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Integration of Spring Boot 3.1 Webflux with MongoDB + Docker

fResult
7 min readOct 27, 2023

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Photo by Florian Wächter on Unsplash

The image doesn’t relate to the content. 😅

Disclaimer

I’m not a Java Developer.
So, this blog post is just a record of my playing around in Spring Boot and MongoDB + Docker.
Therefore, that means I can follow these steps again later.

So, sorry for most of the parts in this blog post, I can’t explain so much detail.

If I have some time, I will explain about them in the next blog posts.
If you have any questions, don’t hesitate to ask.

And if I understand something wrong, please let me know. 😅

You can feel free to fork or clone this repository.

fResult Sila / Spring Webflux + MongoDB + Docker · GitLab

GitLab.com

gitlab.com

Prerequisite

  • Your favorite IDE (I prefer the IntelliJ)
  • Docker (and Docker Compose)
  • Java (JDK) version 17 or more on your local machine (I use Java 21)
  • Gradle 8

Project Setting & Dependencies

My Configuration for this blog post.
  • Project: Gradle — Kotlin
  • Language: Java
  • Spring Boot Version: 3.x.x (3.0.0 ≤ your_version < 4.0.0)
  • Packaging: Jar
  • Java: 17
  • Dependency: Spring Reactive Web
  • Dependency: Lombok
  • Dependency: Spring Data Reactive MongoDB
  • Dependency: Spring Boot DevTools
  • Dependency: Docker Compose Support

Note:
For Spring Boot version 4 or more may not support for the code in this blog post.

Or download this initial project configuration.

Spring Initializr (My Configuration)

Initializr generates Spring Boot project with just what you need to start quickly!

start.spring.io

Step-by-step

Start the project in Spring Initializr above, then open the project directory by your favorite IDE.

When you open the build.gradle.kts file. You should see it like this.

plugins {
  java
  id("org.springframework.boot") version "3.1.5"
  id("io.spring.dependency-management") version "1.1.3"
}

group = "dev.fresult"
version = "0.0.1"

java {
  sourceCompatibility = JavaVersion.VERSION_17
}

configurations {
  compileOnly {
    extendsFrom(configurations.annotationProcessor.get())
  }
}

repositories {
  mavenCentral()
}

dependencies {
  implementation("org.springframework.boot:spring-boot-starter-data-mongodb-reactive")
  implementation("org.springframework.boot:spring-boot-starter-webflux")
  compileOnly("org.projectlombok:lombok")
  developmentOnly("org.springframework.boot:spring-boot-devtools")
  annotationProcessor("org.projectlombok:lombok")
  testImplementation("org.springframework.boot:spring-boot-starter-test")
  testImplementation("io.projectreactor:reactor-test")
}

tasks.withType<Test> {
  useJUnitPlatform()
}

And then follow these steps

1. Start with the Docker Compose file

Create the compose.dev.yml file in the docker directory then open it.

mkdir docker
# THEN
touch docker/compose.dev.yml
# THEN
open docker/compose.dev.yml

File: /docker/compose.dev.yml

version: "3.8"

services:
  mongodb:
    image: mongo:latest
    container_name: webflux-mongodb
    restart: unless-stopped
    environment:
      - "MONGO_INITDB_DATABASE=my-db"
      - "MONGO_INITDB_ROOT_USERNAME=admin"
      - "MONGO_INITDB_ROOT_PASSWORD=my-password"
    ports:
      - "27777:27017"
    volumes:
      - mongodb:/data/db

volumes:
  mongodb:
    driver: local

2. Create a containerized database

Run this script in your terminal

docker-compose -f docker/compose.dev.yml up -d --build

The terminal should display like this

[+] Running 1/1
 ✔ mongodb Pulled                                                                                                                                                                                                               2.8s 
[+] Building 0.0s (0/0)                                                                                                                                                                                         docker:desktop-linux
[+] Running 1/0
 ✔ Container webflux-mongodb  Running

3. Add the application configuration

Change the file application.properties in the /src/main/resources directory to be application.yml.

Then copy this config below.

File: /src/main/resources/application.yml

server:
  port: 8081

spring:
  data:
    mongodb:
      host: localhost
      port: 27777
      database: ${MONGO_INITDB_ROOT_PASSWORD:my-db}
      username: ${MONGO_INITDB_ROOT_USERNAME}
      password: ${MONGO_INITDB_ROOT_PASSWORD}
      authentication-database: admin

  docker:
    compose:
      file: ./docker/compose.dev.yml
      enabled: true

4. Create the entity (Document) class and repository interface

Car.java
File: /src/main/java/dev/fresult/springreactivemongo/documents/Car.javatouch

@Data
@Document
@RequiredArgsConstructor
public class Car {
  private @Id String id = null;
  private @NonNull String brand;
  private @NonNull String model;
}

