Global Query Filters & Owned Entities

// Entity with soft-delete flag
public class Post
{
    public int Id { get; set; }
    public string Title { get; set; } = "";
    public bool IsDeleted { get; set; }
}

// Configure in OnModelCreating
modelBuilder.Entity<Post>()
    .HasQueryFilter(p => !p.IsDeleted);

// All queries now implicitly add WHERE IsDeleted = 0:
var posts = await _db.Posts.ToListAsync();

public class AppDbContext : DbContext
{
    private readonly ICurrentUserService _user;

    public AppDbContext(DbContextOptions<AppDbContext> opt, ICurrentUserService user)
        : base(opt) => _user = user;

    protected override void OnModelCreating(ModelBuilder mb)
    {
        mb.Entity<Order>().HasQueryFilter(
            o => o.TenantId == _user.TenantId);
    }
}
// Every Order query automatically filters by TenantId

// Admin: see ALL posts including deleted
var allPosts = await _db.Posts
    .IgnoreQueryFilters()
    .ToListAsync();

// Restore a specific deleted post
var deleted = await _db.Posts
    .IgnoreQueryFilters()
    .FirstOrDefaultAsync(p => p.Id == 42);

if (deleted is not null)
{
    deleted.IsDeleted = false;
    await _db.SaveChangesAsync();
}

// Blog with soft-delete filter on Posts
var blog = await _db.Blogs
    .Include(b => b.Posts) // only non-deleted posts are included
    .FirstOrDefaultAsync(b => b.Id == 1);

// blog.Posts contains only active posts — the filter applied in the JOIN

public class Customer
{
    public int Id { get; set; }
    public string Name { get; set; } = "";
    public Address BillingAddress  { get; set; } = new();
    public Address ShippingAddress { get; set; } = new();
}

public class Address
{
    public string Street  { get; set; } = "";
    public string City    { get; set; } = "";
    public string ZipCode { get; set; } = "";
    public string Country { get; set; } = "";
}

modelBuilder.Entity<Customer>(entity =>
{
    entity.OwnsOne(c => c.BillingAddress, addr =>
    {
        addr.Property(a => a.Street).HasMaxLength(300);
        addr.Property(a => a.Country).HasMaxLength(2);
    });

    entity.OwnsOne(c => c.ShippingAddress);
});
// Table: Customers with columns:
// BillingAddress_Street, BillingAddress_City, ...
// ShippingAddress_Street, ShippingAddress_City, ...

modelBuilder.Entity<Customer>().OwnsOne(
    c => c.BillingAddress,
    addr => addr.ToTable("CustomerBillingAddresses"));

// Now BillingAddress columns are in a separate table
// with a FK back to CustomerId

public class Customer
{
    public int Id { get; set; }
    public IList<PhoneNumber> PhoneNumbers { get; set; } = new List<PhoneNumber>();
}

public class PhoneNumber
{
    public string Number { get; set; } = "";
    public string Type   { get; set; } = "";
}

modelBuilder.Entity<Customer>()
    .OwnsMany(c => c.PhoneNumbers,
        phone => phone.ToTable("CustomerPhones"));

// Base entity
public abstract class Payment { public int Id { get; set; } }
public class CardPayment  : Payment { public string CardLast4 { get; set; } = ""; }
public class BankPayment  : Payment { public string IBAN { get; set; } = ""; }

// All Payment subtypes in one table with a Discriminator column
// No extra config needed — EF Core handles TPH by default
var cards = await _db.Set<CardPayment>().ToListAsync();
// SQL: SELECT * FROM Payments WHERE Discriminator = 'CardPayment'

// Scoped tenant service
public class TenantContext
{
    public Guid TenantId { get; set; }
}

// DbContext uses it
modelBuilder.Entity<Invoice>().HasQueryFilter(
    inv => inv.TenantId == _tenantCtx.TenantId);
modelBuilder.Entity<Customer>().HasQueryFilter(
    c => c.TenantId == _tenantCtx.TenantId);

// Queries are automatically scoped:
var invoices = await _db.Invoices.ToListAsync();
// WHERE TenantId = 'current-tenant-guid'