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Spring Data and R2DBC by Example
Take a look at this tutorial that show you how use R2DBC in a Spring project.
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Join For FreeR2DBC is a project that enables us to develop reactive programs API with relational databases, as we can do with databases that natively offer reactive drivers, like for example, Mongo or Cassandra.
Spring Data R2DBC is an abstraction of Spring to use repositories that support R2DBC and allows us a functional approach to interact with a relational database.
I use the following:
- Gradle 6.7.1
- Scala 2.12.6 ( I like this language :) )
- JDK 15
- Intellij IDEA
- Spring Boot 2.4.4
The project structure is:
The Gradle file contains:
Groovy
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plugins {
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id 'org.springframework.boot' version '2.4.4'
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id 'io.spring.dependency-management' version '1.0.11.RELEASE'
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id 'java'
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id 'scala'
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}
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group 'org.mazp.admin'
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version '1.0-SNAPSHOT'
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repositories {
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mavenCentral()
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maven { url 'https://repo.spring.io/milestone' }
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maven { url 'https://repo.spring.io/snapshot' }
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}
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dependencies {
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testImplementation 'org.junit.jupiter:junit-jupiter-api:5.7.0'
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testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.7.0'
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implementation 'org.scala-lang:scala-library:2.12.6'
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testImplementation 'org.scalatest:scalatest_2.12:3.2.3'
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testImplementation 'org.scala-lang:scala-library:2.12.6'
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implementation 'org.springframework.boot:spring-boot-starter-webflux'
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implementation 'org.springframework.boot:spring-boot-starter-data-r2dbc'
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implementation 'dev.miku:r2dbc-mysql'
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implementation 'mysql:mysql-connector-java'
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}
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test { useJUnitPlatform() }
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sourceSets {
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main { scala { srcDirs = ['src/main/scala'] } }
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test { scala { srcDirs = ['src/test/scala'] } }
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}
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springBoot {
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mainClass = 'com.mazp.admin.Main'
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}
The properties files is:
Properties files
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spring.r2dbc.url=r2dbc:mysql://localhost:3306/admin_r2dbc
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spring.r2dbc.username=user_mysql
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spring.r2dbc.password=password_user_mysql
The next class is used to map a row with an object:
Scala
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package com.mazp.admin.model
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import org.springframework.data.annotation.Id
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import org.springframework.data.relational.core.mapping.Table
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@Table("admin")
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class AdminObject {
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@Id private var idAdmin:Integer = null
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private var adminCode:String = null
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private var description:String = null
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def getDescription() = description
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def setDescription(usr:String) = this.description = usr
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def getAdminCode() = adminCode
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def setAdminCode(ctId:String) = adminCode = ctId
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def getIdAdmin() = idAdmin
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def setIdAdmin(ctId:Integer) = idAdmin = ctId
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}
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The repository is:
Scala
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package com.mazp.admin.respository
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import com.mazp.admin.model.AdminObject
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import org.springframework.data.repository.reactive.ReactiveCrudRepository
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import reactor.core.publisher.Flux
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trait AdminRepository extends ReactiveCrudRepository[AdminObject, Integer ]{
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/**
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* This method uses the convention name
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* @param adminCode
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* @return
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*/
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def findByAdminCode(adminCode:String):Flux[AdminObject]
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}
The service class is:
Scala
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package com.mazp.admin.service
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import com.mazp.admin.respository.AdminRepository
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import org.springframework.beans.factory.annotation.Autowired
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import org.springframework.stereotype.Service
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@Service
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class AdminService (@Autowired val adminRepository: AdminRepository) {
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def getAdmin(adminCode:String) =
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adminRepository.findByAdminCode(adminCode)
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}
The controller class is:
Scala
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package com.mazp.admin.controller
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import com.mazp.admin.service.AdminService
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import org.springframework.beans.factory.annotation.Autowired
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import org.springframework.web.bind.annotation.{GetMapping, PathVariable, RequestMapping, RestControllerAdvice}
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@RestControllerAdvice
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@RequestMapping(Array("/admin"))
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class AdminController(@Autowired val adminService: AdminService) {
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@GetMapping(Array("/{adminCode}"))
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def route(@PathVariable adminCode: String) = {
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adminService.getAdmin(adminCode)
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}
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}
The main class:
Scala
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package com.mazp.admin
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import org.springframework.boot.SpringApplication
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import org.springframework.boot.autoconfigure.{SpringBootApplication}
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@SpringBootApplication
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class Main
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object Main extends App{
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SpringApplication.run(classOf[Main], args:_*)
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}
The table admin is:
MySQL
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CREATE TABLE `admin` (
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`id_admin` int NOT NULL AUTO_INCREMENT,
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`admin_code` varchar(45) NOT NULL,
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`description` varchar(45) DEFAULT NULL,
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PRIMARY KEY (`id_admin`),
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UNIQUE KEY `admin_code_UNIQUE` (`admin_code`)
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) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
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INSERT INTO `admin_r2dbc`.`admin`(`admin_code`,`description`)
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VALUES('ADMIN','Esto es para prueba R2DBC');
When you run the project, you can call:
Now, we use the curl command to test the service:
Spring Framework
Spring Data
Data (computing)
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