.cursorrules for rails?
Cursor has since moved to a new .rules directory structure. But this file still works.
Rails 8 + Kamal + Claude 3.5 in Cursor Composer has been surprisingly efficient for hobby projects. Push a few lines, forget about it for months.
Here’s my .cursorrules. Assembled from X and the community—not my original work, just sharing what works.
You are an expert in Ruby on Rails, Hotwire (Turbo and Stimulus), and Tailwind CSS.
## Project
- Name: ""
- Description: ""
- How to interact with me:
1. Always think step by step and explain your thoughts before writing code
2. Re-think the problem and the solution before writing code. Never write code that could be handled by the framework or its gems (ie: pagination, sorting, etc.)
3. Always consider the overall architecture and design of the application.
4. Make sure to create documentation for all new code.
## Languages and frameworks
- Ruby
- Rails 8
- Hotwire (Turbo and Stimulus)
- Tailwind CSS
- Use hotwire for all dynamic interactions.
- Use tailwind css for styling.
- Use stimulus for all dynamic interactions.
- Use turbo for all page transitions.
- Use turbo-rails to ease the use of turbo in the application.
## Locales
- en-US for all code, comments, naming and documentation, rake tasks, logging, etc.
- fr-FR for all user-facing text on the website.
## Code Style and Structure
- Write concise, idiomatic Ruby code with accurate examples.
- Follow Rails conventions and best practices.
- Use object-oriented and functional programming patterns as appropriate.
- Prefer iteration and modularization over code duplication.
- Use descriptive variable and method names (e.g., user_signed_in?, calculate_total).
- Structure files according to Rails conventions (MVC, concerns, helpers, etc.).
- Write code that is easy to understand.
- Write code that is easy to maintain.
- Make rubocop happy.
- Write code that would make DHH proud.
## Naming Conventions
- Use snake_case for file names, method names, and variables.
- Use CamelCase for class and module names.
- Follow Rails naming conventions for models, controllers, and views.
## Ruby and Rails Usage
- Use Ruby 3.x features when appropriate (e.g., pattern matching, endless methods).
- Leverage Rails' built-in helpers and methods.
- Use ActiveRecord effectively for database operations.
## Syntax and Formatting
- Follow the Ruby Style Guide (https://rubystyle.guide/)
- Use Ruby's expressive syntax (e.g., unless, ||=, &.)
- Prefer single quotes for strings unless interpolation is needed.
## Error Handling and Validation
- Use exceptions for exceptional cases, not for control flow.
- Implement proper error logging and user-friendly messages.
- Use ActiveModel validations in models.
- Handle errors gracefully in controllers and display appropriate flash messages.
## UI and Styling
- Use Hotwire (Turbo and Stimulus) for dynamic, SPA-like interactions.
- Implement responsive design with Tailwind CSS.
- Use Rails view helpers and partials to keep views DRY.
## Performance Optimization
- Use database indexing effectively.
- Implement caching strategies (fragment caching, Russian Doll caching).
- Use eager loading to avoid N+1 queries.
- Optimize database queries using includes, joins, or select.
## Key Conventions
- Follow RESTful routing conventions.
- Use concerns for shared behavior across models or controllers.
- Implement service objects for complex business logic.
- Use background jobs (e.g., Sidekiq) for time-consuming tasks.
## Testing
- Write comprehensive tests using RSpec or Minitest.
- Follow TDD/BDD practices.
- Use factories (FactoryBot) for test data generation.
## Security
- Implement proper authentication and authorization (e.g., Devise, Pundit).
- Use strong parameters in controllers.
- Protect against common web vulnerabilities (XSS, CSRF, SQL injection).
## Ruby on Rails
- Follow the official Ruby on Rails guides for best practices in routing, controllers, models, views, and other Rails components.