Query objects encapsulate complex database queries in reusable, testable classes. I use query objects when scopes become too complex or require parameters. Query objects compose smaller scopes, handle conditionals, and apply filtering logic. They're i

Form objects encapsulate form logic separate from models. I use form objects for multi-model forms, complex validations, or forms not directly mapping to models. Form objects include ActiveModel modules for validations and callbacks. They handle param

Rails migrations evolve database schema over time. I use change method for reversible migrations. Migrations create tables, add/remove columns, add indices. up and down methods provide explicit control. Irreversible migrations like data transformation

Factory Bot creates test data with minimal boilerplate. Factories define blueprints for model creation. I use traits for variations—published posts, admin users. Sequences generate unique values. Associations automatically create related records. Tran

Ruby's exception handling uses begin/rescue/ensure/end. I rescue specific exceptions before general ones. rescue catches exceptions; ensure runs cleanup code always. retry attempts operation again; raise re-raises exceptions. Custom exceptions inherit

Ruby's regex engine provides powerful text processing. I use =~ for matching, match for captures. Character classes \d, \w, \s match digits, words, whitespace. Quantifiers *, +, ?, {n,m} control repetition. Anchors ^ and $ match start/end. Groups () c

Rails conventions support RESTful API development. I use resourceful routing for standard CRUD operations. Controllers inherit from ActionController::API for API-only apps. JSON serialization with Jbuilder or Active Model Serializers structures respon

Rails caching dramatically improves performance by avoiding expensive computations and queries. Fragment caching caches view partials. Russian doll caching nests cache fragments for efficient invalidation. Low-level caching stores arbitrary data. Rail

Ruby's Enumerable module provides rich collection methods. map transforms elements; select/reject filter. reduce aggregates values. find returns first match; find_all returns all matches. group_by partitions by criteria. partition splits into two arra

Rails validations ensure data integrity before persistence. I create custom validators for complex business rules. Validators inherit from ActiveModel::Validator or ActiveModel::EachValidator. EachValidator validates individual attributes; Validator v

Ruby modules enable code sharing across classes without inheritance. I use include for instance methods, extend for class methods. prepend inserts module before class in method lookup. Concerns organize shared behavior—validations, scopes, association

ActiveRecord provides powerful query interface, but naive usage causes N+1 queries. includes eager loads associations in 2-3 queries. joins performs SQL JOINs for filtering. preload always uses separate queries; eager_load forces LEFT OUTER JOIN. I us