AlbGarciam/KC-Android-II

(Educative Purposes) Sample app for Android implemented with Kotlin. It uses Koin as dependency injector and Room for local database

Create a custom application

1. Create a subclass of application (TaskApp in our case)
2. Go to manifest
3. An application add modifier name to application object

Add Room

In order to add Room:

1. Prepare project

// Add plugin
apply plugin: 'kotlin-kapt'

// Add dependencies
implementation "androidx.room:room-runtime:2.1.0-rc01"
kapt "androidx.room:room-compiler:2.1.0-rc01"

2. Create entity

TableName is the name of the table which will be used on TaskEntityDao

@Entity(tableName = "tasks")
data class TaskEntity(
    @PrimaryKey(autoGenerate = true)
    val id: Long,
    val content: String,
    val createdAt: LocalDateTime,
    val isHighPriority: Boolean,
    val isFinished: Boolean
)

3. Add DAO

@Dao
interface TaskDao {

    @Query("SELECT * FROM tasks") // tasks is the name of the table
    suspend fun getAll(): List<TaskEntity>

    @Query("SELECT * FROM tasks WHERE id = :id")
    suspend fun getTaskById(id: Long): TaskEntity

    @Insert
    suspend fun insert(taskEntity: TaskEntity)

    @Update
    suspend fun update(taskEntity: TaskEntity)

    @Delete
    suspend fun delete(taskEntity: TaskEntity)

}

As we are going to store a non-primitive attribute, we have to convert date to a primitive data. To do that, we create a typeconverter

4. Add Database

// Each entity is a SQL table
@Database(entities = [TaskEntity::class], version = 1)
abstract class TaskDatabase {
    
    abstract fun getTaskDao(): TaskDao
    
}

Add Koin

1. Add gradle dependency

implementation 'org.koin:koin-android:2.0.1'
implementation 'org.koin:koin-android-viewmodel:2.0.1'

2. Add the module

val appModule = module{
    single {
        Room.databaseBuilder(
            androidContext(),
            TaskDatabase::class.java,
            "tasks.db"
        ).build()
    }

    factory { // We want that DAO is updated every time we access to it
        get<TaskDatabase>().getTaskDao()
    }


    single {
        TaskRepositoryImpl(get()) // this will call the factory
    }
}

3. Use Koin

// On task app
startKoin {
      androidLogger()
      androidContext(this@TaskApp)
      modules(appModule) // Here we instantiate our database
}

To customize the application you have to go to Android manifest and set android:name=".TaskApp" tag to customize the app. Where TaskApp is the class of your custom class