Book Image

Learning Spring Boot 2.0 - Second Edition

By : Greg L. Turnquist, Greg L. Turnquist
Book Image

Learning Spring Boot 2.0 - Second Edition

By: Greg L. Turnquist, Greg L. Turnquist

Overview of this book

Spring Boot provides a variety of features that address today's business needs along with today's scalable requirements. In this book, you will learn how to leverage powerful databases and Spring Boot's state-of-the-art WebFlux framework. This practical guide will help you get up and running with all the latest features of Spring Boot, especially the new Reactor-based toolkit. The book starts off by helping you build a simple app, then shows you how to bundle and deploy it to the cloud. From here, we take you through reactive programming, showing you how to interact with controllers and templates and handle data access. Once you're done, you can start writing unit tests, slice tests, embedded container tests, and even autoconfiguration tests. We go into detail about developer tools, AMQP messaging, WebSockets, security, and deployment. You will learn how to secure your application using both routes and method-based rules. By the end of the book, you'll have built a social media platform from which to apply the lessons you have learned to any problem. If you want a good understanding of building scalable applications using the core functionality of Spring Boot, this is the book for you.
Table of Contents (11 chapters)

Pulling data through a Mono/Flux and chain of operations

We have wired up a repository to interface with MongoDB through Spring Data. Now we can start hooking it into our ImageService.

The first thing we need to do is inject our repository into the service, like this:

    @Service 
    public class ImageService { 
      ... 
      private final ResourceLoader resourceLoader; 
 
      private final ImageRepository imageRepository; 
 
      public ImageService(ResourceLoader resourceLoader, 
       ImageRepository imageRepository) { 
         this.resourceLoader = resourceLoader; 
         this.imageRepository = imageRepository; 
      } 
      ... 
    } 

In the previous chapter, we loaded Spring's ResourceLoader. In this chapter, we are adding ImageRepository to our constructor.

Previously, we looked up the names of the existing uploaded files, and constructed a Flux of Image...