【Kotlinプログラム入門】JetpackCompose＆RoomでSQLiteデータベースを操作する方法を勉強してみよう！

plugins {
    id 'com.android.application'
    id 'org.jetbrains.kotlin.android'
    //以下を追加
    id 'kotlin-kapt'
}

android {
    namespace 'com.example.roomtest'
    compileSdk 34

    defaultConfig {
        applicationId "com.example.roomtest"
        minSdk 30
        targetSdk 33
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
        vectorDrawables {
            useSupportLibrary true
        }
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_17
        targetCompatibility JavaVersion.VERSION_17
    }
    kotlinOptions {
        jvmTarget = '17'
    }
    buildFeatures {
        compose true
    }
    composeOptions {
        kotlinCompilerExtensionVersion '1.4.3'
    }
    packaging {
        resources {
            excludes += '/META-INF/{AL2.0,LGPL2.1}'
        }
    }
    kapt {
        useBuildCache = false
        correctErrorTypes = true
        mapDiagnosticLocations = true
        arguments {
            arg("room.schemaLocation", "$projectDir/schemas".toString())
        }
    }
}

dependencies {

    implementation 'androidx.core:core-ktx:1.9.0'
    implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.6.2'
    implementation 'androidx.activity:activity-compose:1.8.0'
    implementation platform('androidx.compose:compose-bom:2023.03.00')
    implementation 'androidx.compose.ui:ui'
    implementation 'androidx.compose.ui:ui-graphics'
    implementation 'androidx.compose.ui:ui-tooling-preview'
    implementation 'androidx.compose.material3:material3'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.5'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
    androidTestImplementation platform('androidx.compose:compose-bom:2023.03.00')
    androidTestImplementation 'androidx.compose.ui:ui-test-junit4'
    debugImplementation 'androidx.compose.ui:ui-tooling'
    debugImplementation 'androidx.compose.ui:ui-test-manifest'

    //公式ページを参考にRoomに必要な依存関係を追加 (以下を全部)
    implementation("androidx.room:room-runtime:2.5.0")
    annotationProcessor("androidx.room:room-compiler:2.5.0")

    // To use Kotlin annotation processing tool (kapt)
    kapt("androidx.room:room-compiler:2.5.0")

    // optional - Kotlin Extensions and Coroutines support for Room
    implementation("androidx.room:room-ktx:2.5.0")

    // optional - RxJava2 support for Room
    implementation("androidx.room:room-rxjava2:2.5.0")

    // optional - RxJava3 support for Room
    implementation("androidx.room:room-rxjava3:2.5.0")

    // optional - Guava support for Room, including Optional and ListenableFuture
    implementation("androidx.room:room-guava:2.5.0")

    // optional - Test helpers
    testImplementation("androidx.room:room-testing:2.5.0")

    // optional - Paging 3 Integration
    implementation("androidx.room:room-paging:2.5.0")
}

package com.example.roomtest

import androidx.room.ColumnInfo
import androidx.room.Entity
import androidx.room.PrimaryKey

@Entity(tableName = "users")
data class User(
    @PrimaryKey(autoGenerate = true) val id: Long = 0,
    @ColumnInfo(name = "name") val name: String,
    @ColumnInfo(name = "age") var age: Int
)

package com.example.roomtest

import androidx.room.Dao
import androidx.room.Delete
import androidx.room.Insert
import androidx.room.Query
import androidx.room.Update

@Dao
interface UserDao {
    @Query("SELECT * FROM users")
    fun getAllUsers(): List

    @Query("SELECT * FROM users WHERE id = :userId")
    fun getUserById(userId: Long): User?

    @Insert
    fun insertUser(user: User)

    @Update
    fun updateUser(user: User)

    @Delete
    fun deleteUser(user: User)

    @Query("DELETE FROM users WHERE id = :userId")
    fun deleteUserById(userId: Long)
}

package com.example.roomtest

import androidx.room.Database
import androidx.room.RoomDatabase

@Database(entities = [User::class], version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun userDao(): UserDao
}

package com.example.roomtest

import android.annotation.SuppressLint
import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.ui.tooling.preview.Preview
import androidx.room.Room
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.launch

class MainActivity : ComponentActivity() {
    @SuppressLint("CoroutineCreationDuringComposition")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            // データベースのインスタンスを取得
            val db = Room.databaseBuilder(
                applicationContext,
                AppDatabase::class.java, "user-database"
            ).build()

            // トランザクション内でデータベース操作を実行
            GlobalScope.launch(Dispatchers.IO) {
                db.runInTransaction {
                    try {
                        // UserDaoのインスタンスを取得
                        val userDao = db.userDao()

                        // 全ユーザーの取得と削除
                        var users = userDao.getAllUsers()
                        for (user in users) {
                            userDao.deleteUser(user)
                        }

                        // 登録前の件数表示
                        users = userDao.getAllUsers()
                        println("登録前 件数: ${users.size}")

                        // ユーザーの追加
                        val newUser = User(name = "チワワちゃん", age = 1)
                        userDao.insertUser(newUser)

                        // ユーザーの取得と表示
                        users = userDao.getAllUsers()
                        for (user in users) {
                            println("登録後 User: ${user.name}, Age: ${user.age}, ID: ${user.id}")
                        }

                        // ユーザーの更新
                        users[0].age = 2
                        userDao.updateUser(users[0])

                        val updatedUser = userDao.getUserById(users[0].id)
                        updatedUser?.let {
                            println("更新後 User: ${it.name}, Age: ${it.age}, ID: ${it.id}")
                        }

                        // ユーザーの削除
                        println("削除前 User: ${users[0].name}, Age: ${users[0].age}, ID: ${users[0].id}")
                        val userIdToDelete = updatedUser?.id ?: users[0].id
                        userDao.deleteUserById(userIdToDelete)

                        // 削除後の件数表示
                        users = userDao.getAllUsers()
                        println("削除後 件数: ${users.size}")

                        // エラーが発生しない場合は自動的にコミットされます

                    } catch (e: Exception) {
                        // 何らかのエラーが発生した場合はトランザクションが自動的にロールバックされます
                        throw e
                    }
                }
            }
        }
    }
}

@Composable
fun Greeting() {
    Text(
        text = "Roomに挑戦してみた件!"
    )
}

@Preview(showBackground = true)
@Composable
fun GreetingPreview() {
    Greeting()
}