You're reading from An Atypical ASP.NET Core 5 Design Patterns Guide A SOLID adventure into architectural principles, design patterns, .NET 5, and C#

Product type Paperback

Published in Dec 2020

Publisher Packt

ISBN-13 9781789346091

Length 762 pages

Edition 1st Edition

Languages

Tools

.NET

Concepts

Design Patterns

Author (1):

Carl-Hugo Marcotte

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Table of Contents (27) Chapters

Preface

1. Section 1: Principles and Methodologies

2. Chapter 1: Introduction to .NET FREE CHAPTER

3. Chapter 2: Testing Your ASP.NET Core Application

4. Chapter 3: Architectural Principles

5. Section 2: Designing for ASP.NET Core

6. Chapter 4: The MVC Pattern using Razor

7. Chapter 5: The MVC Pattern for Web APIs

8. Chapter 6: Understanding the Strategy, Abstract Factory, and Singleton Design Patterns

9. Chapter 7: Deep Dive into Dependency Injection

10. Chapter 8: Options and Logging Patterns

11. Section 3: Designing at Component Scale

12. Chapter 9: Structural Patterns

13. Chapter 10: Behavioral Patterns

14. Chapter 11: Understanding the Operation Result Design Pattern

15. Section 4: Designing at Application Scale

16. Chapter 12: Understanding Layering

17. Chapter 13: Getting Started with Object Mappers

18. Chapter 14: Mediator and CQRS Design Patterns

19. Chapter 15: Getting Started with Vertical Slice Architecture

20. Chapter 16: Introduction to Microservices Architecture

21. Section 5: Designing the Client Side

22. Chapter 17: ASP.NET Core User Interfaces

23. Chapter 18: A Brief Look into Blazor

24. Assessment Answers

25. Acronyms Lexicon

26. Other Books You May Enjoy

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Revisiting the Singleton pattern

The Singleton pattern is obsolete, goes against the SOLID principles, and we replace it with a lifetime, as we've already seen. This section explores that lifetime and recreates the good old application state, which turns out to be nothing more than a singleton scoped dictionary.

We'll explore two examples here; one about the application state, in case you wondered where that feature disappeared to. Then, the Wishlist project also uses the singleton lifetime to provide an application-level feature. There are a few unit tests as well to play with the testability and to allow safe refactoring.

The application state

If you programmed ASP.NET using .NET Framework, or the "good" old classic ASP with VBScript, you might remember the application state. If you don't, the application state was a key/value dictionary that allowed you to store data globally in your application, shared between all sessions and requests. That is...