aggregation operations examples with mongoDB webflux

.gitignore

+HELP.md
+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/

.mvn/wrapper/maven-wrapper.properties

+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.8.6/apache-maven-3.8.6-bin.zip
+wrapperUrl=https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar

mvnw.cmd

+@REM ----------------------------------------------------------------------------
+@REM Licensed to the Apache Software Foundation (ASF) under one
+@REM or more contributor license agreements.  See the NOTICE file
+@REM distributed with this work for additional information
+@REM regarding copyright ownership.  The ASF licenses this file
+@REM to you under the Apache License, Version 2.0 (the
+@REM "License"); you may not use this file except in compliance
+@REM with the License.  You may obtain a copy of the License at
+@REM
+@REM    https://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM Unless required by applicable law or agreed to in writing,
+@REM software distributed under the License is distributed on an
+@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+@REM KIND, either express or implied.  See the License for the
+@REM specific language governing permissions and limitations
+@REM under the License.
+@REM ----------------------------------------------------------------------------
+
+@REM ----------------------------------------------------------------------------
+@REM Maven Start Up Batch script
+@REM
+@REM Required ENV vars:
+@REM JAVA_HOME - location of a JDK home dir
+@REM
+@REM Optional ENV vars
+@REM M2_HOME - location of maven2's installed home dir
+@REM MAVEN_BATCH_ECHO - set to 'on' to enable the echoing of the batch commands
+@REM MAVEN_BATCH_PAUSE - set to 'on' to wait for a keystroke before ending
+@REM MAVEN_OPTS - parameters passed to the Java VM when running Maven
+@REM     e.g. to debug Maven itself, use
+@REM set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+@REM MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+@REM ----------------------------------------------------------------------------
+
+@REM Begin all REM lines with '@' in case MAVEN_BATCH_ECHO is 'on'
+@echo off
+@REM set title of command window
+title %0
+@REM enable echoing by setting MAVEN_BATCH_ECHO to 'on'
+@if "%MAVEN_BATCH_ECHO%" == "on"  echo %MAVEN_BATCH_ECHO%
+
+@REM set %HOME% to equivalent of $HOME
+if "%HOME%" == "" (set "HOME=%HOMEDRIVE%%HOMEPATH%")
+
+@REM Execute a user defined script before this one
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPre
+@REM check for pre script, once with legacy .bat ending and once with .cmd ending
+if exist "%USERPROFILE%\mavenrc_pre.bat" call "%USERPROFILE%\mavenrc_pre.bat" %*
+if exist "%USERPROFILE%\mavenrc_pre.cmd" call "%USERPROFILE%\mavenrc_pre.cmd" %*
+:skipRcPre
+
+@setlocal
+
+set ERROR_CODE=0
+
+@REM To isolate internal variables from possible post scripts, we use another setlocal
+@setlocal
+
+@REM ==== START VALIDATION ====
+if not "%JAVA_HOME%" == "" goto OkJHome
+
+echo.
+echo Error: JAVA_HOME not found in your environment. >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+:OkJHome
+if exist "%JAVA_HOME%\bin\java.exe" goto init
+
+echo.
+echo Error: JAVA_HOME is set to an invalid directory. >&2
+echo JAVA_HOME = "%JAVA_HOME%" >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+@REM ==== END VALIDATION ====
+
+:init
+
+@REM Find the project base dir, i.e. the directory that contains the folder ".mvn".
