Guide: Dependency Injection and Lifetimes
The core package integrates Spectre.Console.Cli with Microsoft.Extensions.DependencyInjection through the DependencyInjectionTypeRegistrar and DependencyInjectionTypeResolver. This guide shows how to register services and control their lifetimes.
Configure the container
Call WithDIContainer on the builder to set up the DI registrar. You can pass an existing IServiceCollection and the default ServiceLifetime used by the registrar's Register calls:
var builder = new CommandAppBuilder()
.WithDIContainer(lifetime: ServiceLifetime.Singleton);
Register services in a startup class
Inside StartupBase.ConfigureServices, use the type registrar to register your services. The WithLifetimes extension exposes lifetime-aware registration helpers:
public override void ConfigureServices(ITypeRegistrar registrar)
{
registrar.WithLifetimes()
.RegisterSingleton<IGreetingService, GreetingService>()
.RegisterScoped<IUnitOfWork, UnitOfWork>()
.RegisterTransient<IReport, DailyReport>();
}
The lifetime helpers available on ISupportLifetimes are:
RegisterSingleton<TService, TImplementation>()andRegisterSingleton<TService>(TService instance)RegisterScoped<TService, TImplementation>()RegisterTransient<TService, TImplementation>()
Resolve services in commands
Commands and their dependencies are resolved from the container. Constructor-inject the services your command needs, and Spectre resolves them through the DependencyInjectionTypeResolver:
public sealed class GreetCommand : AsyncCommand
{
private readonly IGreetingService _greetings;
public GreetCommand(IGreetingService greetings) => _greetings = greetings;
protected override Task<int> ExecuteAsync(CommandContext context) =>
Task.FromResult(_greetings.Greet());
}
Access the service collection directly
When you need to register services outside a startup class (for example from an extension method), call CommandAppBuilder.GetServiceCollection to get the underlying IServiceCollection.