dotnet-entity-framework-core

Entity Framework Core

Trigger On

• working on DbContext, migrations, model configuration, or EF queries
• reviewing tracking, loading, performance, or transaction behavior
• porting data access from EF6 or custom repositories to EF Core
• optimizing slow database queries

Documentation

• EF Core Overview
• Performance
• Efficient Querying
• Migrations
• What's New in EF Core 9

References

• patterns.md - Query patterns, tracking strategies, loading strategies, projections, compiled queries, pagination, and temporal tables
• anti-patterns.md - Common EF Core mistakes including N+1 queries, large contexts, generic repositories, and missing indexes

Workflow

1. Prefer EF Core for new development unless a documented gap requires Dapper or raw SQL
2. Keep DbContext lifetime scoped — align with unit of work
3. Review query translation — check generated SQL, avoid N+1
4. Treat migrations as first-class — reviewable, not throwaway
5. Be deliberate about provider behavior — cross-provider but not identical
6. Validate with query inspection — not just in-memory mental model

DbContext Patterns

Basic Configuration

public class AppDbContext : DbContext
{
    public DbSet<Product> Products => Set<Product>();
    public DbSet<Order> Orders => Set<Order>();

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.ApplyConfigurationsFromAssembly(typeof(AppDbContext).Assembly);
    }
}

// Entity Configuration (Fluent API)
public class ProductConfiguration : IEntityTypeConfiguration<Product>
{
    public void Configure(EntityTypeBuilder<Product> builder)
    {
        builder.HasKey(p => p.Id);
        builder.Property(p => p.Name).HasMaxLength(200).IsRequired();
        builder.HasIndex(p => p.Sku).IsUnique();
        builder.HasMany(p => p.OrderItems).WithOne(oi => oi.Product);
    }
}