record.md
Views, Routes, Migrations	security-timeouts.md
Security (rescue, strong params, Brakeman, Time.current)	security-timeouts.md
Timeouts (DB, HTTP, Redis, Puma, Rack, ReDoS)	security-timeouts.md
Performance (memoization, select, caching)	security-timeouts.md