Mecesoft.MediatR 1.1.0

Mecesoft.MediatR

Mecesoft.MediatR is a lightweight, dependency-injection-friendly mediator library for .NET. It supports requests, notifications, dependency-injection scopes, and ordered pipeline behaviors without a dependency on the MediatR package.

Current version: 1.1.0

Supports .NET 8 and .NET 10. Includes optimized request dispatch, improved pipeline execution, and backward-compatible notification publishing.

Project links

• GitHub repository
• NuGet package

Installation

Install the latest published version from NuGet:

dotnet add package Mecesoft.MediatR

Registration

Register handlers from one or more assemblies and, optionally, open pipeline behaviors:

using Mecesoft.MediatR;

builder.Services.AddMediatR(options =>
{
    options.AddRegisterAssemblies(typeof(Program).Assembly);
    options.AddOpenBehavior(typeof(LoggingBehavior<,>));
});

ISender and discovered handlers are registered as transient services. Resolve ISender from the request scope so handlers can safely consume scoped services such as DbContext.

Requests

Requests with a response implement IRequest<TResponse>:

public sealed record GetUser(Guid Id) : IRequest<User>;

public sealed class GetUserHandler(IUserRepository repository)
    : IRequestHandler<GetUser, User>
{
    public Task<User> Handle(
        GetUser request,
        CancellationToken cancellationToken) =>
        repository.GetAsync(request.Id, cancellationToken);
}

User user = await sender.Send(new GetUser(id), cancellationToken);

Void requests implement IRequest and use IRequestHandler<TRequest>. Cancellation tokens are passed to handlers and pipeline behaviors unchanged.

Pipeline behaviors

For response requests, a pipeline behavior declares both the request and response types:

public sealed class LoggingBehavior<TRequest, TResponse>
    : IPipelineBehavior<TRequest, TResponse>
    where TRequest : IRequest<TResponse>
{
    public async Task<TResponse> Handle(
        TRequest request,
        RequesteHandlerDelete<TResponse> next,
        CancellationToken cancellationToken = default)
    {
        return await next();
    }
}

Void requests use IPipelineBehavior<TRequest> and RequesteHandlerDelete. Pipeline behaviors execute in registration order and may short-circuit without constructing the request handler.

Notifications

Notification handlers run concurrently by default for compatibility with published versions. Applications whose handlers share scoped dependencies that are not concurrency-safe can opt into sequential execution during registration:

builder.Services.AddMediatR(options =>
{
    options.AddRegisterAssemblies(typeof(Program).Assembly);
    options.PublishNotificationsConcurrently = false;
});

Notification and request handler failures propagate to the caller without being wrapped in reflection exceptions.

Compatibility

The existing IRequest, IRequest<TResponse>, IRequestHandler, ISender, Sender, INotification, INotificationHandler, IPipelineBehavior, and AddMediatR APIs remain available. The legacy RequesteHandlerDelete delegate names are retained for source compatibility.

License

Mecesoft.MediatR is available under the MIT License.