CarRepository.java
File: /src/main/java/dev/fresult/springreactivemongo/repositories/CarRepository.java

@Repository
public interface CarRepository extends ReactiveMongoRepository<Car, String> {
  Flux<Car> findByBrandIgnoreCase(String brand);
  Flux<Car> findByModelIgnoreCase(String model);
}

5. Create the service class

CarService.java
File: /src/main/java/dev/fresult/springreactivemongo/services/CarService.java

@Service
@RequiredArgsConstructor
public class CarService {
  private final CarRepository repo;

  public Flux<Car> all() {
    return repo.findAll();
  }

  public Mono<Car> byId(String id) {
    return repo.findById(id);
  }

  public Flux<Car> byBrand(String brand) {
    return repo.findByBrandIgnoreCase(brand);
  }

  public Mono<Car> create(Car car) {
    return repo.save(car);
  }

  public Mono<Car> update(String id, Car car) {
    return createCarMonoOpt(repo.findById(id))
        .flatMap(carOpt -> {
          if (carOpt.isEmpty()) return Mono.empty();

          car.setId(id);
          return repo.save(car);
        });
  }

  public Mono<Void> deleteById(String id) {
    return repo.deleteById(id);
  }

  public Mono<Optional<Car>> createCarMonoOpt(Mono<Car> carMono) {
    return carMono.map(Optional::of).defaultIfEmpty(Optional.empty());
  }
}

6. Create the controller class

CarController.java
File: /src/main/java/dev/fresult/springreactivemongo/controllers/CarController.java

@RestController
@RequestMapping("/cars")
@RequiredArgsConstructor
public class CarController {
  private final CarService service;

  @GetMapping
  public Flux<Car> all(@RequestParam(required = false, value = "brand") Optional<String> brandOpt) {
    if (brandOpt.isEmpty()) return service.all();
    return service.byBrand(brandOpt.get());
  }

  @GetMapping("/{id}")
  public Mono<ResponseEntity<?>> byId(@PathVariable String id) {
    return service.createCarMonoOpt(service.byId(id)).flatMap(flatMapMonoCarOK);
  }

  @PostMapping
  public Mono<ResponseEntity<?>> create(@RequestBody Car car, UriComponentsBuilder uriBuilder) {
    try {
      return service.create(car).flatMap(createdCar -> {
        String location = uriBuilder.path("cars/{id}").buildAndExpand(createdCar.getId()).toUriString();
        return Mono.just(ResponseEntity.created(URI.create(location)).body(createdCar));
      });
    } catch (DecoderException e) {
      System.err.println("error: " + e.getMessage());
      return Mono.just(ResponseEntity.badRequest().body(e.getCause()));
    } catch (Exception e) {
      System.err.println(e.getMessage());
      return Mono.just(ResponseEntity.internalServerError().body(e.getCause()));
    }
  }

  @PutMapping("/{id}")
  public Mono<ResponseEntity<?>> update(@PathVariable String id, @RequestBody Car car) {
    try {
      return service.createCarMonoOpt(service.update(id, car))
          .flatMap(flatMapMonoCarOK);
    } catch (DecoderException e) {
      System.err.println("error: " + e.getMessage());
      return Mono.just(ResponseEntity.badRequest().body(e.getCause()));
    } catch (Exception e) {
      System.err.println(e.getMessage());
      return Mono.just(ResponseEntity.internalServerError().body(e.getCause()));
    }
  }

  @DeleteMapping("/{id}")
  public ResponseEntity<Void> deleteById(@PathVariable String id) {
    service.deleteById(id).subscribe();
    return ResponseEntity.noContent().build();
  }

  private final Function<Optional<Car>, Mono<ResponseEntity<?>>> flatMapMonoCarOK = carOpt ->
      carOpt.<Mono<ResponseEntity<?>>>map(car -> Mono.just(ResponseEntity.ok(car)))
          .orElseGet(() -> Mono.just(ResponseEntity.notFound().build()));
}

