KTLN-450: Iterating All Fields of a Data Class without Reflection in Kotlin (#869)

* added unit tests

* fixed unit tests

* made some changes

* code refactor

Author: nappy29

core-kotlin-modules/core-kotlin-lang-oop-4/build.gradle.kts

@@ -0,0 +1,35 @@
+plugins {
+    kotlin("jvm") version "1.8.21"
+    kotlin("kapt") version "1.8.21"
+    id("java")
+}
+
+group = "org.example"
+version = "1.0-SNAPSHOT"
+
+repositories {
+    mavenCentral()
+    maven { url = uri("https://jitpack.io") }
+}
+
+buildscript {
+    dependencies {
+        classpath("org.jlleitschuh.gradle:ktlint-gradle:7.1.0")
+    }
+}
+
+dependencies {
+//    testImplementation("org.junit.jupiter:junit-jupiter-api:5.8.1")
+//    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:5.8.1")
+    compileOnly("com.github.LunarWatcher:KClassUnpacker:v1.0.1")
+    testImplementation(kotlin("test"))
+}
+
+kapt {
+    dependencies {
+        kapt("com.github.LunarWatcher:KClassUnpacker:v1.0.1")
+    }
+}
+tasks.getByName<Test>("test") {
+    useJUnitPlatform()
+}

core-kotlin-modules/core-kotlin-lang-oop-4/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.0-bin.zip
+networkTimeout=10000
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

core-kotlin-modules/core-kotlin-lang-oop-4/settings.gradle.kts

@@ -0,0 +1,2 @@
+rootProject.name = "core-kotlin-lang-oop-4"
+

core-kotlin-modules/core-kotlin-lang-oop-4/src/main/kotlin/com/baeldung/iteratePropertiesOfDataClass/IteratePropertiesOfDataClass.kt

@@ -0,0 +1,11 @@
+package com.baeldung.iteratePropertiesOfDataClass
+
+fun getFields(person: Person): List<String> {
+    var list = mutableListOf<String>()
+    val cls = person
+    for(field in cls) {
+        list.add(field.toString())
+    }
+
+    return list
+}

core-kotlin-modules/core-kotlin-lang-oop-4/src/main/kotlin/com/baeldung/iteratePropertiesOfDataClass/Person.kt

@@ -0,0 +1,6 @@
+package com.baeldung.iteratePropertiesOfDataClass
+
+import oliviazoe0.processor.AutoUnpack
+
+@AutoUnpack
+data class Person(val name: String, val age: Int)

core-kotlin-modules/core-kotlin-lang-oop-4/src/test/kotlin/IteratePropertiesOfDataClassUnitTest.kt

@@ -0,0 +1,32 @@
+import com.baeldung.iteratePropertiesOfDataClass.Person
+import com.baeldung.iteratePropertiesOfDataClass.getFields
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class IteratePropertiesOfDataClassUnitTest {
+    @Test
+    fun `iterate fields using destructuring declaration`() {
+        val person = Person("Robert", 28)
+        val (name, age) = person
+        assertEquals("Robert", name)
+        assertEquals(28, age)
+    }
+
+    @Test
+    fun `iterate fields using componentN methods`() {
+        val person = Person("Robert", 28)
+        val fields = listOf(person.component1(), person.component2())
+
+        assertEquals("Robert", fields[0])
+        assertEquals(28, fields[1])
+    }
+
+    @Test
+    fun `iterate fields using KClassUnpacker plugin`() {
+        val person = Person("Robert", 28)
+        val list = getFields(person)
+
+        assertEquals("Robert", list[0])
+        assertEquals("28", list[1])
+    }
+}

kotlin-build-plugins/build.gradle.kts

@@ -1,14 +1,22 @@
 plugins {
     kotlin("jvm") version "1.8.21"
+    kotlin("kapt") version "1.8.21"
     id("io.gitlab.arturbosch.detekt") version "1.23.0"
-    id "org.jlleitschuh.gradle.ktlint" version "7.1.0"
+    id("org.jlleitschuh.gradle.ktlint") version "7.1.0"
 }
 
 repositories {
     mavenCentral()
 }
 
+buildscript {
+    dependencies {
+        classpath("org.jlleitschuh.gradle:ktlint-gradle:7.1.0")
+    }
+}
+
 dependencies {
     detektPlugins("io.gitlab.arturbosch.detekt:detekt-formatting:1.23.0")
-    classpath ("org.jlleitschuh.gradle:ktlint-gradle:7.1.0")
+    testImplementation(kotlin("test"))
 }
+