[Bael 1687] - Code Peer Review (#4034)

* [BAEL-1641] Find all pairs of numbers in an array that add up to a given sum

* Commiting editor's suggested changes

* Commiting article Spring Data Reactive Mongo DB microservice in Kotlin

* Revert commit for BAEL 1687 - Moving those files to a new branch

* [BAEL-1687] - Real-time data streaming using Reactive MongoDB and Kotlin

* Reverting changes [BAEL-1641] - Not from this branch

* [BAEL-1687] - Code Peer Review - Added suggested changes

* [BAEL-1687] - Code Peer Review - Grzegorz's code refactor & delete unnecessary code

* [BAEL-1687] - Code Peer Review - Grzegorz's code refactor & delete unnecessary code

* [BAEL-1687] - Code Peer Review - Fixed emitter

algorithms/README.md

@@ -20,4 +20,4 @@
 - [A Maze Solver in Java](http://www.baeldung.com/java-solve-maze)
 - [Create a Sudoku Solver in Java](http://www.baeldung.com/java-sudoku)
 - [Displaying Money Amounts in Words](http://www.baeldung.com/java-money-into-words)
-- [A Collaborative Filtering Recommendation System in Java](http://www.baeldung.com/java-collaborative-filtering-recommendations)
+- [A Collaborative Filtering Recommendation System in Java](http://www.baeldung.com/java-collaborative-filtering-recommendations)

spring-data-5-reactive/pom.xml

@@ -8,7 +8,7 @@
     <packaging>jar</packaging>
     <name>Spring-5-data-reactive</name>
     <description>Spring-5-data-reactive with Springboot 2.0.1</description>
-
+  
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
@@ -16,6 +16,13 @@
         <relativePath/> <!-- lookup parent from repository -->
     </parent>
 
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+        <java.version>1.8</java.version>
+        <kotlin.version>1.2.40</kotlin.version>
+    </properties>
+
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
@@ -56,8 +63,24 @@
             <artifactId>kotlin-stdlib-jdk8</artifactId>
             <version>${kotlin.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib-jdk8</artifactId>
+            <version>${kotlin.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-test</artifactId>
+            <version>${kotlin.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib-jdk8</artifactId>
+            <version>${kotlin.version}</version>
+        </dependency>
     </dependencies>
-
+    
     <repositories>
         <repository>
             <id>spring-libs-snapshot</id>
@@ -65,7 +88,7 @@
             <url>http://repo.spring.io/libs-snapshot</url>
         </repository>
     </repositories>
-
+    
     <build>
         <sourceDirectory>src/main/kotlin</sourceDirectory>
         <plugins>
@@ -112,12 +135,4 @@
             </plugin>
         </plugins>
     </build>
-
-    <properties>
-        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-        <kotlin.version>1.2.20</kotlin.version>
-        <javax.ws.rs-api.version>2.1</javax.ws.rs-api.version>
-    </properties>
-
 </project>

spring-data-5-reactive/src/main/kotlin/com/baeldung/Application.kt

@@ -1,4 +1,4 @@
-package org.jetbrains.kotlin.demo
+package com.baeldung
 
 import org.springframework.boot.SpringApplication
 import org.springframework.boot.autoconfigure.SpringBootApplication
@@ -9,4 +9,3 @@ class Application
 fun main(args: Array<String>) {
     SpringApplication.run(Application::class.java, *args)
 }
-

spring-data-5-reactive/src/main/kotlin/com/baeldung/EventRepository.kt

@@ -1,5 +1,9 @@
 package com.baeldung
 
+import org.springframework.data.mongodb.core.mapping.Document
 import org.springframework.data.mongodb.repository.ReactiveMongoRepository
 
 interface EventRepository : ReactiveMongoRepository<Event, String>
+
+@Document
+data class Event(val id: String, val name: String)

spring-data-5-reactive/src/main/kotlin/com/baeldung/MongoConfig.kt

@@ -13,21 +13,13 @@ import org.springframework.data.mongodb.repository.config.EnableReactiveMongoRep
 @EnableReactiveMongoRepositories(basePackageClasses = arrayOf(EventRepository::class))
 class MongoConfig : AbstractReactiveMongoConfiguration() {
 
