created demo app by https://bit.ly/3fPxGgN

Author: nixos89

build.gradle.kts

@@ -1,35 +1,60 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
 plugins {
     java
     kotlin("jvm") version "1.5.10"
-    id("org.springframework.boot") version "2.4.4"
+    id("org.springframework.boot") version "2.5.0"
     id("io.spring.dependency-management") version "1.0.11.RELEASE"
     id("org.flywaydb.flyway") version "7.9.1"
+    kotlin("plugin.spring") version "1.5.10"
+    kotlin("plugin.jpa") version "1.5.10"
+    kotlin("plugin.allopen") version "1.5.10"
+    kotlin("kapt") version "1.5.10"
 }
 
+allOpen {
+    annotation("javax.persistence.Entity")
+    annotation("javax.persistence.Embeddable")
+    annotation("javax.persistence.MappedSuperclass")
+}
 
 group = "org.example"
 version = "1.0-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
 
-val javaVer = JavaVersion.VERSION_1_8
 
 repositories {
-    jcenter()
     mavenCentral()
 }
 
 dependencies {
     implementation("org.springframework.boot:spring-boot-starter-web")
-    testImplementation("org.springframework.boot:spring-boot-starter-test")
+    implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
+    implementation("org.jetbrains.kotlin:kotlin-reflect")
+    implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
+    developmentOnly("org.springframework.boot:spring-boot-devtools")
+    implementation("org.springframework.boot:spring-boot-starter-data-jpa")
+    testImplementation("org.springframework.boot:spring-boot-starter-test") {
+        exclude(module = "junit")
+        exclude(module = "mockito-core")
+    }
+    testImplementation("org.junit.jupiter:junit-jupiter-api")
+    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine")
+    testImplementation("com.ninja-squad:springmockk:3.0.1")
+    implementation("org.springframework.boot:spring-boot-starter-mustache")
     implementation("org.springframework.boot:spring-boot-starter-actuator")
-    implementation("org.springframework.data:spring-data-jpa:2.4.2")
-
+    runtimeOnly("com.h2database:h2")
+    kapt("org.springframework.boot:spring-boot-configuration-processor")
+//    runtimeOnly("org.postgresql:postgresql")
 }
 
-java {
-    sourceCompatibility = javaVer
-    targetCompatibility = javaVer
+tasks.withType<KotlinCompile> {
+    kotlinOptions {
+        freeCompilerArgs = listOf("-Xjsr305=strict")
+        jvmTarget = "1.8"
+    }
 }
 
-tasks.getByName<Test>("test") {
+tasks.withType<Test> {
     useJUnitPlatform()
 }

src/main/java/org/example/FirstJavaKotlinGradleApp.java renamed to src/main/java/org/example/java_kotlin/FirstJavaKotlinGradleApp.java

@@ -1,14 +1,17 @@
-package org.example;
+package org.example.java_kotlin;
 
+import org.example.java_kotlin.config.BlogProperties;
 import org.springframework.boot.CommandLineRunner;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 
 import java.util.Arrays;
 
 @SpringBootApplication
+@EnableConfigurationProperties(BlogProperties.class)
 public class FirstJavaKotlinGradleApp {
 
     public static void main(String[] args) {

src/main/java/org/example/HelloController.java renamed to src/main/java/org/example/java_kotlin/HelloController.java

@@ -1,15 +1,15 @@
-package org.example;
+package org.example.java_kotlin;
 
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.bind.annotation.RequestMapping;
 
 @RestController
 public class HelloController {
 
-    @RequestMapping("/")
-    public String index() {
-        return "Greetings from Spring Boot!";
-    }
+//    @RequestMapping("/")
+//    public String index() {
+//        return "Greetings from Spring Boot!";
+//    }
 
 
 

src/main/java/org/example/java_kotlin/config/BlogConfiguration.kt

@@ -0,0 +1,37 @@
+package org.example.java_kotlin.config
+
+import org.example.java_kotlin.model.Article
+import org.example.java_kotlin.model.User
+import org.example.java_kotlin.repositories.ArticleRepository
+import org.example.java_kotlin.repositories.UserRepository
+import org.springframework.boot.ApplicationRunner
+import org.springframework.context.annotation.Bean
+import org.springframework.context.annotation.Configuration
+
+@Configuration
+class BlogConfiguration {
+
+    @Bean
+    fun databaseInitializer(userRepository: UserRepository, articleRepository: ArticleRepository) = ApplicationRunner {
+        val smaldini = userRepository.save(
+            User("smaldini", "Stéphane", "Maldini")
+        )
+        articleRepository.save(
+            Article(
+                title = "Reactor Bismuth is out",
+                headline = "Lorem ipsum",
+                content = "dolor sit amet",
+                author = smaldini
+            )
+        )
+        articleRepository.save(
+            Article(
+                title = "Reactor Aluminium has landed",
+                headline = "Lorem ipsum",
+                content = "dolor sit amet",
+                author = smaldini
+            )
+        )
+
+    }
+}

src/main/java/org/example/java_kotlin/config/BlogProperties.kt

@@ -0,0 +1,11 @@
+package org.example.java_kotlin.config
+
+import org.springframework.boot.Banner
+import org.springframework.boot.context.properties.ConfigurationProperties
+import org.springframework.boot.context.properties.ConstructorBinding
+
+@ConstructorBinding
+@ConfigurationProperties("blog")
+data class BlogProperties(var title: String, val banner: Banner) {
+    data class Banner(val title: String? = null, val content: String)
+}

