Merge pull request #11078 from anuragkumawat/master

JAVA-2802 - Copied the separate draft code for Mongo DB Reactive Arti…

persistence-modules/pom.xml

@@ -77,6 +77,7 @@
         <module>spring-data-jdbc</module>
         <module>spring-data-keyvalue</module>
         <module>spring-data-mongodb</module>
+        <module>spring-data-mongodb-reactive</module>
         <module>spring-data-neo4j</module>
         <module>spring-data-redis</module>
         <module>spring-data-solr</module>

persistence-modules/spring-data-mongodb-reactive/README.md

@@ -0,0 +1,12 @@
+## Spring Data Reactive Project
+
+This module contains articles about reactive Spring 5 Data
+
+### The Course
+The "REST With Spring" Classes: http://bit.ly/restwithspring
+
+### Relevant Articles
+- [Spring Data Reactive Repositories with MongoDB](https://www.baeldung.com/spring-data-mongodb-reactive)
+- [Spring Data MongoDB Tailable Cursors](https://www.baeldung.com/spring-data-mongodb-tailable-cursors)
+- [A Quick Look at R2DBC with Spring Data](https://www.baeldung.com/spring-data-r2dbc)
+- [Spring Data Reactive Repositories with Couchbase](https://www.baeldung.com/spring-data-reactive-couchbase)

persistence-modules/spring-data-mongodb-reactive/pom.xml

@@ -0,0 +1,157 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="http://maven.apache.org/POM/4.0.0"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>spring-data-mongodb-reactive</artifactId>
+    <name>spring-data-mongodb-reactive</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-2</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-boot-2</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.projectreactor</groupId>
+            <artifactId>reactor-core</artifactId>
+            <version>${reactor-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-couchbase-reactive</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-mongodb-reactive</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.projectreactor</groupId>
+            <artifactId>reactor-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.reactivex.rxjava2</groupId>
+            <artifactId>rxjava</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-test</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>de.flapdoodle.embed</groupId>
+            <artifactId>de.flapdoodle.embed.mongo</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-webflux</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-tx</artifactId>
+            <version>${spring-tx.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.data</groupId>
+            <artifactId>spring-data-r2dbc</artifactId>
+            <version>${spring-data-r2dbc.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.r2dbc</groupId>
+            <artifactId>r2dbc-h2</artifactId>
+            <version>${r2dbc-h2.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <version>${h2.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.httpcomponents</groupId>
+            <artifactId>httpclient</artifactId>
+            <version>${httpclient.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.couchbase.mock</groupId>
+            <artifactId>CouchbaseMock</artifactId>
+            <version>${couchbaseMock.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>${java.version}</source>
+                    <target>${java.version}</target>
+                </configuration>
+                <executions>
+                    <!-- Replacing default-compile as it is treated specially by maven -->
+                    <execution>
+                        <id>default-compile</id>
+                        <phase>none</phase>
+                    </execution>
+                    <!-- Replacing default-testCompile as it is treated specially by maven -->
+                    <execution>
+                        <id>default-testCompile</id>
+                        <phase>none</phase>
+                    </execution>
+                    <execution>
+                        <id>java-compile</id>
+                        <phase>compile</phase>
+                        <goals>
+                            <goal>compile</goal>
+                        </goals>
+                    </execution>
+                    <execution>
+                        <id>java-test-compile</id>
+                        <phase>test-compile</phase>
+                        <goals>
+                            <goal>testCompile</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <spring-tx.version>5.2.2.RELEASE</spring-tx.version>
+        <spring-data-r2dbc.version>1.0.0.RELEASE</spring-data-r2dbc.version>
+        <r2dbc-h2.version>0.8.1.RELEASE</r2dbc-h2.version>
+        <httpclient.version>4.5.2</httpclient.version>
+        <h2.version>1.4.200</h2.version>
+        <couchbaseMock.version>1.5.23</couchbaseMock.version>
+        <reactor-core.version>3.3.1.RELEASE</reactor-core.version>
+        <!-- 
+        	This spring-boot.version is set manually, 
+        	For upgrading this please refer http://team.baeldung.com/browse/JAVA-2802 
+        -->
+        <spring-boot.version>2.2.6.RELEASE</spring-boot.version>
+    </properties>
+
+</project>

