Implement TodoItem Data Access Object (DAO) for Room Database

.gitignore

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+# Android Studio
+*.iml
+.gradle
+/local.properties
+/.idea/workspace.xml
+/.idea/libraries
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+
+# Gradle files
+gradle-app.setting
+!gradle-wrapper.jar
+.gradletasknamecache
+
+# Compiled class files
+*.class
+
+# Log files
+*.log
+
+# Package Files
+*.jar
+*.war
+*.nar
+*.ear
+*.zip
+*.tar.gz
+*.rar
+
+# Virtual machine crash logs
+hs_err_pid*
+
+# Android specific
+bin/
+gen/
+out/
+release/
+
+# Android Profiling
+*.hprof
+
+# Dependency directories
+/node_modules
+/jspm_packages
+
+# Editor directories and files
+.idea/
+.vscode/
+*.swp
+*.swo
+
+# Environment files
+.env
+
+# Secrets
+*.key
+secrets.json
+
+# Build output
+/build
+/dist
+/target

app/build.gradle.kts

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+plugins {
+    id("com.android.application")
+    id("kotlin-android")
+    id("kotlin-kapt")
+}
+
+android {
+    compileSdk = 33
+    defaultConfig {
+        applicationId = "com.example.todoapp"
+        minSdk = 24
+        targetSdk = 33
+        versionCode = 1
+        versionName = "1.0"
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+}
+
+dependencies {
+    // Room dependencies
+    val roomVersion = "2.5.1"
+    implementation("androidx.room:room-runtime:$roomVersion")
+    implementation("androidx.room:room-ktx:$roomVersion")
+    kapt("androidx.room:room-compiler:$roomVersion")
+
+    // Testing dependencies
+    testImplementation("androidx.room:room-testing:$roomVersion")
+    testImplementation("junit:junit:4.13.2")
+    androidTestImplementation("androidx.test.ext:junit:1.1.5")
+    androidTestImplementation("androidx.test.espresso:espresso-core:3.5.1")
+}

app/src/main/java/com/example/todoapp/data/dao/TodoItemDao.kt

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+package com.example.todoapp.data.dao
+
+import androidx.room.*
+import com.example.todoapp.data.model.TodoItem
+import kotlinx.coroutines.flow.Flow
+
+@Dao
+interface TodoItemDao {
+    /**
+     * Inserts a new todo item into the database.
+     * @param todoItem The todo item to insert
+     * @return The ID of the newly inserted item
+     */
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insert(todoItem: TodoItem): Long
+
+    /**
+     * Inserts multiple todo items into the database.
+     * @param todoItems The list of todo items to insert
+     * @return List of inserted item IDs
+     */
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insertAll(todoItems: List<TodoItem>): List<Long>
+
+    /**
+     * Updates an existing todo item.
+     * @param todoItem The todo item with updated information
+     */
+    @Update
+    suspend fun update(todoItem: TodoItem)
+
+    /**
+     * Deletes a specific todo item.
+     * @param todoItem The todo item to delete
+     */
+    @Delete
+    suspend fun delete(todoItem: TodoItem)
+
+    /**
+     * Retrieves a todo item by its ID.
+     * @param id The ID of the todo item
+     * @return The todo item or null if not found
+     */
+    @Query("SELECT * FROM todo_items WHERE id = :id")
+    suspend fun getById(id: Long): TodoItem?
+
+    /**
+     * Retrieves all todo items, sorted by creation date.
+     * @return A Flow of todo items
+     */
+    @Query("SELECT * FROM todo_items ORDER BY createdAt DESC")
+    fun getAllTodoItems(): Flow<List<TodoItem>>
+
+    /**
+     * Retrieves completed todo items.
+     * @return A Flow of completed todo items
+     */
+    @Query("SELECT * FROM todo_items WHERE isCompleted = 1 ORDER BY updatedAt DESC")
+    fun getCompletedTodoItems(): Flow<List<TodoItem>>
+
+    /**
+     * Retrieves active (not completed) todo items.
+     * @return A Flow of active todo items
+     */
+    @Query("SELECT * FROM todo_items WHERE isCompleted = 0 ORDER BY createdAt DESC")
+    fun getActiveTodoItems(): Flow<List<TodoItem>>
+
+    /**
+     * Deletes all todo items from the database.
+     */
+    @Query("DELETE FROM todo_items")
+    suspend fun deleteAll()
+
+    /**
+     * Counts the total number of todo items.
+     * @return The total number of todo items
+     */
+    @Query("SELECT COUNT(*) FROM todo_items")
+    suspend fun count(): Int
+}

