springjavaspring reactivefunctional endpointsdockermongoDB

Leveraging Spring Reactive, Functional Endpoints, Docker, and MongoDB

Blocking is a feature of classic servlet-based web frameworks like Spring MVC. Introduced in Spring 5, Spring WebFlux is a reactive framework that operates on servers like Netty and is completely non-blocking. Two programming paradigms are supported by Spring WebFlux. Annotations (Aspect Oriented Programming) and WebFlux.fn (Functional Programming).

Elattar Saad

Thu, 29th February 20244 min read

Leveraging Spring Reactive, Functional Endpoints, Docker, and MongoDB

compose.yaml

services:
  mongodb:
    image: 'mongo:7.0.5'
    environment:
      - 'MONGO_INITDB_DATABASE=songsDB'
      - 'MONGO_INITDB_ROOT_PASSWORD=passw0rd'
      - 'MONGO_INITDB_ROOT_USERNAME=root'
    ports:
      - '27017'

Song.java


import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Getter;
import lombok.Setter;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;

import java.util.UUID;

@Document
@Getter
@Setter
@AllArgsConstructor
@Builder
public class Song {
    @Id
    private UUID id;
    private String title;
    private String artist;
}

SongRepository.java

import org.springframework.data.repository.reactive.ReactiveCrudRepository;
import org.springframework.stereotype.Repository;
import reactor.core.publisher.Flux;

import java.util.UUID;

@Repository
public interface SongRepository extends ReactiveCrudRepository<Song, UUID> {

    Flux<Song> findAllByArtist(final String artist);

}

SongRouterConfig.java

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.reactive.function.server.RouterFunction;
import org.springframework.web.reactive.function.server.ServerResponse;

import static org.springframework.web.reactive.function.server.RouterFunctions.route;

@Configuration
public class SongRouterConfig {

    private final SongHandler handler;

    public SongRouterConfig(SongHandler handler) {
        this.handler = handler;
    }

    @Bean
    public RouterFunction<ServerResponse> router() {
        return route().path("/songs", builder -> builder
                .GET("/artist", handler::findAllByArtist)
                .GET(handler::findAll) // Get endpoints' order is important
                .POST("/new", handler::create)
                .DELETE("/{id}", handler::delete)
        ).build();
    }
}

SongHandler.java

import io.daasrattale.webfluxmongofunctionalendpoints.song.exceptions.InvalidParamException;
import io.daasrattale.webfluxmongofunctionalendpoints.song.exceptions.InvalidUUIDException;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Service;
import org.springframework.web.reactive.function.server.ServerRequest;
import org.springframework.web.reactive.function.server.ServerResponse;
import reactor.core.publisher.Mono;

import java.util.Optional;
import java.util.UUID;

@Service
public class SongHandler {

    private final SongRepository repository;

    public SongHandler(SongRepository repository) {
        this.repository = repository;
    }

    public Mono<ServerResponse> findAll(final ServerRequest request) {
        return ServerResponse
                .ok()
                .body(repository.findAll(), Song.class);
    }

    public Mono<ServerResponse> findAllByArtist(final ServerRequest request) {
        return Mono.just(request.queryParam("artist"))
                .switchIfEmpty(Mono.error(new InvalidParamException("artist")))
                .map(Optional::get)
                .map(repository::findAllByArtist)
                .flatMap(songFlux -> ServerResponse
                        .ok()
                        .body(songFlux, Song.class));
    }

    public Mono<ServerResponse> create(final ServerRequest request) {
        return request.bodyToMono(Song.class)
                .switchIfEmpty(Mono.error(new RuntimeException("Song body not found"))) // you can use that or create a custom exception (recommended)
                .doOnNext(song -> song.setId(UUID.randomUUID()))
                .flatMap(song -> ServerResponse
                        .status(HttpStatus.CREATED)
                        .body(repository.save(song), Song.class)
                );
    }

    public Mono<ServerResponse> delete(final ServerRequest request) {
        return Mono.just(request.pathVariable("id"))
                .map(UUID::fromString)
                .doOnError(throwable -> {
                    throw new InvalidUUIDException(throwable);
                })
                .flatMap(songId -> ServerResponse
                        .ok()
                        .body(repository.deleteById(songId), Void.class)
                );
    }
}

