Lazy loading in loop (ARCH206)

Key dotnet.ef.lazy-loading-in-loop · Severity warning · Category ef

With lazy loading enabled, each navigation access inside a loop silently triggers an extra query.

Incorrect

var customers = await _db.Customers.ToListAsync();
foreach (var c in customers)
{
    total += c.Orders.Sum(o => o.Total); // lazy load per customer
}

Correct

var customers = await _db.Customers
    .Include(c => c.Orders)
    .ToListAsync();
foreach (var c in customers)
{
    total += c.Orders.Sum(o => o.Total);
}

Fix

Pre-load related collections with Include().