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/couchbase/ReactiveCouchbaseApplication.java

@@ -0,0 +1,13 @@
+package com.baeldung.couchbase;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration;
+
+@SpringBootApplication(exclude = MongoAutoConfiguration.class)
+public class ReactiveCouchbaseApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(ReactiveCouchbaseApplication.class, args);
+    }
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/couchbase/configuration/CouchbaseProperties.java

@@ -0,0 +1,43 @@
+package com.baeldung.couchbase.configuration;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.PropertySource;
+
+import java.util.Collections;
+import java.util.List;
+
+@Configuration
+@PropertySource("classpath:couchbase.properties")
+public class CouchbaseProperties {
+
+    private final List<String> bootstrapHosts;
+    private final String bucketName;
+    private final String bucketPassword;
+    private final int port;
+
+    public CouchbaseProperties(@Value("${spring.couchbase.bootstrap-hosts}") final List<String> bootstrapHosts, @Value("${spring.couchbase.bucket.name}") final String bucketName, @Value("${spring.couchbase.bucket.password}") final String bucketPassword,
+      @Value("${spring.couchbase.port}") final int port) {
+        this.bootstrapHosts = Collections.unmodifiableList(bootstrapHosts);
+        this.bucketName = bucketName;
+        this.bucketPassword = bucketPassword;
+        this.port = port;
+    }
+
+    public List<String> getBootstrapHosts() {
+        return bootstrapHosts;
+    }
+
+    public String getBucketName() {
+        return bucketName;
+    }
+
+    public String getBucketPassword() {
+        return bucketPassword;
+    }
+
+    public int getPort() {
+        return port;
+    }
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/couchbase/configuration/N1QLReactiveCouchbaseConfiguration.java

@@ -0,0 +1,15 @@
+package com.baeldung.couchbase.configuration;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Primary;
+import org.springframework.data.couchbase.repository.config.EnableReactiveCouchbaseRepositories;
+
+@Configuration
+@EnableReactiveCouchbaseRepositories("com.baeldung.couchbase.domain.repository.n1ql")
+@Primary
+public class N1QLReactiveCouchbaseConfiguration extends ReactiveCouchbaseConfiguration {
+
+    public N1QLReactiveCouchbaseConfiguration(CouchbaseProperties couchbaseProperties) {
+        super(couchbaseProperties);
+    }
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/couchbase/configuration/ReactiveCouchbaseConfiguration.java

@@ -0,0 +1,48 @@
+package com.baeldung.couchbase.configuration;
+
+import com.couchbase.client.java.env.CouchbaseEnvironment;
+import com.couchbase.client.java.env.DefaultCouchbaseEnvironment;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.data.couchbase.config.AbstractReactiveCouchbaseConfiguration;
+import org.springframework.data.couchbase.config.BeanNames;
+import org.springframework.data.couchbase.repository.support.IndexManager;
+
+import java.util.List;
+
+public abstract class ReactiveCouchbaseConfiguration extends AbstractReactiveCouchbaseConfiguration {
+
+    private CouchbaseProperties couchbaseProperties;
+
+    public ReactiveCouchbaseConfiguration(final CouchbaseProperties couchbaseProperties) {
+        this.couchbaseProperties = couchbaseProperties;
+    }
+
+    @Override
+    protected List<String> getBootstrapHosts() {
+        return couchbaseProperties.getBootstrapHosts();
+    }
+
+    @Override
+    protected String getBucketName() {
+        return couchbaseProperties.getBucketName();
+    }
+
+    @Override
+    protected String getBucketPassword() {
+        return couchbaseProperties.getBucketPassword();
+    }
+
+    @Override
+    public CouchbaseEnvironment couchbaseEnvironment() {
+        return DefaultCouchbaseEnvironment
+          .builder()
+          .bootstrapHttpDirectPort(couchbaseProperties.getPort())
+          .build();
+    }
+    
+    @Bean(name = BeanNames.COUCHBASE_INDEX_MANAGER)
+    public IndexManager couchbaseIndexManager() {
+        return new IndexManager(true, true, false);
+    }
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/couchbase/configuration/ViewReactiveCouchbaseConfiguration.java