src/main/java/org/example/java_kotlin/controller/HtmlController.kt

@@ -0,0 +1,57 @@
+package org.example.java_kotlin.controller
+
+import org.example.java_kotlin.config.BlogProperties
+import org.example.java_kotlin.model.Article
+import org.example.java_kotlin.model.User
+import org.example.java_kotlin.repositories.ArticleRepository
+import org.example.java_kotlin.util.format
+import org.springframework.http.HttpStatus
+import org.springframework.stereotype.Controller
+import org.springframework.ui.Model
+import org.springframework.ui.set
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.PathVariable
+import org.springframework.web.server.ResponseStatusException
+
+@Controller
+class HtmlController(
+    private val articleRepository: ArticleRepository,
+    private val properties: BlogProperties
+) {
+
+    @GetMapping("/")
+    fun blog(model: Model): String {
+        model["title"] = properties.title
+        model["banner"] = properties.banner
+        model["articles"] = articleRepository.findAllByOrderByAddedAtDesc().map { it.render() }
+        return "blog"
+    }
+
+    @GetMapping("/article/{slug}")
+    fun article(@PathVariable slug: String, model: Model): String {
+        val article = articleRepository.findBySlug(slug)
+            ?.render()
+            ?: throw ResponseStatusException(HttpStatus.NOT_FOUND, "This article does not exist")
+        model["title"] = article.title
+        model["article"] = article
+        return "article"
+    }
+
+    fun Article.render() = RenderedArticle(
+        slug,
+        title,
+        headline,
+        content,
+        author,
+        addedAt.format()
+    )
+
+    data class RenderedArticle(
+        val slug: String,
+        val title: String,
+        val headline: String,
+        val content: String,
+        val author: User,
+        val addedAt: String
+    )
+}

src/main/java/org/example/java_kotlin/controller/HttpControllers.kt

@@ -0,0 +1,36 @@
+package org.example.java_kotlin.controller
+
+import org.example.java_kotlin.repositories.ArticleRepository
+import org.example.java_kotlin.repositories.UserRepository
+import org.springframework.http.HttpStatus
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.PathVariable
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+import org.springframework.web.server.ResponseStatusException
+
+@RestController
+@RequestMapping("/api/article")
+class ArticleController(private val articleRepository: ArticleRepository) {
+
+    @GetMapping("/")
+    fun findAll() = articleRepository.findAllByOrderByAddedAtDesc()
+
+    @GetMapping("/{slug}")
+    fun findOne(@PathVariable slug: String) = articleRepository
+        .findBySlug(slug) ?: throw ResponseStatusException(HttpStatus.NOT_FOUND, "This article does not exist!")
+
+}
+
+@RestController
+@RequestMapping("/api/user")
+class UserController(private val userRepository: UserRepository) {
+
+    @GetMapping("/")
+    fun findAll() = userRepository.findAll()
+
+    @GetMapping("/{login}")
+    fun findOne(@PathVariable login: String) = userRepository
+        .findByLogin(login) ?: throw ResponseStatusException(HttpStatus.NOT_FOUND, "This user does not exist!")
+
+}

src/main/java/org/example/controller/TodoController.kt renamed to src/main/java/org/example/java_kotlin/controller/TodoController.kt

@@ -1,13 +1,14 @@
-package org.example.controller
+package org.example.java_kotlin.controller
 
+import org.example.java_kotlin.model.Todo
 import org.springframework.web.bind.annotation.*
 
 @RestController
 @RequestMapping("/todos")
 class TodoController {
 
     @GetMapping("/{todoId}")
-    fun getTodo(@PathVariable("todoId") todoId: Long) {
+    fun getTodo(@PathVariable todoId: Long) {
         // TODO: implement `getTodo`
     }
 
@@ -16,10 +17,9 @@ class TodoController {
         // TODO: implement `getAllTodos`
     }
 
-    // TODO: Research how to implement Model class in Kotlin!
-//    @PostMapping
-//    fun saveTodo(TodoClass) {
-//
-//    }
+    @PostMapping
+    fun saveTodo(@RequestBody todo: Todo) {
+        // TODO: implement `saveTodo`
+    }
 
 }

src/main/java/org/example/java_kotlin/model/Entities.kt

@@ -0,0 +1,27 @@
+package org.example.java_kotlin.model
+
+import org.example.java_kotlin.util.toSlug
+import java.time.LocalDateTime
+import javax.persistence.Entity
+import javax.persistence.GeneratedValue
+import javax.persistence.Id
+import javax.persistence.ManyToOne
+
+@Entity
+class User(
+    var login: String,
+    var firstname: String,
+    var lastname: String,
+    var description: String? = null,
+    @Id @GeneratedValue var id: Long? = null)
+
+@Entity
+class Article(
+    var title: String,
+    var headline: String,
+    var content: String,
+    @ManyToOne var author: User,
+    var slug: String = title.toSlug(),
+    var addedAt: LocalDateTime = LocalDateTime.now(),
+    @Id @GeneratedValue var id: Long? = null)
+

src/main/java/org/example/java_kotlin/model/Todo.kt

@@ -0,0 +1,13 @@
+package org.example.java_kotlin.model
+
+import javax.persistence.Entity
+import javax.persistence.GeneratedValue
+import javax.persistence.Id
+
+/* TODO: Try LATER to place `data` modifier before `class`
+    keyword to check behaviour when using it with Hibernate */
+@Entity
+class Todo(
+    @Id @GeneratedValue var todoId: Long,
+    var title: String,
+    var description: String)