Trellis.EntityFrameworkCore 3.0.0-alpha.158

EF Core Integration

Thin integration layer that eliminates repetitive EF Core boilerplate when using Trellis value objects and Result<T>.

Installation

dotnet add package Trellis.EntityFrameworkCore

Quick Start

Register all Trellis value objects as scalar properties with a single line in ConfigureConventions:

using Trellis.EntityFrameworkCore;

public class AppDbContext : DbContext
{
    protected override void ConfigureConventions(ModelConfigurationBuilder configurationBuilder)
    {
        // Scans your assembly for CustomerId, OrderStatus, etc.
        // Also auto-scans Trellis.Primitives for EmailAddress, Url, PhoneNumber, etc.
        // Also auto-maps Money properties as owned types (Amount + Currency columns)
        configurationBuilder.ApplyTrellisConventions(typeof(CustomerId).Assembly);
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        // No HasConversion() boilerplate needed — just configure keys, indexes, constraints
        modelBuilder.Entity<Customer>(b =>
        {
            b.HasKey(c => c.Id);
            b.Property(c => c.Name).HasMaxLength(100).IsRequired();
            b.Property(c => c.Email).HasMaxLength(254).IsRequired();
        });
    }
}

Money Properties — Zero Configuration

Money properties are automatically mapped as owned types with proper column naming and precision. No OwnsOne calls needed — just declare Money properties on your entities and they work. This also applies when Money is declared on owned entity types, including items inside OwnsMany collections.

Maybe<Money> is also supported — it auto-configures as an optional owned type with nullable Amount/Currency columns, no OwnsOne needed.

Maybe<T> Properties — Source Generator + Convention

Maybe<T> is a readonly struct that EF Core cannot map as optional. Use partial properties — the source generator and MaybeConvention handle everything:

public partial class Customer
{
    public CustomerId Id { get; set; } = null!;

    public partial Maybe<PhoneNumber> Phone { get; set; }
    public partial Maybe<DateTime> SubmittedAt { get; set; }
}

No OnModelCreating configuration needed. When T is a composite owned type (e.g., Money), it creates an optional ownership navigation instead of a scalar column. Querying uses dedicated extensions:

var withoutPhone = await context.Customers.WhereNone(c => c.Phone).ToListAsync(ct);
var withPhone    = await context.Customers.WhereHasValue(c => c.Phone).ToListAsync(ct);
var matches      = await context.Customers.WhereEquals(c => c.Phone, phone).ToListAsync(ct);
var ordered      = await context.Customers.WhereHasValue(c => c.Phone).OrderByMaybe(c => c.Phone).ToListAsync(ct);

Indexes, bulk updates, and diagnostics also stay strongly typed:

modelBuilder.Entity<Customer>(builder => builder.HasTrellisIndex(c => c.Phone));

await context.Customers
    .Where(c => c.Id == customerId)
    .ExecuteUpdateAsync(setters => setters.SetMaybeValue(c => c.Phone, phone), ct);

var mappings = context.GetMaybePropertyMappings();
var debugView = context.ToMaybeMappingDebugString();

Result-Returning SaveChanges

// Returns Result<int> instead of throwing on conflicts or FK violations
var result = await context.SaveChangesResultAsync(ct);

// Returns Result<Unit> when you don't need the count
var result = await context.SaveChangesResultUnitAsync(ct);

Query Extensions

// Maybe-returning queries (no exception on missing)
Maybe<Customer> customer = await context.Customers
    .FirstOrDefaultMaybeAsync(c => c.Id == customerId, ct);

// Result-returning queries
Result<Customer> customer = await context.Customers
    .FirstOrDefaultResultAsync(
        c => c.Id == customerId,
        Error.NotFound("Customer", customerId),
        ct);

// Specification pattern
var activeSpec = new ActiveCustomerSpec();
var activeCustomers = await context.Customers
    .Where(activeSpec)
    .ToListAsync(ct);

Related Packages

• Trellis.Results — Core Result<T> and Maybe<T> types
• Trellis.Primitives — Value object base classes and built-in types
• Trellis.DomainDrivenDesign — Specification<T>, Entity<T>, Aggregate<T>

License

MIT — see LICENSE for details.