Codery.Mediator

Lightweight, high-performance mediator library for .NET. A focused replacement for MediatR, built for Codery projects.

Features

• Request/Response dispatching via IRequest<TResponse> and IRequestHandler<TRequest, TResponse>
• Notifications (multicast) via INotification and INotificationHandler<TNotification>
• Pipeline behaviors for cross-cutting concerns (logging, validation, etc.)
• Zero per-call reflection — cached generic wrapper pattern eliminates reflection overhead after first use
• Two-package design — Codery.Mediator.Abstractions has zero dependencies; Codery.Mediator adds DI support
• Multi-targeting: net10.0 + netstandard2.0

Quick Start

dotnet add package Codery.Mediator

Register in your DI container:

builder.Services.AddCoderyMediator(typeof(Program).Assembly);

With pipeline behaviors:

builder.Services.AddCoderyMediator(
    opts => opts.AddOpenBehavior(typeof(LoggingBehavior<,>)),
    typeof(Program).Assembly);

Define a request and handler

public record GetUser(int Id) : IRequest<UserDto>;

public class GetUserHandler : IRequestHandler<GetUser, UserDto>
{
    public Task<UserDto> Handle(GetUser request, CancellationToken cancellationToken)
    {
        // ...
        return Task.FromResult(new UserDto(request.Id, "Alice"));
    }
}

Send requests

app.MapGet("/users/{id}", async (int id, ISender sender) =>
    await sender.Send(new GetUser(id)));

Notifications

public record OrderPlaced(string OrderId) : INotification;

public class SendEmailHandler : INotificationHandler<OrderPlaced>
{
    public Task Handle(OrderPlaced notification, CancellationToken cancellationToken)
    {
        // Send email...
        return Task.CompletedTask;
    }
}

// Publish to all handlers
await publisher.Publish(new OrderPlaced("ORD-123"));

Migration from MediatR

1. Replace MediatR NuGet with Codery.Mediator
2. Find & replace: using MediatR; → using Codery.Mediator;
3. Replace services.AddMediatR(cfg => ...) → services.AddCoderyMediator(typeof(Program).Assembly)
4. IRequest (void) handlers use IRequestHandler<TRequest, Unit> (no shorthand IRequestHandler<TRequest>)
5. Pipeline behaviors: opts.AddOpenBehavior(typeof(MyBehavior<,>))

Packages

Package	Description
Codery.Mediator.Abstractions	Interfaces only. Zero dependencies. Reference from handler projects.
Codery.Mediator	Implementation + DI registration. Reference from startup/host project.

License

MIT