Cursor rule

1---
2description: Ruby on Rails
3globs: *.rb
4alwaysApply: false
5---
6You are an expert in Ruby on Rails and PostgreSQL
7  
8## Code Style and Structure
9 
10- Write concise, idiomatic Ruby code with accurate examples.
11- Follow Rails conventions and best practices.
12- Use object-oriented and functional programming patterns as appropriate.
13- Prefer iteration and modularization over code duplication.
14- Use descriptive variable and method names (e.g., user_signed_in?, calculate_total).
15- Structure files according to Rails conventions (MVC, concerns, helpers, etc.).
16 
17## Naming Conventions
18 
19- Use snake_case for file names, method names, and variables.
20- Use CamelCase for class and module names.
21- Follow Rails naming conventions for models, controllers, and views.
22 
23## Ruby and Rails Usage
24 
25- Use Ruby 3.x features when appropriate (e.g., pattern matching, endless methods).
26- Leverage Rails' built-in helpers and methods.
27- Use ActiveRecord effectively for database operations.
28- Follow the official Ruby on Rails guides for best practices in routing, controllers, models, views, and other Rails components.
29 
30## Syntax and Formatting
31 
32- Follow the Ruby Style Guide (https://rubystyle.guide/)
33- Use Ruby's expressive syntax (e.g., unless, ||=, &.)
34- Prefer single quotes for strings unless interpolation is needed.
35 
36## Error Handling and Validation
37 
38- Use exceptions for exceptional cases, not for control flow.
39- Implement proper error logging and user-friendly messages.
40- Use ActiveModel validations in models.
41- Handle errors gracefully in controllers and display appropriate flash messages.
42 
43## UI and Styling
44 
45- Remember that data flows to the front end using Inertia.js
46- The Rails view layer is not used, front end is done using React, loaded by Inertia.js
47 
48## Internationalization (i18n)
49 
50- Properly define strings in locale yml files; use a nested directory structure for locale files to keep things organized.
51- Define strings for the frontend in yml files as well; use the i18n-js gem to generate json files for the front end.
52- Implement proper locale detection.
53- Use proper number and date formatting.
54- Use proper currency formatting.
55- Implement proper RTL support.
56 
57### Controller Patterns
58 
59- Using "decent exposure" gem for defining common queries in controllers
60- Custom `strong_params` method on ApplicationController for defining strong parameters
61- `sortable_fields` method on ApplicationController helps define sortable fields for React Table components
62 
63## Performance Optimization
64 
65- Use database indexing effectively.
66- Implement caching strategies (fragment caching, Russian Doll caching).
67- Use eager loading to avoid N+1 queries.
68- Optimize database queries using includes, joins, or select.
69 
70## Key Conventions
71 
72- Follow RESTful routing conventions.
73- Use concerns for shared behavior across models or controllers.
74- Implement service objects for complex business logic.
75- Use background jobs (e.g., Goodjob) for time-consuming tasks.
76 
77## Testing
78 
79- Write comprehensive tests using RSpec.
80- Follow TDD/BDD practices.
81- Use factories (FactoryBot) for test data generation.
82- Do not use `let` for locally available definitions. Only use `let` when passing the test subject to a test defined in another file, or if it's the simpler approach for that specific test.
83 
84  ### Unit Testing
85 
86  - Write thorough unit tests to validate individual functions and components.
87  - Follow patterns like Arrange-Act-Assert to ensure clarity and consistency in tests.
88  - Mock external dependencies and API calls to isolate unit tests.
89 
90  ### Integration Testing
91 
92  - Focus on user workflows to ensure app functionality.
93  - Set up and tear down test environments properly to maintain test independence.
94 
95  ### Inertia Testing
96 
97  - Inertia has its own set of rspec assertions, use them when appropriate to test inertia specific actions. Examples below:
98 
99```ruby
100    RSpec.describe '/events', inertia: true do
101      describe '#index' do
102        let!(:event) { Event.create!(title: 'Foo', start_date: '2024-02-21', description: 'Foo bar') }
103 
104        it "renders inertia component" do
105          get events_path
106 
107          # check the component
108          expect(inertia).to render_component 'Event/Index'
109          # or
110          expect_inertia.to render_component 'Event/Index'
111          # same as above
112          expect(inertia.component).to eq 'Event/Index'
113 
114          # props (including shared props)
115          expect(inertia).to have_exact_props({title: 'Foo', description: 'Foo bar'})
116          expect(inertia).to include_props({title: 'Foo'})
117 
118          # access props
119          expect(inertia.props[:title]).to eq 'Foo'
120 
121          # view data
122          expect(inertia).to have_exact_view_data({meta: 'Foo bar'})
123          expect(inertia).to include_view_data({meta: 'Foo bar'})
124 
125          # access view data
126          expect(inertia.view_data[:meta]).to eq 'Foo bar'
127        end
128      end
129    end
130```
131 
132## Security
133 
134- Implement proper authentication and authorization (e.g., Devise, Rolify, Pundit).
135- Use strong parameters in controllers, using the strong_params method defined in the strong_params.rb concern.
136- Protect against common web vulnerabilities (XSS, CSRF, SQL injection).
137