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Nest.js: A Progressive Node.js Framework

You're reading from  Nest.js: A Progressive Node.js Framework

Product type Book
Published in Nov 2019
Publisher Packt
ISBN-13 9781800204737
Pages 317 pages
Edition 1st Edition
Languages
Authors (5):
Greg Magolan Greg Magolan
Profile icon Greg Magolan
Patrick Housley Patrick Housley
Profile icon Patrick Housley
Adrien de Peretti Adrien de Peretti
Profile icon Adrien de Peretti
Jay Bell Jay Bell
Profile icon Jay Bell
David Guijarro David Guijarro
Profile icon David Guijarro
View More author details

Table of Contents (16) Chapters

Preface
1. Introduction 2. Overview 3. Nest.js authentication 4. Dependency Injection system of Nest.js 5. TypeORM 6. Sequelize 7. Mongoose 8. Web sockets 9. Microservices 10. Routing and request handling in Nest.js 11. OpenAPI (Swagger) Specification 12. Command Query Responsibility Separation (CQRS) 13. Architecture 14. Testing 15. Server-side Rendering with Angular Universal

Overview of Dependency Injection

Since Typescript 1.5 introduces the notion of the decorator, you can do meta-programing using the added metadata provided by using a decorator on different objects or properties, such as class, function, function parameters or class property. The meta-programing is the ability to write some code or program using the metadata describing an object. This type of program allows you to modify the functioning of a program using its own metadata. In our case this metadata is of interest to us, because it helps inject some object into another object, whose name is Dependency Injection.

By using the decorator, you can add metadata on any object or property linked to those decorators. This will define, for example, the type of object that takes the decorator, but it can also define all of the parameters needed by a function that are described in its metadata. To get or define metadata on any object, you can also use the reflect-metadata library in order to manipulate...

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