Lifecycle management in Dependency Injection

This repository is reserved to provide an explanation of the three types of lifecycles modes used in Dependency Injection, in this case w/ .NET Core. The modes are Singleton, Scoped and Transient.

👀 Overview

Singleton

• Only one service instance was created during the app lifecycle.
• All requests to obtain this object will return the same instance.
• It's useful for objects shared by application, such as database connections or global configs.

Scoped

• We get a new instance with every request, or "Scope".
• Within the same scope, all requests will return the same instace of the object.
• It's useful for sharing resources during request processing without global sharing, as in web app.

Transient

• Is created every time it's requested.
• Each request to obtain this object will return a new instance.
• Useful for objects that don't need to be shared between different parts of the app.

✨ Hands On!

In this small project, you'll find three endpoints

In each of them, a service with a specific lifecycle mode was registered and this simple service returns the creation date of the object instance.

[GET] /singleton

An only instance of SingletonService is created and shared across all requests

builder.Services.AddSingleton<ISingletonService, SingletonService>()

Response body

{
  "creationDateTime": "2024-05-14 17:43:00.743"
}

[GET] /scoped

Two requests will have different instances of ScopedService and they return the same creation time because they are created in the same scope

builder.Services.AddScoped<IScopedService, ScopedService>()

Response body

{
  "firstInstanceDateTime": "2024-05-14 17:57:37.145",
  "secondInstanceDateTime": "2024-05-14 17:57:37.145",
  "areEqual": true
}

[GET] /transient

Two requests will have different instances of TransientService and they return different creation times

builder.Services.AddTransient<ITransientService, TransientService>()

Response body

{
  "firstInstanceDateTime": "2024-05-14 17:58:02.964",
  "secondInstanceDateTime": "2024-05-14 17:58:07.964",
  "areEqual": false
}

🔨 Built with .NET 8

🏃 Installing and Running

1. Clone this repo: https://github.com/kmlyteixeira/singleton-scoped-transient-dotnet
2. Run dotnet build to build this project
3. Run dotnet run
4. Open http://localhost:5225/swagger and be happy :)

📚 Learn more

1️⃣ Dependency injection in ASP.NET Core

2️⃣ Singleton Design Pattern

3️⃣ Differences Between Scoped, Transient, And Singleton Service