DotRMediator 1.0.0

DotRMediator

DotRMediator is a .NET library that implements the Mediator pattern in-process, inspired by MediatR. It decouples senders from handlers, supports CQRS architectures, and enables pipeline composition for cross-cutting concerns such as validation, logging, and exception handling.

Table of contents

• Why use it?
• Installation
• Quick start
• Features
• Documentation
• Running tests
• Comparison with MediatR
• License

Why use it?

DotRMediator centralizes application communication through typed messages:

• Commands/Queries (Request/Response): one handler per request
• Notifications/Events: fan-out to multiple handlers
• Pipeline Behaviors: middleware for cross-cutting concerns
• Stream Requests: asynchronous responses via IAsyncEnumerable<T>
• Exception Handling: handlers and actions for request failures

No heavy dependencies — only Microsoft.Extensions.DependencyInjection.

Installation

Add a project reference:

dotnet add package DotRMediator

Or reference the project directly:

dotnet add src/MyApp/MyApp.csproj reference src/DotRMediator/DotRMediator.csproj

Quick start

1. Define a request and its handler

public sealed record GetUserByIdQuery(int UserId) : IRequest<UserDto>;

public sealed class GetUserByIdHandler : IRequestHandler<GetUserByIdQuery, UserDto>
{
    public Task<UserDto> Handle(GetUserByIdQuery request, CancellationToken cancellationToken)
    {
        var user = new UserDto(request.UserId, "Jane Doe");
        return Task.FromResult(user);
    }
}

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

2. Register with the DI container

builder.Services.AddDotRMediator(cfg =>
{
    cfg.RegisterServicesFromAssembly(typeof(Program).Assembly);
    cfg.AddOpenBehavior(typeof(LoggingBehavior<,>));
});

3. Send the request via IMediator

public class UsersController : ControllerBase
{
    private readonly IMediator _mediator;

    public UsersController(IMediator mediator) => _mediator = mediator;

    [HttpGet("{id:int}")]
    public async Task<UserDto> Get(int id, CancellationToken cancellationToken)
    {
        return await _mediator.Send(new GetUserByIdQuery(id), cancellationToken);
    }
}

Features

See the full documentation for advanced examples.

Documentation

Running tests

dotnet test

The suite includes 14 unit tests covering request dispatch, notification publishing, pipeline behaviors, pre/post-processors, streams, and exception handling.

Comparison with MediatR

DotRMediator implements the core MediatR feature set:

License

This project is licensed under the terms of the LICENSE file.