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EF Core Advanced Patterns

DbContext Best Practices​

Scoped Lifetime​

builder.Services.AddDbContext<AppDbContext>(options =>
    options.UseSqlServer(connectionString));

DbContext Pooling​

builder.Services.AddDbContextPool<AppDbContext>(options =>
    options.UseSqlServer(connectionString));

Query Optimization​

❌ N+1 Problem​

var orders = await context.Orders.ToListAsync();
foreach (var order in orders)
{
    var customer = await context.Customers.FindAsync(order.CustomerId); // N queries!
}

✅ Eager Loading​

var orders = await context.Orders
    .Include(o => o.Customer)
    .ToListAsync();

✅ Projection (Best)​

var orders = await context.Orders
    .Select(o => new OrderDto
    {
        Id = o.Id,
        CustomerName = o.Customer.Name
    })
    .ToListAsync();

Split Queries​

var posts = await context.Posts
    .Include(p => p.Comments)
    .Include(p => p.Tags)
    .AsSplitQuery()  // Prevents cartesian explosion
    .ToListAsync();

No Tracking​

var products = await context.Products
    .AsNoTracking()  // Read-only, better performance
    .ToListAsync();

Global Query Filters​

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<Post>().HasQueryFilter(p => !p.IsDeleted);
}

Compiled Queries​

private static readonly Func<AppDbContext, int, Task<Product>> GetProductById =
    EF.CompileAsyncQuery((AppDbContext context, int id) =>
        context.Products.FirstOrDefault(p => p.Id == id));

var product = await GetProductById(context, productId);

Bulk Operations​

// EF Core 7+
await context.Products
    .Where(p => p.Price < 10)
    .ExecuteUpdateAsync(s => s.SetProperty(p => p.Price, p => p.Price * 1.1));

await context.Products
    .Where(p => p.IsDeleted)
    .ExecuteDeleteAsync();