PlainBytes.Mediation.Mediator 0.1.0

PlainBytes.Mediation

YAMI (Yet another mediator implementation). Opinionated Mediator implementation to serve the authors needs. With the aim to keep it free and open-source.

Getting Started

Installation

Add the NuGet package to your project (replace with actual package name if published):

dotnet add package PlainBytes.Mediation.Mediator

Usage

1. Setup Dependency Injection and Mediator

var services = new ServiceCollection();
services.AddMediator();

2. Register Handlers

Register your command, query, and notification handlers:

services.AddTransient<IRequestHandler<CreateUserCommand>, CreateUserCommandHandler>();
services.AddTransient<IRequestHandler<CreateUserWithIdCommand, int>, CreateUserWithIdCommandHandler>();
services.AddTransient<IRequestHandler<GetUserNameQuery, string>, GetUserNameQueryHandler>();
services.AddTransient<IRequestHandler<FailingQuery, string>, FailingQueryHandler>();
services.AddTransient<INotificationHandler<UserCreatedNotification>, SendToastNotificationHandler>();
services.AddTransient<INotificationHandler<UserCreatedNotification>, SendWelcomeEmailNotificationHandler>();

3. Build Service Provider and Get Mediator

var provider = services.BuildServiceProvider();
var mediator = provider.GetRequiredService<IMediator>();

4. Example Usages

Send a command (no return value):

await mediator.Send(new CreateUserCommand { UserName = "Alice" });

Send a command (with return value):

var userId = await mediator.Send(new CreateUserWithIdCommand { UserName = "Bob" });
Console.WriteLine($"Returned user id: {userId}");

Execute a query:

var userName = await mediator.Get(new GetUserNameQuery { UserId = userId });
Console.WriteLine($"Fetched user name: {userName}");

Publish a notification:

await mediator.Publish(new UserCreatedNotification { UserName = userName });

5. RequestResult Examples

TrySend and TryGet return a RequestResult:

var nameResult = await mediator.TrySend(new CreateUserCommand { UserName = "Charlie" });
Console.WriteLine($"TrySend result: {nameResult}");

var idResult = await mediator.TrySend(new CreateUserWithIdCommand { UserName = "Diana" });
Console.WriteLine($"TrySend result: {idResult}");

var userNameResult = await mediator.TryGet(new GetUserNameQuery { UserId = 42 });
Console.WriteLine($"TryGet result: {userNameResult}");

var failedResult = await mediator.TryGet(new FailingQuery());
Console.WriteLine($"TryGet failed result: {failedResult}");

6. Adding Logging Pipeline Behaviors

You can enable built-in logging behaviors for requests and notifications. These behaviors use Microsoft.Extensions.Logging.

// Basic exception logging for requests & notifications
services.AddLoggingPipelineBehaviors();

The basic logging behaviors log errors when a request handler or notification handler throws. For additional performance timing (logs successful completion time and failures):

// Logs execution time and errors for requests, and errors for notifications
services.AddPerformanceLoggingPipelineBehaviors();

Choose only one of AddLoggingPipelineBehaviors or AddPerformanceLoggingPipelineBehaviors depending on whether you want timing information.

For more examples, see the SampleApp/Program.cs file in this repository.