+@REM Fallback to current working directory if not found.
+
+set MAVEN_PROJECTBASEDIR=%MAVEN_BASEDIR%
+IF NOT "%MAVEN_PROJECTBASEDIR%"=="" goto endDetectBaseDir
+
+set EXEC_DIR=%CD%
+set WDIR=%EXEC_DIR%
+:findBaseDir
+IF EXIST "%WDIR%"\.mvn goto baseDirFound
+cd ..
+IF "%WDIR%"=="%CD%" goto baseDirNotFound
+set WDIR=%CD%
+goto findBaseDir
+
+:baseDirFound
+set MAVEN_PROJECTBASEDIR=%WDIR%
+cd "%EXEC_DIR%"
+goto endDetectBaseDir
+
+:baseDirNotFound
+set MAVEN_PROJECTBASEDIR=%EXEC_DIR%
+cd "%EXEC_DIR%"
+
+:endDetectBaseDir
+
+IF NOT EXIST "%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config" goto endReadAdditionalConfig
+
+@setlocal EnableExtensions EnableDelayedExpansion
+for /F "usebackq delims=" %%a in ("%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config") do set JVM_CONFIG_MAVEN_PROPS=!JVM_CONFIG_MAVEN_PROPS! %%a
+@endlocal & set JVM_CONFIG_MAVEN_PROPS=%JVM_CONFIG_MAVEN_PROPS%
+
+:endReadAdditionalConfig
+
+SET MAVEN_JAVA_EXE="%JAVA_HOME%\bin\java.exe"
+set WRAPPER_JAR="%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.jar"
+set WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+set DOWNLOAD_URL="https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar"
+
+FOR /F "usebackq tokens=1,2 delims==" %%A IN ("%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.properties") DO (
+    IF "%%A"=="wrapperUrl" SET DOWNLOAD_URL=%%B
+)
+
+@REM Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+@REM This allows using the maven wrapper in projects that prohibit checking in binary data.
+if exist %WRAPPER_JAR% (
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Found %WRAPPER_JAR%
+    )
+) else (
+    if not "%MVNW_REPOURL%" == "" (
+        SET DOWNLOAD_URL="%MVNW_REPOURL%/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar"
+    )
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Couldn't find %WRAPPER_JAR%, downloading it ...
+        echo Downloading from: %DOWNLOAD_URL%
+    )
+
+    powershell -Command "&{"^
+		"$webclient = new-object System.Net.WebClient;"^
+		"if (-not ([string]::IsNullOrEmpty('%MVNW_USERNAME%') -and [string]::IsNullOrEmpty('%MVNW_PASSWORD%'))) {"^
+		"$webclient.Credentials = new-object System.Net.NetworkCredential('%MVNW_USERNAME%', '%MVNW_PASSWORD%');"^
+		"}"^
+		"[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; $webclient.DownloadFile('%DOWNLOAD_URL%', '%WRAPPER_JAR%')"^
+		"}"
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Finished downloading %WRAPPER_JAR%
+    )
+)
+@REM End of extension
+
+@REM Provide a "standardized" way to retrieve the CLI args that will
+@REM work with both Windows and non-Windows executions.
+set MAVEN_CMD_LINE_ARGS=%*
+
+%MAVEN_JAVA_EXE% ^
+  %JVM_CONFIG_MAVEN_PROPS% ^
+  %MAVEN_OPTS% ^
+  %MAVEN_DEBUG_OPTS% ^
+  -classpath %WRAPPER_JAR% ^
+  "-Dmaven.multiModuleProjectDirectory=%MAVEN_PROJECTBASEDIR%" ^
+  %WRAPPER_LAUNCHER% %MAVEN_CONFIG% %*
+if ERRORLEVEL 1 goto error
+goto end
+
+:error
+set ERROR_CODE=1
+
+:end
+@endlocal & set ERROR_CODE=%ERROR_CODE%
+
+if not "%MAVEN_SKIP_RC%"=="" goto skipRcPost
+@REM check for post script, once with legacy .bat ending and once with .cmd ending
+if exist "%USERPROFILE%\mavenrc_post.bat" call "%USERPROFILE%\mavenrc_post.bat"
+if exist "%USERPROFILE%\mavenrc_post.cmd" call "%USERPROFILE%\mavenrc_post.cmd"
+:skipRcPost
+
+@REM pause the script if MAVEN_BATCH_PAUSE is set to 'on'
+if "%MAVEN_BATCH_PAUSE%"=="on" pause
+
+if "%MAVEN_TERMINATE_CMD%"=="on" exit %ERROR_CODE%
+
+cmd /C exit /B %ERROR_CODE%