InvalidParamException.java

import lombok.Getter;

@Getter
public class InvalidParamException extends RuntimeException {

    private final String paramName;

    public InvalidParamException(final String paramName) {
        this.paramName = paramName;
    }
}

InvalidUUIDException.java

import lombok.Getter;

@Getter
public class InvalidUUIDException extends RuntimeException {

    private final Throwable cause;

    public InvalidUUIDException(final Throwable cause) {
        this.cause = cause;
    }
}

SongExceptionHandler.java

import io.daasrattale.webfluxmongofunctionalendpoints.song.exceptions.InvalidUUIDException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;

import java.util.Map;

@ControllerAdvice
@Slf4j
public class SongExceptionHandler {


    @ExceptionHandler(InvalidUUIDException.class)
    public ResponseEntity<Map<String, ?>> handle(final InvalidUUIDException exception) {
        return ResponseEntity
                .badRequest()
                .body(
                        Map.of(
                                "status", 400,
                                "message", "Invalid UUID",
                                "details", exception.getCause().getMessage()
                        )
                );
    }

    @ExceptionHandler(Exception.class)
    public ResponseEntity<Map<String, ?>> handle(final Exception exception) {
        log.error("Unhandled Error, message: {}", exception.getMessage());
        return ResponseEntity
                .internalServerError()
                .body(
                        Map.of(
                                "status", 500,
                                "message", "Unknown Error",
                                "details", exception.getMessage()
                        )
                );
    }
}

pom.xml

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb-reactive</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-docker-compose</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

pom.xml

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb-reactive</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</

compose.yaml

services:
  mongodb:
    image: 'mongo:7.0.5'
    environment:
      - 'MONGO_INITDB_DATABASE=songsDB'
      - 'MONGO_INITDB_ROOT_PASSWORD=passw0rd'
      - 'MONGO_INITDB_ROOT_USERNAME=root'
    ports:
      - '27017'

Song.java


import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Getter;
import lombok.Setter;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;

import java.util.UUID;

@Document

SongRepository.java

import org.springframework.data.repository.reactive.ReactiveCrudRepository;
import org.springframework.stereotype.Repository;
import reactor.core.publisher.Flux;

import java.util.UUID;

@Repository
public interface SongRepository extends ReactiveCrudRepository<Song, UUID> {

SongRouterConfig.java

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.reactive.function.server.RouterFunction;
import org.springframework.web.reactive.function.server.ServerResponse;

import static org.springframework.web.reactive.function.server.RouterFunctions.route;

@Configuration
public class SongRouterConfig {

SongHandler.java

import io.daasrattale.webfluxmongofunctionalendpoints.song.exceptions.InvalidParamException;
import io.daasrattale.webfluxmongofunctionalendpoints.song.exceptions.InvalidUUIDException;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Service;
import org.springframework.web.reactive.function.server.ServerRequest;
import org.springframework.web.reactive.function.server.ServerResponse;
import reactor.core.publisher.Mono;

import

InvalidParamException.java

import lombok.Getter;

@Getter
public class InvalidParamException extends RuntimeException {

    private final String paramName;

    public InvalidParamException(final String paramName) {
        this.paramName = paramName;

InvalidUUIDException.java

import lombok.Getter;

@Getter
public class InvalidUUIDException extends RuntimeException {

    private final Throwable cause;

    public InvalidUUIDException(final Throwable cause) {
        this.cause = cause;

SongExceptionHandler.java

import io.daasrattale.webfluxmongofunctionalendpoints.song.exceptions.InvalidUUIDException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;

import java.util.Map;

@ControllerAdvice
@Slf4j

Leveraging Spring Reactive, Functional Endpoints, Docker, and MongoDB

Leveraging Spring Reactive, Functional Endpoints, Docker, and MongoDB

Project Description

Project Dependencies

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Saad Elattar

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