6. Prepare API Collection for Postman

Copy this JSON and import it to Postman

{
  "collection": {
    "info": {
      "_postman_id": "b916cc2f-f7fc-47cd-a96b-c7e20abe42eb",
      "name": "WebReactiveMongo",
      "schema": "https://schema.getpostman.com/json/collection/v2.1.0/collection.json",
      "updatedAt": "2023-10-27T07:32:53.000Z",
      "uid": "29603661-b916cc2f-f7fc-47cd-a96b-c7e20abe42eb"
    },
    "item": [
      {
        "name": "All Cars",
        "id": "7be4cd32-13da-43df-8119-899041b809a0",
        "protocolProfileBehavior": {
          "disableBodyPruning": true
        },
        "request": {
          "method": "GET",
          "header": [],
          "url": {
            "raw": "{{base-url}}/cars?brand=honda",
            "host": [
              "{{base-url}}"
            ],
            "path": [
              "cars"
            ],
            "query": [
              {
                "key": "brand",
                "value": "honda"
              }
            ]
          }
        },
        "response": [],
        "uid": "29603661-7be4cd32-13da-43df-8119-899041b809a0"
      },
      {
        "name": "Car By Id",
        "id": "3466933f-9aaa-4933-9358-405f6e07c184",
        "protocolProfileBehavior": {
          "disableBodyPruning": true
        },
        "request": {
          "method": "GET",
          "header": [],
          "url": {
            "raw": "{{base-url}}/cars/:id",
            "host": [
              "{{base-url}}"
            ],
            "path": [
              "cars",
              ":id"
            ],
            "variable": [
              {
                "key": "id",
                "value": "653b50f810597d26ada6624f"
              }
            ]
          }
        },
        "response": [],
        "uid": "29603661-3466933f-9aaa-4933-9358-405f6e07c184"
      },
      {
        "name": "Create",
        "id": "0fc21395-a2b4-469f-a2b5-e072dbab98cd",
        "protocolProfileBehavior": {
          "disableBodyPruning": true
        },
        "request": {
          "method": "POST",
          "header": [],
          "body": {
            "mode": "raw",
            "raw": "{\n    \"brand\": \"Honda\",\n    \"model\": \"Civic\"\n}",
            "options": {
              "raw": {
                "language": "json"
              }
            }
          },
          "url": {
            "raw": "{{base-url}}/cars",
            "host": [
              "{{base-url}}"
            ],
            "path": [
              "cars"
            ]
          }
        },
        "response": [],
        "uid": "29603661-0fc21395-a2b4-469f-a2b5-e072dbab98cd"
      },
      {
        "name": "Update Car by Id",
        "id": "5a5350b8-0062-4bd9-9fad-dfbc7dbd2dcc",
        "protocolProfileBehavior": {
          "disableBodyPruning": true
        },
        "request": {
          "method": "PUT",
          "header": [],
          "body": {
            "mode": "raw",
            "raw": "{\n    \"brand\": \"Honda\",\n    \"model\": \"Civic\"\n}",
            "options": {
              "raw": {
                "language": "json"
              }
            }
          },
          "url": {
            "raw": "{{base-url}}/cars/:id",
            "host": [
              "{{base-url}}"
            ],
            "path": [
              "cars",
              ":id"
            ],
            "variable": [
              {
                "key": "id",
                "value": "653b50f810597d26ada6624f"
              }
            ]
          }
        },
        "response": [],
        "uid": "29603661-5a5350b8-0062-4bd9-9fad-dfbc7dbd2dcc"
      },
      {
        "name": "Delete By Id",
        "id": "f12a6c83-5ba2-45b0-acb6-10d684c6ca20",
        "protocolProfileBehavior": {
          "disableBodyPruning": true
        },
        "request": {
          "method": "DELETE",
          "header": [],
          "url": {
            "raw": "{{base-url}}/cars/:id",
            "host": [
              "{{base-url}}"
            ],
            "path": [
              "cars",
              ":id"
            ],
            "variable": [
              {
                "key": "id",
                "value": "653b6739c05d36108e550f6f",
                "type": "string"
              }
            ]
          }
        },
        "response": [],
        "uid": "29603661-f12a6c83-5ba2-45b0-acb6-10d684c6ca20"
      }
    ]
  }
}

Then prepare the Environment Variable in your Postman.
Set base-url as http://localhost:8081 as below.

7. Test APIs

1. Create 3 cars

2. Get all cars

3. Get cars by brand honda

4. Get the car by ID

Found case: Response 200 OK
Not found case: Response 404 Not found

5. Update the car from Honda City to be Honda Civic.

Success case: Response 200 Success
Not found case: Response 404 Not found

6. Then get all cars again

7. Delete car (Honda Civic)

We will get a response: 204 No content.

8. Get all cars again

The Honda Civic is already gone.

My solution repository.

fResult Sila / Spring Webflux + MongoDB + Docker· GitLab

GitLab.com

gitlab.com

Here is a series of Reactive Programming with Reactor & Spring Boot Webflux (The Road to Backend Developer Edition).

A Series of Reactive Programming with Reactor & Spring Boot Webflux (Road to Backend Developer…

I’m a Frontend Developer who’s enthusiastic about Functional Programming and increasingly curious about Backend…

fresult.medium.com

Check it out and follow me to get an update about it.

Thanks for reading until the final line.
If you’re confused or have any questions, don’t hesitate to leave the comments.

Feel free to connect with me and stay updated on the latest insights and discussions.
👉 https://linkedin.com/in/fResult 👈

Mongodb
Docker Compose
Spring Boot
Reactive Programming
Java

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fResult

Written by fResult

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