pom.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>3.0.1</version>
+		<relativePath/> <!-- lookup parent from repository -->
+	</parent>
+	<groupId>com.example</groupId>
+	<artifactId>demo</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<name>demo</name>
+	<description>Demo project for Spring Boot</description>
+	<properties>
+		<java.version>11</java.version>
+	</properties>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-webflux</artifactId>
+		</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>
+
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-mongodb-reactive</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.projectlombok</groupId>
+			<artifactId>lombok</artifactId>
+			<optional>true</optional>
+		</dependency>
+
+		<dependency>
+			<groupId>javax.xml.bind</groupId>
+			<artifactId>jaxb-api</artifactId>
+			<version>2.3.0</version>
+		</dependency>
+		<dependency>
+			<groupId>javax.servlet</groupId>
+			<artifactId>javax.servlet-api</artifactId>
+			<version>3.1.0</version>
+			<scope>provided</scope>
+		</dependency>
+
+
+		<dependency>
+			<groupId>org.springframework.data</groupId>
+			<artifactId>spring-data-mongodb</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.mongodb</groupId>
+			<artifactId>mongodb-driver-reactivestreams</artifactId>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>

src/main/java/com/example/demo/DemoApplication.java

+package com.example.demo;
+
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.autoconfigure.domain.EntityScan;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.data.mongodb.repository.config.EnableReactiveMongoRepositories;
+import org.springframework.web.reactive.config.EnableWebFlux;
+
+@SpringBootApplication
+@ComponentScan({"com.example"})
+@EntityScan("com.example.demo")
+@EnableReactiveMongoRepositories(basePackages = "com.example")
+@Slf4j
+public class DemoApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(DemoApplication.class, args);
+	}
+
+}

src/main/java/com/example/demo/config/MongoDbConfig.java

+package com.example.demo.config;
+
+import com.mongodb.reactivestreams.client.MongoClient;
+import com.mongodb.reactivestreams.client.MongoClients;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.autoconfigure.mongo.ReactiveMongoClientFactory;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.mongodb.config.AbstractReactiveMongoConfiguration;
+import org.springframework.data.mongodb.core.ReactiveMongoTemplate;
+import org.springframework.data.mongodb.repository.config.EnableReactiveMongoRepositories;
+
+@Configuration
+@EnableReactiveMongoRepositories(basePackages = " com.example")
+public class MongoDbConfig extends AbstractReactiveMongoConfiguration {
+
+    @Value("${dbname}")
+    private String dbname;
+
+    @Value("${dbport}")
+    private String dbport;
+
+
+    @Override
+    public MongoClient reactiveMongoClient() {
+        return MongoClients.create();
+    }
+    @Override
+    protected String getDatabaseName() {
+        return dbname ;
+    }
+    @Bean
+    public ReactiveMongoTemplate reactiveMongoTemplate(){
+        return new ReactiveMongoTemplate(reactiveMongoClient(),getDatabaseName());
+    }
+}

src/main/java/com/example/demo/config/webFluxConfig.java

+package com.example.demo.config;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.reactive.config.EnableWebFlux;
+import org.springframework.web.reactive.config.WebFluxConfigurer;
+
+
+@Configuration
+@EnableWebFlux
+public class webFluxConfig implements WebFluxConfigurer {
+}

src/main/java/com/example/demo/controller/EmployeeController.java

+package com.example.demo.controller;
+
+import com.example.demo.exceptions.EmployeeNotFoundException;
+import com.example.demo.model.Employee;
+import com.example.demo.service.EmployeeServiceImpl;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.util.StringUtils;
+import org.springframework.web.bind.annotation.*;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+@RestController
+@RequestMapping("/employee")
+@Slf4j
+public class EmployeeController {
+
+    @Autowired
+    private EmployeeServiceImpl employeeService;
+
+
+    @PostMapping("/create/emp")
+    @ResponseStatus(HttpStatus.CREATED)
+    public void createEmp(@RequestBody Employee employee) {
+      employeeService.createEmp(employee);
+    }
+    @GetMapping(value = { "/all"},produces = MediaType.TEXT_EVENT_STREAM_VALUE)
+    public ResponseEntity<Flux<Employee>> getAllEmployees(){
+        return ResponseEntity.ok().body(employeeService.findAll());
+    }
+
+
+    @GetMapping(value = { "/{id}"},produces = MediaType.TEXT_EVENT_STREAM_VALUE)
+    public ResponseEntity<Mono<Employee>> getEmployeeById(@PathVariable("id") Integer id){
+
+        return ResponseEntity.ok().body(employeeService.findEmployeeById(id));
+    }
+
+
+    @GetMapping(value = { "/findallempbyrole"})
+    public Flux<Employee> getAllEmpbyRole(){
+        return employeeService.findAllEmpBySal();
+    }
+
+
+    @PutMapping(value = { "/update"})
+    public Mono<Employee> updateEmployee(@RequestBody Employee employee){
+       return employeeService.updateEmployee(employee);
+    }
+    @PutMapping(value = { "/update/{id}"})
+    public Mono<Employee> updateEmployeeById(@PathVariable("id") Integer id,
+                                             @RequestParam("name") String name){
+        if (name.isEmpty()) {
+            throw new EmployeeNotFoundException("Name cant be Empty");
+        }
+            return employeeService.updateEmployeeById(id, name);
+    }
+
+
+    @PutMapping(value = { "/updateemployeebysal"})
+    public Flux<Employee> updateEmployeeBySal(@RequestParam("sal") Integer sal,
+                                              @RequestParam("role") String role){
+      /*  if (StringUtils.isEmpty(sal)) {
+            throw new EmployeeNotFoundException("Name cant be Empty");
+        }*/
+        log.info("in update employee by salary ");
+        return employeeService.updateEmployeeBySal(sal, role);
+
+    }
+
+
+
+}

