Book Image

Building Applications with Spring 5 and Kotlin

By : Miloš Vasić
Book Image

Building Applications with Spring 5 and Kotlin

By: Miloš Vasić

Overview of this book

Kotlin is being used widely by developers because of its light weight, built-in null safety, and functional and reactive programming aspects. Kotlin shares the same pragmatic, innovative and opinionated mindset as Spring, so they work well together. Spring when combined with Kotlin helps you to reach a new level of productivity. This combination has helped developers to create Functional Applications using both the tools together. This book will teach you how to take advantage of these developments and build robust, scalable and reactive applications with ease. In this book, you will begin with an introduction to Spring and its setup with Kotlin. You will then dive into assessing the design considerations of your application. Then you will learn to use Spring (with Spring Boot) along with Kotlin to build a robust backend in a microservice architecture with a REST based collaboration, and leverage Project Reactor in your application. You’ll then learn how to integrate Spring Data and Spring Cloud to manage configurations for database interaction and cloud deployment. You’ll also learn to use Spring Security to beef up security of your application before testing it with the JUnit framework and then deploying it on a cloud platform like AWS.
Table of Contents (12 chapters)

Creating database queries

Before we finish this chapter, we will introduce database queries to you. We will define several API calls that will trigger queries defined by us. Writing queries is simple. There are several ways to it. We will present the most common methodologies.

In the first example, we will introduce the API call that will query and return to us all the TODOs that are scheduled later than the date we provide. Open TodoRepository and extend it:

package com.journaler.api.repository 
 
import com.journaler.api.data.Todo 
import org.springframework.data.jpa.repository.Query 
import org.springframework.data.repository.CrudRepository 
 
/** 
 * String is the type for ID we use. 
 */ 
interface TodoRepository : CrudRepository<Todo, String> { 
 
    @Query("from Todo t where t.schedule > ?1") 
    fun findScheduledLaterThan(date: Long): Iterable<Todo...