Modiator

A MediatR-style mediator library for .NET, built from scratch with C# Source Generators for high performance and compile-time safety.

Solution Structure

• Modiator.Core — Core abstractions and the main mediator implementation
• Modiator.SourceGenerator — Roslyn source generator for compile-time dispatcher generation and DI registration
• Modiator.Tests — Unit tests for core and generated code
• Modiator.SampleApp — Sample app demonstrating advanced usage and DI integration

Getting Started

1. Build the solution: dotnet build
2. Add your own requests, notifications, handlers, and pipeline behaviors in your application.
3. Register everything with a single line:

   services.AddModiator();

Key Features

• No runtime reflection for handler discovery
• Compile-time generated dispatcher for fast request/notification handling
• Pipeline behaviors for cross-cutting concerns
• Source-generated DI registration with filtering and lifetime options

Advanced Usage

Source-Generated DI Registration

You can register all handlers, behaviors, and the dispatcher with a single call:

services.AddModiator();

Customization Options

You can filter which types are registered and set default lifetimes:

services.AddModiator(options => {
    // Only register types in a specific namespace
    options.Filter = t => t.Namespace != null && t.Namespace.StartsWith("MyApp.Handlers");

    // Set default lifetimes
    options.DefaultHandlerLifetime = ServiceLifetime.Scoped;
    options.DefaultBehaviorLifetime = ServiceLifetime.Singleton;
    options.DefaultNotificationHandlerLifetime = ServiceLifetime.Transient;
});

• Filter: Only types passing the filter will be registered.
• Lifetimes: Each category (handler, behavior, notification handler) can have its own default lifetime (Transient, Scoped, or Singleton).

Example: Registering Only Your App's Handlers as Scoped

services.AddModiator(options => {
    options.Filter = t => t.Namespace != null && t.Namespace.StartsWith("MyApp.Handlers");
    options.DefaultHandlerLifetime = ServiceLifetime.Scoped;
});

How It Works

• The source generator discovers all handlers, notification handlers, and pipeline behaviors at compile time.
• It generates a dispatcher and a DI registration extension method (AddModiator).
• You can use the options to control which types are registered and their lifetimes.
• No manual registration is needed for any handler or behavior!

See the Modiator.SampleApp for a full demonstration.

See Also

• Sample App README — for a detailed walkthrough and output examples
• prd.md for a deep dive into the architecture and design.