src/main/java/com/example/demo/controller/ExceptionController.java

+package com.example.demo.controller;
+
+import com.example.demo.exceptions.EmployeeNotFoundException;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.bind.annotation.RestControllerAdvice;
+
+@RestControllerAdvice
+@ResponseStatus(value = HttpStatus.BAD_REQUEST)
+public class ExceptionController {
+
+   @ExceptionHandler(EmployeeNotFoundException.class)
+    public ResponseEntity<String> EmployeeNotFoundException(EmployeeNotFoundException e){
+       return ResponseEntity.status(HttpStatus.NOT_FOUND).body(e.getMessage());
+   }
+
+    @ExceptionHandler(Exception.class)
+    public ResponseEntity<String> globalException(Exception e){
+        return ResponseEntity.status(HttpStatus.NOT_FOUND).body(e.getMessage());
+    }
+}

src/main/java/com/example/demo/exceptions/EmployeeNotFoundException.java

+package com.example.demo.exceptions;
+
+public class EmployeeNotFoundException extends RuntimeException{
+
+    public EmployeeNotFoundException(String message){
+        super(message);
+    }
+}

src/main/java/com/example/demo/model/Address.java

+package com.example.demo.model;
+
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+import org.springframework.data.annotation.Id;
+import org.springframework.data.mongodb.core.aggregation.ArrayOperators;
+import org.springframework.data.mongodb.core.mapping.Document;
+
+@Document
+@Setter
+@Getter
+@NoArgsConstructor
+@AllArgsConstructor
+public class Address {
+
+    @Id
+    private Integer id;
+    private String address;
+    private String city;
+    private String pincode;
+    private String addressType;
+
+}

src/main/java/com/example/demo/model/Department.java

+package com.example.demo.model;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+import org.springframework.data.annotation.Id;
+import org.springframework.data.mongodb.core.mapping.Document;
+
+@Document
+@Setter
+@Getter
+@NoArgsConstructor
+@AllArgsConstructor
+public class Department {
+
+    @Id
+    private Integer id;
+    private String depName;
+
+}

src/main/java/com/example/demo/model/Employee.java

+package com.example.demo.model;
+
+import lombok.*;
+import org.springframework.context.annotation.Scope;
+import org.springframework.context.annotation.ScopedProxyMode;
+import org.springframework.data.annotation.Id;
+import org.springframework.data.mongodb.core.mapping.Document;
+
+import java.util.Collections;
+
+@Document
+@Setter
+@Getter
+@NoArgsConstructor
+@AllArgsConstructor
+@Builder
+@Scope(scopeName = "request",proxyMode = ScopedProxyMode.TARGET_CLASS)
+public class Employee {
+    @Id
+    private Integer id;
+    private String name;
+    private String role;
+    private Integer sal;
+
+}

src/main/java/com/example/demo/repository/EmployeeRepository.java

+package com.example.demo.repository;
+
+import com.example.demo.model.Employee;
+import org.springframework.data.mongodb.repository.Query;
+import org.springframework.data.mongodb.repository.ReactiveMongoRepository;
+import org.springframework.stereotype.Repository;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.util.UUID;
+
+@Repository
+public interface EmployeeRepository extends ReactiveMongoRepository<Employee, Integer> {
+
+    Flux<Employee> findAll();
+    @Query(value = "{'sal' : ?0}")
+    Flux<Employee> findAllBySal(Integer sal);
+    Mono<Employee> findById();
+}