@@ -0,0 +1,13 @@
+package com.baeldung.couchbase.configuration;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.couchbase.repository.config.EnableReactiveCouchbaseRepositories;
+
+@Configuration
+@EnableReactiveCouchbaseRepositories("com.baeldung.couchbase.domain.repository.view")
+public class ViewReactiveCouchbaseConfiguration extends ReactiveCouchbaseConfiguration {
+
+    public ViewReactiveCouchbaseConfiguration(CouchbaseProperties couchbaseProperties) {
+        super(couchbaseProperties);
+    }
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/couchbase/domain/Person.java

@@ -0,0 +1,43 @@
+package com.baeldung.couchbase.domain;
+
+import org.springframework.data.annotation.Id;
+import org.springframework.data.couchbase.core.mapping.Document;
+
+import java.util.Objects;
+import java.util.UUID;
+
+@Document
+public class Person {
+
+    @Id private UUID id;
+    private String firstName;
+
+    public Person(final UUID id, final String firstName) {
+        this.id = id;
+        this.firstName = firstName;
+    }
+
+    private Person() {
+    }
+
+    public UUID getId() {
+        return id;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Person person = (Person) o;
+        return Objects.equals(id, person.id) && Objects.equals(firstName, person.firstName);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, firstName);
+    }
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/couchbase/domain/repository/n1ql/N1QLPersonRepository.java

@@ -0,0 +1,16 @@
+package com.baeldung.couchbase.domain.repository.n1ql;
+
+import com.baeldung.couchbase.domain.Person;
+import org.springframework.data.couchbase.core.query.N1qlPrimaryIndexed;
+import org.springframework.data.repository.reactive.ReactiveCrudRepository;
+import org.springframework.stereotype.Repository;
+import reactor.core.publisher.Flux;
+
+import java.util.UUID;
+
+@Repository
+@N1qlPrimaryIndexed
+public interface N1QLPersonRepository extends ReactiveCrudRepository<Person, UUID> {
+
+    Flux<Person> findAllByFirstName(final String firstName);
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/couchbase/domain/repository/n1ql/N1QLSortingPersonRepository.java

@@ -0,0 +1,13 @@
+package com.baeldung.couchbase.domain.repository.n1ql;
+
+import com.baeldung.couchbase.domain.Person;
+import org.springframework.data.couchbase.core.query.N1qlPrimaryIndexed;
+import org.springframework.data.repository.reactive.ReactiveSortingRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.UUID;
+
+@Repository
+@N1qlPrimaryIndexed
+public interface N1QLSortingPersonRepository extends ReactiveSortingRepository<Person, UUID> {
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/couchbase/domain/repository/view/ViewPersonRepository.java

@@ -0,0 +1,20 @@
+package com.baeldung.couchbase.domain.repository.view;
+
+import com.baeldung.couchbase.domain.Person;
+import org.springframework.data.couchbase.core.query.View;
+import org.springframework.data.couchbase.core.query.ViewIndexed;
+import org.springframework.data.repository.reactive.ReactiveCrudRepository;
+import org.springframework.stereotype.Repository;
+import reactor.core.publisher.Flux;
+
+import java.util.UUID;
+
+@Repository
+@ViewIndexed(designDoc = ViewPersonRepository.DESIGN_DOCUMENT)
+public interface ViewPersonRepository extends ReactiveCrudRepository<Person, UUID> {
+
+    String DESIGN_DOCUMENT = "person";
+
+    @View(designDocument = ViewPersonRepository.DESIGN_DOCUMENT)
+    Flux<Person> findByFirstName(String firstName);
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/r2dbc/R2dbcApplication.java

@@ -0,0 +1,15 @@
+package com.baeldung.r2dbc;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.ComponentScan;
+
+@SpringBootApplication
+@ComponentScan(basePackages = "com.baeldung.r2dbc")
+public class R2dbcApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(R2dbcApplication.class, args);
+    }
+
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/r2dbc/configuration/R2DBCConfiguration.java

