Ef Core Agent Skill

Entity Framework Core Best Practices

Your goal is to help me follow best practices when working with Entity Framework Core.

Data Context Design

• Keep DbContext classes focused and cohesive
• Use constructor injection for configuration options
• Override OnModelCreating for fluent API configuration
• Separate entity configurations using IEntityTypeConfiguration
• Consider using DbContextFactory pattern for console apps or tests

Entity Design

• Use meaningful primary keys (consider natural vs surrogate keys)
• Implement proper relationships (one-to-one, one-to-many, many-to-many)
• Use data annotations or fluent API for constraints and validations
• Implement appropriate navigational properties
• Consider using owned entity types for value objects

Performance

• Use AsNoTracking() for read-only queries
• Implement pagination for large result sets with Skip() and Take()
• Use Include() to eager load related entities when needed
• Consider projection (Select) to retrieve only required fields
• Use compiled queries for frequently executed queries
• Avoid N+1 query problems by properly including related data

Migrations

• Create small, focused migrations
• Name migrations descriptively
• Verify migration SQL scripts before applying to production
• Consider using migration bundles for deployment
• Add data seeding through migrations when appropriate

Querying

• Use IQueryable judiciously and understand when queries execute
• Prefer strongly-typed LINQ queries over raw SQL
• Use appropriate query operators (Where, OrderBy, GroupBy)
• Consider database functions for complex operations
• Implement specifications pattern for reusable queries

Change Tracking & Saving

• Use appropriate change tracking strategies
• Batch your SaveChanges() calls
• Implement concurrency control for multi-user scenarios
• Consider using transactions for multiple operations
• Use appropriate DbContext lifetimes (scoped for web apps)

Security

• Avoid SQL injection by using parameterized queries
• Implement appropriate data access permissions
• Be careful with raw SQL queries
• Consider data encryption for sensitive information
• Use migrations to manage database user permissions

Testing

• Use in-memory database provider for unit tests
• Create separate testing contexts with SQLite for integration tests
• Mock DbContext and DbSet for pure unit tests
• Test migrations in isolated environments
• Consider snapshot testing for model changes

When reviewing my EF Core code, identify issues and suggest improvements that follow these best practices.