src/main/java/com/example/demo/service/EmployeeServiceImpl.java

+package com.example.demo.service;
+
+import com.example.demo.exceptions.EmployeeNotFoundException;
+import com.example.demo.model.Employee;
+import com.example.demo.repository.EmployeeRepository;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.logging.LogFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.data.domain.Sort;
+import org.springframework.data.mongodb.core.ReactiveMongoTemplate;
+import org.springframework.data.mongodb.core.aggregation.*;
+import org.springframework.data.mongodb.core.query.Criteria;
+import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.data.mongodb.core.query.Update;
+import org.springframework.stereotype.Service;
+import org.springframework.util.StringUtils;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.logging.Logger;
+import java.util.stream.Stream;
+
+@Service
+
+public class EmployeeServiceImpl implements IEmployeeService  {
+
+    private static final Logger logger = Logger.getLogger(EmployeeServiceImpl.class.getName());
+    @Autowired
+    private  EmployeeRepository employeeRepository;
+
+    @Autowired
+    private ReactiveMongoTemplate reactiveMongoTemplate;
+
+
+    @Override
+    public Flux<Employee> findAll() {
+        return employeeRepository.findAll();
+    }
+    public Flux<Employee> findAllEmpBySal() {
+
+        AggregationOperation match =Aggregation.match(Criteria.where("role").in("President", "CEO"));
+       // AggregationOperation group = Aggregation.group("$_id").first("$name").as("role");
+        AggregationOperation sort = Aggregation.sort(Sort.by(Collections.singletonList(Sort.Order.desc("role"))));
+        List<AggregationOperation> operationList = new ArrayList<>();
+        operationList.add(match);
+       // operationList.add(group);
+        operationList.add(sort);
+        Aggregation typedAggregation = Aggregation.newAggregation(operationList);
+        Flux<Employee> employeeFlux = reactiveMongoTemplate.aggregate(typedAggregation, Employee.class, Employee.class);
+        return employeeFlux;
+    }
+
+    @Override
+    public Mono<Employee> findEmployeeById(Integer id) {
+            return employeeRepository.findById(id);
+    }
+    public Mono<Employee> updateEmployee(Employee employee){
+        return employeeRepository.findById(employee.getId())
+                .map(a ->employee)
+                .flatMap(this.employeeRepository::save);
+
+}
+    public Mono<Employee> updateEmployeeById(Integer id,  String name){
+
+                return employeeRepository.findById(id).flatMap(employee -> {
+                    Employee employee1 =employee;
+                    employee1.setName(name);
+                    return employeeRepository.save(employee1).map(employee2 -> employee2);
+                });
+
+      /*return   employeeRepository.findById(id).flatMap(employee -> {
+            Employee e = employee;
+            e.setName(name);
+          return employeeRepository.save(e);
+        });*/
+    }
+    public Flux<Employee> updateEmployeeBySal(Integer sal,String role){
+        Criteria criteria = new Criteria();
+        criteria.andOperator(Criteria.where("sal").gte(sal),Criteria.where("sal").lte(200000));
+        Query query = new Query(criteria);
+        return reactiveMongoTemplate.find(query,Employee.class).flatMap(employee -> {
+            Employee e = employee;
+            e.setRole(role);
+            return employeeRepository.save(e);
+        });
+      /*return   employeeRepository.findAll().
+              filter(a -> a.getSal()>sal).flatMap(employee -> {
+         // log.info("in service method of update employee ");
+            Employee emp = employee;
+            emp.setRole(role);
+            return employeeRepository.save(emp);
+        });*/
+
+    }
+    @Override
+    public void createEmp(Employee employee) {
+    logger.info("in Create Employee Method");
+      employeeRepository.save(employee).
+              log("employee name: "+employee.getName());
+    }
+}

src/main/java/com/example/demo/service/IEmployeeService.java

+package com.example.demo.service;
+
+import com.example.demo.model.Employee;
+import org.springframework.stereotype.Service;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+public interface IEmployeeService {
+
+    Flux<Employee> findAll();
+    Mono<Employee> findEmployeeById( Integer id);
+    void createEmp(Employee employee);
+}

src/main/resources/application.properties

+spring.data.mongodb.url=mongodb://localhost:27017/Employee
+
+server.port=8080
+## MongoDB default port
+dbport=27017
+
+##MongoDB database name
+dbname=TechGeekNextDB11
+
+
+
+
+

src/test/java/com/example/demo/DemoApplicationTests.java

+package com.example.demo;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+class DemoApplicationTests {
+
+	@Test
+	void contextLoads() {
+	}
+
+}