@@ -0,0 +1,21 @@
+package com.baeldung.r2dbc.configuration;
+
+import io.r2dbc.h2.H2ConnectionConfiguration;
+import io.r2dbc.h2.H2ConnectionFactory;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.r2dbc.config.AbstractR2dbcConfiguration;
+import org.springframework.data.r2dbc.repository.config.EnableR2dbcRepositories;
+
+@Configuration
+@EnableR2dbcRepositories(basePackages = "com.baeldung.r2dbc.repository")
+public class R2DBCConfiguration extends AbstractR2dbcConfiguration {
+    @Bean
+    public H2ConnectionFactory connectionFactory() {
+        return new H2ConnectionFactory(
+                H2ConnectionConfiguration.builder()
+                        .url("mem:testdb;DB_CLOSE_DELAY=-1;TRACE_LEVEL_FILE=4")
+                        .username("sa")
+                        .build());
+    }
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/r2dbc/model/Player.java

@@ -0,0 +1,18 @@
+package com.baeldung.r2dbc.model;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+import org.springframework.data.annotation.Id;
+import org.springframework.data.relational.core.mapping.Table;
+
+@Data
+@NoArgsConstructor
+@AllArgsConstructor
+@Table
+public class Player {
+    @Id
+    Integer id;
+    String name;
+    Integer age;
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/r2dbc/repository/PlayerRepository.java

@@ -0,0 +1,17 @@
+package com.baeldung.r2dbc.repository;
+
+import org.springframework.data.r2dbc.repository.Query;
+import org.springframework.data.repository.reactive.ReactiveCrudRepository;
+
+import com.baeldung.r2dbc.model.Player;
+
+import reactor.core.publisher.Flux;
+
+public interface PlayerRepository extends ReactiveCrudRepository<Player, Integer> {
+
+    @Query("select id, name, age from player where name = $1")
+    Flux<Player> findAllByName(String name);
+
+    @Query("select * from player where age = $1")
+    Flux<Player> findByAge(int age);
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/reactive/Spring5ReactiveApplication.java

@@ -0,0 +1,25 @@
+package com.baeldung.reactive;
+
+import com.mongodb.reactivestreams.client.MongoClient;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+import org.springframework.data.mongodb.core.ReactiveMongoTemplate;
+
+@SpringBootApplication
+public class Spring5ReactiveApplication{
+
+    public static void main(String[] args) {
+        SpringApplication.run(Spring5ReactiveApplication.class, args);
+    }
+
+    @Autowired
+    MongoClient mongoClient;
+
+    @Bean
+    public ReactiveMongoTemplate reactiveMongoTemplate() {
+        return new ReactiveMongoTemplate(mongoClient, "test");
+    }
+
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/reactive/model/Account.java

@@ -0,0 +1,21 @@
+package com.baeldung.reactive.model;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+import lombok.ToString;
+import org.springframework.data.annotation.Id;
+import org.springframework.data.mongodb.core.mapping.Document;
+
+@Document
+@Data
+@ToString
+@AllArgsConstructor
+@NoArgsConstructor
+public class Account {
+
+    @Id
+    private String id;
+    private String owner;
+    private Double value;
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/reactive/repository/AccountCrudRepository.java

@@ -0,0 +1,15 @@
+package com.baeldung.reactive.repository;
+
+import com.baeldung.reactive.model.Account;
+import org.springframework.data.repository.reactive.ReactiveCrudRepository;
+import org.springframework.stereotype.Repository;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+@Repository
+public interface AccountCrudRepository extends ReactiveCrudRepository<Account, String> {
+
+    public Flux<Account> findAllByValue(Double value);
+
+    public Mono<Account> findFirstByOwner(Mono<String> owner);
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/reactive/repository/AccountMongoRepository.java

