name: dotnet-efcore-patterns
description: Entity Framework Core best practices including NoTracking by default, migration management, dedicated migration services, and common pitfalls to avoid.

Entity Framework Core Patterns

When to Use This Skill

Use this skill when:
- Setting up EF Core in a new project
- Optimizing query performance
- Managing database migrations
- Integrating EF Core with .NET Aspire
- Debugging change tracking issues

Core Principles

1. NoTracking by Default - Most queries are read-only; opt-in to tracking
2. Never Edit Migrations Manually - Always use CLI commands
3. Dedicated Migration Service - Separate migration execution from application startup
4. ExecutionStrategy for Retries - Handle transient database failures
5. Explicit Updates - When NoTracking, explicitly mark entities for update

Quick Start

NoTracking by Default

public class ApplicationDbContext : DbContext
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
        : base(options)
    {
        // Disable change tracking by default for read-only queries
        ChangeTracker.QueryTrackingBehavior = QueryTrackingBehavior.NoTracking;
    }

    public DbSet<Order> Orders => Set<Order>();
}

Read-Only Queries

// Works normally with NoTracking
var orders = await _db.Orders
    .Where(o => o.CustomerId == customerId)
    .ToListAsync();

Updates with NoTracking

// Must explicitly enable tracking or use Entry API
var order = await _db.Orders.FindAsync(id); // FindAsync tracks automatically
order.Status = OrderStatus.Shipped;
await _db.SaveChangesAsync();

// Or use Entry API
var order = await _db.Orders.AsNoTracking().FirstAsync(o => o.Id == id);
order.Status = OrderStatus.Shipped;
_db.Entry(order).State = EntityState.Modified;
await _db.SaveChangesAsync();

Migration Management

Create Migration

dotnet ef migrations add AddOrderStatusColumn --project MyApp.Infrastructure

Apply Migrations

# Development
dotnet ef database update --project MyApp.Infrastructure

# Production - use dedicated migration service

Remove Last Migration

dotnet ef migrations remove --project MyApp.Infrastructure

References

See detailed patterns and examples in the references/ folder:

• NoTracking Pattern - Configuration, read/write operations, pitfalls
• Migration Management - CLI commands, workflow, best practices
• Migration Service - .NET Aspire integration, dedicated service pattern
• Bulk Operations - ExecuteUpdate, ExecuteDelete for performance
• Common Pitfalls - Mistakes to avoid with change tracking
• Testing Patterns - In-memory vs TestContainers

Resources

• EF Core Documentation: https://learn.microsoft.com/en-us/ef/core/
• Migrations: https://learn.microsoft.com/en-us/ef/core/managing-schemas/migrations/
• Change Tracking: https://learn.microsoft.com/en-us/ef/core/change-tracking/