rails-model-generator_skill

Overview

This skill creates Rails models using a strict TDD workflow: write the spec first, create factories, generate migrations, implement the model, then refactor. It ensures models are delivered with tests, proper database schemas, validations, associations, scopes, and common patterns like enums and callbacks. The flow reduces regressions and keeps behavior specification central to development.

How this skill works

You define model requirements (attributes, associations, validations) then generate an RSpec model spec and a FactoryBot factory. Run specs to see failing tests, generate and run the migration, add the model file, then implement validations, associations, enums, scopes, and instance methods until specs pass. The skill includes templates and a checklist to enforce RED → GREEN → REFACTOR discipline.

When to use it

• Creating a new Rails model and corresponding DB table
• Adding or changing model validations or associations
• Defining enums, scopes, or instance methods with test coverage
• Setting up factories for model-driven tests
• Enforcing test-first discipline on Rails 8.1 development

Best practices

• Write a clear requirements template before coding: attributes, associations, validations, scopes, callbacks
• Create model spec and factory first, run tests to observe RED state
• Include null constraints, defaults, and indexes in migrations
• Keep specs focused: associations, validations, scopes, and instance methods in separate examples
• Use FactoryBot traits for variants and after(:create) for dependent records
• Run migrations and specs iteratively until tests are GREEN, then refactor

Example use cases

• Add a User model with name, email, status enum, and organization association following TDD
• Introduce validations and unique indexes for an existing model while keeping tests as the source of truth
• Create polymorphic associations or counter caches with accompanying specs and migrations
• Implement soft-delete behavior with scopes and instance methods covered by tests
• Generate a resource (model + factory + spec + migration) for a feature branch to ensure safe merges