@@ -0,0 +1,7 @@
+package com.baeldung.reactive.repository;
+
+import com.baeldung.reactive.model.Account;
+import org.springframework.data.mongodb.repository.ReactiveMongoRepository;
+
+public interface AccountMongoRepository extends ReactiveMongoRepository<Account, String> {
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/reactive/repository/AccountRxJavaRepository.java

@@ -0,0 +1,15 @@
+package com.baeldung.reactive.repository;
+
+import com.baeldung.reactive.model.Account;
+import io.reactivex.Observable;
+import io.reactivex.Single;
+import org.springframework.data.repository.reactive.RxJava2CrudRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface AccountRxJavaRepository extends RxJava2CrudRepository<Account, String>{
+
+    public Observable<Account> findAllByValue(Double value);
+
+    public Single<Account> findFirstByOwner(Single<String> owner);
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/reactive/template/AccountTemplateOperations.java

@@ -0,0 +1,33 @@
+package com.baeldung.reactive.template;
+
+import com.baeldung.reactive.model.Account;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.data.mongodb.core.ReactiveMongoTemplate;
+import org.springframework.data.mongodb.core.ReactiveRemoveOperation;
+import org.springframework.stereotype.Service;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+@Service
+public class AccountTemplateOperations {
+
+    @Autowired
+    ReactiveMongoTemplate template;
+
+    public Mono<Account> findById(String id) {
+        return template.findById(id, Account.class);
+    }
+
+    public Flux<Account> findAll() {
+        return template.findAll(Account.class);
+    }
+
+    public Mono<Account> save(Mono<Account> account) {
+        return template.save(account);
+    }
+
+    public ReactiveRemoveOperation.ReactiveRemove<Account> deleteAll() {
+        return template.remove(Account.class);
+    }
+
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/tailablecursor/LogsCounterApplication.java

@@ -0,0 +1,11 @@
+package com.baeldung.tailablecursor;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class LogsCounterApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(LogsCounterApplication.class, args);
+    }
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/tailablecursor/domain/Log.java

@@ -0,0 +1,21 @@
+package com.baeldung.tailablecursor.domain;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+import org.springframework.data.annotation.Id;
+import org.springframework.data.mongodb.core.mapping.Document;
+
+@Data
+@Document
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class Log {
+    @Id
+    private String id;
+    private String service;
+    private LogLevel level;
+    private String message;
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/tailablecursor/domain/LogLevel.java

@@ -0,0 +1,5 @@
+package com.baeldung.tailablecursor.domain;
+
+public enum LogLevel {
+    ERROR, WARN, INFO
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/tailablecursor/repository/LogsRepository.java

@@ -0,0 +1,12 @@
+package com.baeldung.tailablecursor.repository;
+
+import com.baeldung.tailablecursor.domain.Log;
+import com.baeldung.tailablecursor.domain.LogLevel;
+import org.springframework.data.mongodb.repository.Tailable;
+import org.springframework.data.repository.reactive.ReactiveCrudRepository;
+import reactor.core.publisher.Flux;
+
+public interface LogsRepository extends ReactiveCrudRepository<Log, String> {
+    @Tailable
+    Flux<Log> findByLevel(LogLevel level);
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/tailablecursor/service/ErrorLogsCounter.java