-    override fun reactiveMongoClient(): com.mongodb.reactivestreams.client.MongoClient {
-        return mongoClient()
-    }
+    override fun reactiveMongoClient(): MongoClient = mongoClient()
 
     @Bean
-    fun mongoClient(): MongoClient {
-        return MongoClients.create()
-    }
+    fun mongoClient(): MongoClient = MongoClients.create()
 
-    override fun getDatabaseName(): String {
-        return "mongoDatabase"
-    }
+    override fun getDatabaseName(): String = "mongoDatabase"
 
     @Bean
-    override fun reactiveMongoTemplate(): ReactiveMongoTemplate {
-        return ReactiveMongoTemplate(mongoClient(), databaseName)
-    }
+    override fun reactiveMongoTemplate(): ReactiveMongoTemplate = ReactiveMongoTemplate(mongoClient(), databaseName)
 }

spring-data-5-reactive/src/main/kotlin/com/baeldung/SendEmitter.kt

@@ -1,43 +1,16 @@
 package com.baeldung
 
+import org.springframework.http.MediaType
 import org.springframework.web.bind.annotation.GetMapping
 import org.springframework.web.bind.annotation.RequestParam
 import org.springframework.web.bind.annotation.RestController
-import org.springframework.web.servlet.mvc.method.annotation.SseEmitter
-import reactor.core.publisher.Flux
-import reactor.core.publisher.Mono
 import java.util.*
-import javax.ws.rs.core.MediaType
 
 
 @RestController
 class SendEmitter(val eventRepository: EventRepository) {
 
-    private var emitter = SseEmitter()
-
-    /**
-     * Save and send an SSE to all subscribed clients
-     */
-    @GetMapping("/saveEvent")
-    fun executeExample(@RequestParam("eventName") eventName: String): Flux<Event> {
-        // Create new event
-        var event = Event(UUID.randomUUID().toString(), eventName)
-        // Save event
-        var stream = eventRepository.saveAll(Mono.just(event))
-        // Send event
-        emitter.send(SseEmitter.event().data(event))
-        // Return SSE
-        return stream
-    }
-
-    /**
-     * Receive SSEs
-     */
-    @GetMapping(value = "/receiveChanges")
-    fun handle(): SseEmitter {
-        // Create new emitter
-        this.emitter = SseEmitter()
-        // Return SSE
-        return emitter
-    }
+    @GetMapping(value = "/save", produces = arrayOf(MediaType.TEXT_EVENT_STREAM_VALUE))
+    fun executeExample(@RequestParam("eventName") eventName: String) =
+            eventRepository.save(Event(UUID.randomUUID().toString(), eventName)).flux()
 }

spring-data-5-reactive/src/main/resources/static/index.html

@@ -1,33 +1,39 @@
 <html>
 <body>
 
-<form method="get" action="/saveEvent">
+<!-- Save new event -->
+<form method="get" action="/save">
     <input type="text" name="eventName">
     <button type="submit">Save new event</button>
 </form>
 
 
-<!-- Here will be painted each new received Server-Sent event's content-->
+<!-- Receive saved event -->
 <div id="content"></div>
 
 <script>
-    var source = new EventSource("receiveChanges");
+
+
+    let source = new EventSource("save");
 
     source.addEventListener('message', function (e) {
         console.log('New message is received');
         const index = JSON.parse(e.data);
-        const content = "New event added: " + index.name + "<br>";
+        const content = `New event added: ${index.name}<br>`;
         document.getElementById("content").innerHTML += content;
     }, false);
+
     source.addEventListener('open', function(e) {
         console.log('The connection has been opened');
     }, false);
+
     source.addEventListener('error', function(e) {
         if (e.readyState == EventSource.CLOSED){
             console.log('The connection has been closed');
         }
     }, false);
 
+
 </script>
 </body>
 <html>