Advanced Dependency Injection in .NET Core: Patterns and Practices

Introduction

Dependency Injection (DI) is a fundamental design pattern in .NET Core that allows developers to build loosely coupled, maintainable, and testable applications. While basic DI usage is straightforward, advanced patterns can significantly improve the scalability and flexibility of your applications. In this article, we will explore advanced DI techniques, including custom service lifetimes, factory patterns, scoped services in background tasks, and how to handle circular dependencies in .NET Core.

1. Recap: Basic Dependency Injection in .NET Core

Before diving into advanced concepts, let’s quickly review the basics of DI in .NET Core:

• Transient: A new instance is created each time it is requested.
• Scoped: A new instance is created once per request.
• Singleton: A single instance is created and shared throughout the application lifetime.

Basic usage of DI in Startup.cs:

public void ConfigureServices(IServiceCollection services)
{
    services.AddTransient<IMyService, MyService>();
    services.AddScoped<IMyRepository, MyRepository>();
    services.AddSingleton<ILogger, Logger>();
}

2. Custom Service Lifetimes

Beyond the built-in lifetimes (Transient, Scoped, Singleton), you might need custom lifetimes…