Copilot instructions

1---
2description: Rails Models and Active Record Guide
3applyTo: "app/models/**/*.rb"
4---
5 
6# Rails Models and Active Record Guide
7 
8## Core Philosophy
9 
10- Models are the heart of your Rails application
11- Keep business logic and data integrity in models
12- Use database constraints to enforce rules
13- Design for clarity and maintainability
14- Trust Active Record's conventions
15 
16## Model Design Principles
17 
18- Focus models on their core domain responsibility
19- Keep models cohesive and loosely coupled
20- Use descriptive names that reflect business concepts
21- Avoid God objects - split large models when needed
22- Document complex business rules clearly
23 
24## Schema Management
25 
26- Always use the annotate gem for schema documentation
27- Keep schema annotations at the top of model files
28- Run annotate after every migration
29- Review schema changes carefully before committing
30- Document non-obvious column purposes
31 
32## Model Organization
33 
34- Order model contents consistently for readability
35- Place constants at the top
36- Group related elements together
37- Keep public interface minimal
38- Document complex logic thoroughly
39 
40## Associations Best Practices
41 
42- Define all relationships explicitly
43- Use appropriate dependent options
44- Consider bi-directional associations carefully
45- Avoid circular dependencies
46- Document association purposes when not obvious
47 
48## Validation Strategy
49 
50- Validate at the model level always
51- Use database constraints to match validations
52- Keep validation messages user-friendly
53- Group related validations together
54- Test all validation scenarios
55 
56## Database Constraints
57 
58- Add NOT NULL constraints for required fields
59- Use unique indexes for uniqueness validations
60- Implement foreign key constraints
61- Add check constraints for complex rules
62- Document constraint purposes in migrations
63 
64## Scopes and Queries
65 
66- Create scopes for commonly used queries
67- Keep scope names descriptive and intention-revealing
68- Chain scopes for complex queries
69- Avoid scopes with side effects
70- Use class methods for scopes with parameters
71 
72## Callbacks Guidelines
73 
74- Use callbacks sparingly and purposefully
75- Keep callback methods private
76- Avoid callbacks that touch other models
77- Document callback purposes clearly
78- Consider service objects for complex workflows
79 
80## Performance Considerations
81 
82- Always index foreign keys
83- Add indexes for frequently queried columns
84- Use counter caches for association counts
85- Implement includes to avoid N+1 queries
86- Profile queries before optimizing
87 
88## Concerns and Modules
89 
90- Extract shared behavior into concerns
91- Keep concerns focused on single responsibilities
92- Name concerns based on the behavior they provide
93- Document concern dependencies
94- Test concerns thoroughly
95 
96## Enums and Constants
97 
98- Use enums for status fields with fixed values
99- Define constants for magic numbers
100- Keep enum values meaningful
101- Document enum state transitions
102- Consider state machines for complex workflows
103 
104## Data Integrity
105 
106- Implement validations that match business rules
107- Use transactions for multi-step operations
108- Handle race conditions appropriately
109- Validate data consistency regularly
110- Plan for data migration scenarios
111 
112## Testing Models
113 
114- Test all validations thoroughly
115- Verify association behavior
116- Test scopes with various data sets
117- Check callback effects
118- Ensure data integrity in edge cases
119 
120## Migration Best Practices
121 
122- Keep migrations focused and reversible
123- Add indexes in the same migration as columns
124- Use strong data types
125- Document migration purposes
126- Test migrations up and down
127 
128## Active Record Patterns
129 
130- Use find_or_create_by for idempotent operations
131- Implement soft deletes when audit trails needed
132- Use optimistic locking for concurrent updates
133- Leverage Active Record's built-in features
134- Avoid raw SQL unless necessary
135 
136## Model Security
137 
138- Never trust user input directly
139- Use parameterized queries always
140- Implement attribute protection appropriately
141- Audit sensitive data access
142- Encrypt sensitive attributes
143 
144## Documentation Standards
145 
146- Document complex business logic
147- Explain non-obvious validations
148- Describe association purposes
149- Note performance considerations
150- Include usage examples for complex methods
151 
152## Common Anti-Patterns
153 
154- Avoid callbacks that send emails or call APIs
155- Don't put view logic in models
156- Prevent models from knowing about controllers
157- Skip validations only when absolutely necessary
158- Don't bypass Active Record without good reason
159 
160## Refactoring Guidelines
161 
162- Extract complex queries to scopes
163- Move multi-model logic to service objects
164- Split large models along domain boundaries
165- Keep methods small and focused
166- Maintain backward compatibility
167 
168## Best Practices Summary
169 
170- Trust Active Record conventions
171- Keep models focused on data and business rules
172- Use database constraints for data integrity
173- Write comprehensive tests
174- Document complex logic clearly
175 
176Remember: Models are the foundation of your Rails application. Keep them clean, well-tested, and focused on their core responsibilities.
177