TS.MediatR is a lightweight and flexible CQRS/Mediator library for .NET. It supports IRequest, INotification, IPipelineBehavior, and works seamlessly with Dependency Injection.
Install via NuGet:
dotnet add package TS.MediatR
using TS.MediatR;
services.AddMediatR(options =>
{
options.AddRegisterAssemblies(typeof(Program).Assembly);
options.AddOpenBehavior(typeof(LoggingBehavior<,>)); //with response
options.AddOpenBehavior(typeof(ValidationBehavior<>)); //no response
});Define a request and its corresponding handler:
With Response
public class GetUserQuery : IRequest<UserDto>
{
public int Id { get; set; }
}
public class GetUserQueryHandler : IRequestHandler<GetUserQuery, UserDto>
{
public Task<UserDto> Handle(GetUserQuery request, CancellationToken cancellationToken)
{
var user = new UserDto { Id = request.Id, Name = "Jhon Doe" };
return Task.FromResult(user);
}
}No Response
public class CreateUserCommand : IRequest
{
public string Name { get; set; }
}
public class GetUserQueryHandler : IRequestHandler<CreateUserCommand>
{
public Task Handle(GetUserQuery request, CancellationToken cancellationToken)
{
var user = new UserDto { Name = request.Name };
return Task.FromResult(user);
}
}Use ISender to send the request:
With Response
var result = await sender.Send(new GetUserQuery { Id = 1 });
Console.WriteLine(result.Name);No Response
await sender.Send(new CreateUserCommand { Name = "Jhon Doe" });Use IPipelineBehavior for cross-cutting concerns like logging, validation, etc.
With Response
public class LoggingBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
where TRequest : IRequest<TResponse>
{
public async Task<TResponse> Handle(TRequest request, RequesteHandlerDelete<TResponse> next, CancellationToken cancellationToken)
{
Console.WriteLine($"Request received: {typeof(TRequest).Name}");
var response = await next();
Console.WriteLine($"Response returned: {typeof(TResponse).Name}");
return response;
}
}No Response
public class ValidationBehavior<TRequest> : IPipelineBehavior<TRequest>
where TRequest : IRequest
{
public async Task Handle(TRequest request, RequesteHandlerDelete<TResponse> next, CancellationToken cancellationToken)
{
Console.WriteLine($"Request received: {typeof(TRequest).Name}");
await next();
Console.WriteLine($"Response returned: {typeof(TResponse).Name}");
return response;
}
}Define a notification and its handler:
public class ProductCreatedEvent : INotification
{
public Guid Id { get; set; }
public ProductCreatedEvent(Guid id)
{
Id = id;
}
}
public class SendEmailHandler : INotificationHandler<ProductCreatedEvent>
{
public Task Handle(ProductCreatedEvent notification, CancellationToken cancellationToken)
{
Console.WriteLine($"Id sent: {notification.Id}");
return Task.CompletedTask;
}
}Publish a notification:
await sender.Publish(new ProductCreatedEvent(product.Id));- ✅ Request/Response (
IRequest,IRequest<TResponse>) - ✅ Notifications (
INotification) - ✅ Pipeline behaviors (
IPipelineBehavior) - ✅ Dependency Injection ready
- ✅ Scoped resolution and handler chaining
- ✅ Fully async support
Licensed under the MIT License.