Nullco 0.1.0-preview.1

Nullco

SQL-first ORM for C# powered by a Roslyn source generator. Nullco expands partial methods into ADO.NET code at compile time — no reflection, no expression-tree compilation, SQL stays next to your code.

Rather than treating INSERT or SELECT as something to swap out later, Nullco keeps SQL as an attribute living right next to the method that runs it. That "SQL lives beside the code" model is what sets Nullco apart from most other ORMs.

Nullco supports the major RDBMS engines: SQLite, PostgreSQL, SQL Server, MySQL, and Oracle. Switch the NullcoDialect MSBuild property to emit dialect-specific SQL from the same attribute. Built-in instrumentation for OpenTelemetry, ILogger, and Metrics ships out of the box.

Installation

dotnet add package Nullco --prerelease
dotnet add package Nullco.Abstractions --prerelease

Set the dialect in your <PropertyGroup>:

<PropertyGroup>
    <NullcoDialect>Sqlite</NullcoDialect>
</PropertyGroup>

Quick start

Define a record and a partial class repository:

using System.Data.Common;
using Nullco;

namespace MyApp;

public sealed record User(int Id, string Name);

public partial class UserRepository
{
    private readonly DbConnection _connection;
    public UserRepository(DbConnection connection) => _connection = connection;

    [NullcoQuery("INSERT INTO users (id, name) VALUES (@id, @name)")]
    public partial int Insert(int id, string name);

    [NullcoQuery("SELECT id, name FROM users WHERE id = @id")]
    public partial User? FindById(int id);
}

At build time, the source generator fills in the bodies of the partial methods. The emitted code is straightforward ADO.NET — building DbCommand instances directly, with no reflection involved.

using Microsoft.Data.Sqlite;
using MyApp;

await using var connection = new SqliteConnection("Data Source=:memory:");
await connection.OpenAsync();

await using (var ddl = connection.CreateCommand())
{
    ddl.CommandText = "CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT NOT NULL);";
    await ddl.ExecuteNonQueryAsync();
}

var repo = new UserRepository(connection);
repo.Insert(1, "alice");
var user = repo.FindById(1);
Console.WriteLine($"Found: {user?.Name}"); // Found: alice

Documentation

• Getting Started — minimal setup walkthrough
• Design docs — design notes (v1 / v2 / v3)
• ADR — architectural decision records
• CHANGELOG

Status

v0.1.0-preview.1 — public preview. The API is still gathering feedback before stabilization. Please reach out before adopting in production.

License

MIT © Kengo Asamizu