JorgeCostaMacia.ValueObject.EfConverter 6.0.4

JorgeCostaMacia.ValueObject.EfConverter

Native EF Core value converters for JorgeCostaMacia.ValueObject value objects — one converter per family (value object <-> underlying value), applied explicitly per property. Provider-agnostic (works with Npgsql, SQL Server, SQLite, …).

Install

dotnet add package JorgeCostaMacia.ValueObject.EfConverter

Brings JorgeCostaMacia.ValueObject and Microsoft.EntityFrameworkCore (the provider-agnostic core — not a database provider). Your own provider (e.g. Npgsql.EntityFrameworkCore.PostgreSQL) builds on the same core, so there is no conflict; NuGet resolves EF Core to your provider's version.

Usage

Apply a converter

using JorgeCostaMacia.ValueObject.EfConverter.Infrastructure;

builder.Property(e => e.Email).HasConversion(new StringValueObjectConverter<Email>());

One converter per family — IntValueObjectConverter<>, StringValueObjectConverter<>, DecimalValueObjectConverter<>, … — closed over your concrete value object. Map each property explicitly: it keeps the mapped surface intentional (a transient value object never gets persisted by accident) and the column type under your control. Multi-field value objects (ranges) are not single-column and are not covered here.

The same converter serves required and nullable properties (Email and Email?): EF maps a null reference to a NULL column and only invokes the converter for non-null values. For a nullable property, pass the converter type — .HasConversion(typeof(StringValueObjectConverter<Email>)) — to avoid a nullable-reference warning (CS8620) on the instance overload.

Value object as a primary key

A value object works as a key via its converter (complex/owned types cannot be keys). Configure it explicitly, since a converted key is app-assigned:

builder.HasKey(e => e.Id);
builder.Property(e => e.Id)
    .HasConversion(new IntValueObjectConverter<UserId>())
    .ValueGeneratedNever();

Notes

• Rehydration goes through the value object's constructor (found by reflection, compiled once) — not the Create factory — so reads do not re-run domain validation on already-persisted data. The constructor may be non-public.
• Querying by the underlying value uses the value object's conversion operator, e.g. where (int)e.Id > 1000 or where ((string)e.Name).StartsWith("a").
• byte[]-backed value objects (ByteValueObject): byte[] is a mutable reference type, so EF Core needs a ValueComparer to detect changes by content rather than by reference. Value objects are immutable (you replace the whole object, which EF sees as a new reference), so this only matters if you mutate the array in place — an anti-pattern. If you do, configure a comparer on that property.

About

Part of shared-net.

Author: Jorge Costa Maciá — GitHub