app/src/main/java/com/example/todoapp/data/database/TodoDatabase.kt

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+package com.example.todoapp.data.database
+
+import android.content.Context
+import androidx.room.Database
+import androidx.room.Room
+import androidx.room.RoomDatabase
+import com.example.todoapp.data.dao.TodoItemDao
+import com.example.todoapp.data.model.TodoItem
+
+@Database(entities = [TodoItem::class], version = 1, exportSchema = false)
+abstract class TodoDatabase : RoomDatabase() {
+    abstract fun todoItemDao(): TodoItemDao
+
+    companion object {
+        @Volatile
+        private var INSTANCE: TodoDatabase? = null
+
+        fun getDatabase(context: Context): TodoDatabase {
+            return INSTANCE ?: synchronized(this) {
+                val instance = Room.databaseBuilder(
+                    context.applicationContext,
+                    TodoDatabase::class.java,
+                    "todo_database"
+                ).build()
+                INSTANCE = instance
+                instance
+            }
+        }
+    }
+}

app/src/main/java/com/example/todoapp/data/model/TodoItem.kt

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+package com.example.todoapp.data.model
+
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+
+@Entity(tableName = "todo_items")
+data class TodoItem(
+    @PrimaryKey(autoGenerate = true)
+    val id: Long = 0,
+    val title: String,
+    val description: String? = null,
+    val isCompleted: Boolean = false,
+    val createdAt: Long = System.currentTimeMillis(),
+    val updatedAt: Long = System.currentTimeMillis()
+)

app/src/test/java/com/example/todoapp/data/dao/TodoItemDaoTest.kt

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+package com.example.todoapp.data.dao
+
+import android.content.Context
+import androidx.room.Room
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.example.todoapp.data.model.TodoItem
+import com.example.todoapp.data.database.TodoDatabase
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.runBlocking
+import org.junit.After
+import org.junit.Assert.*
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.io.IOException
+
+@RunWith(AndroidJUnit4::class)
+class TodoItemDaoTest {
+    private lateinit var todoItemDao: TodoItemDao
+    private lateinit var database: TodoDatabase
+
+    @Before
+    fun createDatabase() {
+        val context = ApplicationProvider.getApplicationContext<Context>()
+        database = Room.inMemoryDatabaseBuilder(context, TodoDatabase::class.java)
+            .allowMainThreadQueries()
+            .build()
+        todoItemDao = database.todoItemDao()
+    }
+
+    @After
+    @Throws(IOException::class)
+    fun closeDatabase() {
+        database.close()
+    }
+
+    @Test
+    @Throws(Exception::class)
+    fun insertAndGetTodoItem() = runBlocking {
+        val todoItem = TodoItem(title = "Test Todo", description = "Test Description")
+        val id = todoItemDao.insert(todoItem)
+        val retrievedItem = todoItemDao.getById(id)
+
+        assertNotNull(retrievedItem)
+        assertEquals("Test Todo", retrievedItem?.title)
+        assertEquals("Test Description", retrievedItem?.description)
+    }
+
+    @Test
+    @Throws(Exception::class)
+    fun updateTodoItem() = runBlocking {
+        val todoItem = TodoItem(title = "Original Title")
+        val id = todoItemDao.insert(todoItem)
+
+        val updatedItem = todoItem.copy(id = id, title = "Updated Title")
+        todoItemDao.update(updatedItem)
+
+        val retrievedItem = todoItemDao.getById(id)
+        assertEquals("Updated Title", retrievedItem?.title)
+    }
+
+    @Test
+    @Throws(Exception::class)
+    fun deleteTodoItem() = runBlocking {
+        val todoItem = TodoItem(title = "Item to Delete")
+        val id = todoItemDao.insert(todoItem)
+
+        val retrievedItem = todoItemDao.getById(id)
+        assertNotNull(retrievedItem)
+
+        todoItemDao.delete(retrievedItem!!)
+        val deletedItem = todoItemDao.getById(id)
+        assertNull(deletedItem)
+    }
+
+    @Test
+    @Throws(Exception::class)
+    fun getAllTodoItems() = runBlocking {
+        val todoItems = listOf(
+            TodoItem(title = "Item 1"),
+            TodoItem(title = "Item 2"),
+            TodoItem(title = "Item 3")
+        )
+        todoItemDao.insertAll(todoItems)
+
+        val allItems = todoItemDao.getAllTodoItems().first()
+        assertEquals(3, allItems.size)
+    }
+
+    @Test
+    @Throws(Exception::class)
+    fun getCompletedTodoItems() = runBlocking {
+        val todoItems = listOf(
+            TodoItem(title = "Completed 1", isCompleted = true),
+            TodoItem(title = "Completed 2", isCompleted = true),
+            TodoItem(title = "Active", isCompleted = false)
+        )
+        todoItemDao.insertAll(todoItems)
+
+        val completedItems = todoItemDao.getCompletedTodoItems().first()
+        assertEquals(2, completedItems.size)
+    }
+}