@@ -0,0 +1,62 @@
+package com.baeldung.tailablecursor.service;
+
+import com.baeldung.tailablecursor.domain.Log;
+import com.baeldung.tailablecursor.domain.LogLevel;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.mongodb.core.MongoTemplate;
+import org.springframework.data.mongodb.core.mapping.Document;
+import org.springframework.data.mongodb.core.messaging.DefaultMessageListenerContainer;
+import org.springframework.data.mongodb.core.messaging.MessageListener;
+import org.springframework.data.mongodb.core.messaging.MessageListenerContainer;
+import org.springframework.data.mongodb.core.messaging.TailableCursorRequest;
+
+import javax.annotation.PreDestroy;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.springframework.data.mongodb.core.query.Criteria.where;
+import static org.springframework.data.mongodb.core.query.Query.query;
+
+@Slf4j
+public class ErrorLogsCounter implements LogsCounter {
+
+    private static final String LEVEL_FIELD_NAME = "level";
+
+    private final String collectionName;
+    private final MessageListenerContainer container;
+
+    private final AtomicInteger counter = new AtomicInteger();
+
+    public ErrorLogsCounter(MongoTemplate mongoTemplate,
+                            String collectionName) {
+        this.collectionName = collectionName;
+        this.container = new DefaultMessageListenerContainer(mongoTemplate);
+
+        container.start();
+        TailableCursorRequest<Log> request = getTailableCursorRequest();
+        container.register(request, Log.class);
+    }
+
+    @SuppressWarnings("unchecked")
+    private TailableCursorRequest<Log> getTailableCursorRequest() {
+        MessageListener<Document, Log> listener = message -> {
+          log.info("ERROR log received: {}", message.getBody());
+          counter.incrementAndGet();
+        };
+
+        return TailableCursorRequest.builder()
+          .collection(collectionName)
+          .filter(query(where(LEVEL_FIELD_NAME).is(LogLevel.ERROR)))
+          .publishTo(listener)
+          .build();
+    }
+
+    @Override
+    public int count() {
+        return counter.get();
+    }
+
+    @PreDestroy
+    public void close() {
+        container.stop();
+    }
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/tailablecursor/service/InfoLogsCounter.java

@@ -0,0 +1,36 @@
+package com.baeldung.tailablecursor.service;
+
+import com.baeldung.tailablecursor.domain.Log;
+import com.baeldung.tailablecursor.domain.LogLevel;
+import com.baeldung.tailablecursor.repository.LogsRepository;
+import lombok.extern.slf4j.Slf4j;
+import reactor.core.Disposable;
+import reactor.core.publisher.Flux;
+
+import javax.annotation.PreDestroy;
+import java.util.concurrent.atomic.AtomicInteger;
+
+@Slf4j
+public class InfoLogsCounter implements LogsCounter {
+
+    private final AtomicInteger counter = new AtomicInteger();
+    private final Disposable subscription;
+
+    public InfoLogsCounter(LogsRepository repository) {
+        Flux<Log> stream = repository.findByLevel(LogLevel.INFO);
+        this.subscription = stream.subscribe(logEntity -> {
+          log.info("INFO log received: " + logEntity);
+          counter.incrementAndGet();
+        });
+    }
+
+    @Override
+    public int count() {
+        return this.counter.get();
+    }
+
+    @PreDestroy
+    public void close() {
+        this.subscription.dispose();
+    }
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/tailablecursor/service/LogsCounter.java

@@ -0,0 +1,5 @@
+package com.baeldung.tailablecursor.service;
+
+public interface LogsCounter {
+    int count();
+}

persistence-modules/spring-data-mongodb-reactive/src/main/java/com/baeldung/tailablecursor/service/WarnLogsCounter.java

@@ -0,0 +1,41 @@
+package com.baeldung.tailablecursor.service;
+
+import com.baeldung.tailablecursor.domain.Log;
+import com.baeldung.tailablecursor.domain.LogLevel;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.mongodb.core.ReactiveMongoOperations;
+import reactor.core.Disposable;
+import reactor.core.publisher.Flux;
+
+import javax.annotation.PreDestroy;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.springframework.data.mongodb.core.query.Criteria.where;
+import static org.springframework.data.mongodb.core.query.Query.query;
+
+@Slf4j
+public class WarnLogsCounter implements LogsCounter {
+
+    private static final String LEVEL_FIELD_NAME = "level";
+
+    private final AtomicInteger counter = new AtomicInteger();
+    private final Disposable subscription;
+
+    public WarnLogsCounter(ReactiveMongoOperations template) {
+        Flux<Log> stream = template.tail(query(where(LEVEL_FIELD_NAME).is(LogLevel.WARN)), Log.class);
+        subscription = stream.subscribe(logEntity -> {
+          log.warn("WARN log received: " + logEntity);
+          counter.incrementAndGet();
+        });
+    }
+
+    @Override
+    public int count() {
+        return counter.get();
+    }
+
+    @PreDestroy
+    public void close() {
+        subscription.dispose();
+    }
+}