GSoft.Extensions.MediatR 0.1.0

GSoft.Extensions.MediatR

This library ensures that MediatR is registered in the dependency injection container as a singleton and also adds several behaviors:

• Activity-based OpenTelemetry instrumentation
• High-performance logging with Debug log level
• Data annotations support for request validation, similar to ASP.NET Core model validation
• Application Insights instrumentation (in a separate NuGet package)
• CQRS conventions and MediatR best practices with Roslyn analyers

Getting started

Use the AddMediator(params Assembly[] assemblies) extension method on your dependency injection services (IServiceCollection) to automatically register all the MediatR request handlers from a given assembly.

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

If you use Application Insights and want to instrument your handlers, you can install the dedicated NuGet package:

builder.Services.AddMediator(typeof(Program).Assembly).AddApplicationInsights();

Example

public sealed record SayHelloRequest([property: Required] string To) : IRequest<string>;

public sealed class SayHelloRequestHandler : IRequestHandler<SayHelloRequest, string>
{
    public Task<string> Handle(SayHelloRequest request, CancellationToken cancellationToken)
    {
        return Task.FromResult($"Hello {request.To}!");
    }
}

// [...]
var mediator = serviceProvider.GetRequiredService<IMediator>();
var result = await mediator.Send(new SayHelloRequest("world"));

// This throws RequestValidationException because SayHelloRequest.To is marked as required
await mediator.Send(new SayHelloRequest(null));

Included Roslyn analyzers

In order to change the severity of one of these diagnostic rules, use a .editorconfig file, for instance:

[*.cs]
dotnet_diagnostic.GMDTR01.severity = none

To learn more about how to configure or suppress code analysis warnings, read this documentation.

Building, releasing and versioning

The project can be built by running Build.ps1. It uses Microsoft.CodeAnalysis.PublicApiAnalyzers to help detect public API breaking changes. Use the built-in roslyn analyzer to ensure that public APIs are declared in PublicAPI.Shipped.txt, and obsolete public APIs in PublicAPI.Unshipped.txt.

A new preview NuGet package is automatically published on any new commit on the main branch. This means that by completing a pull request, you automatically get a new NuGet package.

When you are ready to officially release a stable NuGet package by following the SemVer guidelines, simply manually create a tag with the format x.y.z. This will automatically create and publish a NuGet package for this version.

License

Copyright © 2023, GSoft Group Inc. This code is licensed under the Apache License, Version 2.0. You may obtain a copy of this license at https://github.com/gsoft-inc/gsoft-license/blob/master/LICENSE.