usage.md

Usage

Overview

• Component package: app.common.data.source.database.room
• DI integration: app.di.platform.configureKoin

The integration includes the following components:

• AppDatabase: A pre-configured Room database designed to register all entities and DAO objects.
• AppRoomSource: Serves as a holder of the AppDatabase instance and acts as a service locator for all DAO objects.
• User and UserDao: An example entity and its associated DAO object. These classes serve as templates that can be used to create your own entities and DAOs.

Create new Entity and DAO

The official guide for defining entities can be found here: https://developer.android.com/training/data-storage/room/defining-data

Imagine you need to add a new entity called Address. Here are the steps to follow.

1. Create the Address entity class

You can use the User class in app.common.data.source.database.room.entity as a template.

@Entity(tableName = "address")
data class Address(
    @PrimaryKey(autoGenerate = true)
    var id: Int = 0,
    @ColumnInfo(name = "country")
    var country: String? = null,
    @ColumnInfo(name = "city")
    var city: String? = null,
    @ColumnInfo(name = "street")
    var street: String? = null,
)

2. Create the AddressDao interface

You can use the UserDao interface in app.common.data.source.database.room.dao as a template.

@Dao
interface AddressDao {
    @Insert
    fun create(vararg addresses: Address)
    @Update
    fun update(vararg addresses: Address)
    @Delete
    fun delete(vararg addresses: Address)
    @Query("SELECT * FROM address WHERE id = :id LIMIT 1")
    fun get(id: Long): Address?
    @Query("SELECT * FROM address")
    fun getAll(): List<Address>
    @Query("SELECT * FROM address")
    fun getAllAsFlow(): Flow<Address>
}

3. Register Address and AddressDao in AppDatabase

@Database(
    entities = [
        Address::class
    ],
    version = 1
)
abstract class AppDatabase : RoomDatabase() {

    abstract fun getAddressDao(): AddressDao

}

4. Register AddressDao in AppRoomSource

class AppRoomSource(
    private val databaseName: String = "db"
) {
    ...
    val addressDao by lazy { db.getAddressDao() }
    ...
}

Usage of DAO in your code

In this example, we will directly use AppRoomSource from the ViewModel to access AddressDao. However, it is recommended to create a separate Repository layer and call all data sources from there.

class AddressViewModel(
    private val roomSource: AppRoomSource
) : BaseViewModel() {

    val addresses = mutableStateOf(emptyList<Address>())

    override fun doBind() = async("Get all addresses") {
        val addressDao = roomSource.addressDao
        addressDao.getAllAsFlow().collectLatest(addresses::value::set)
    }

    fun onCreate(address: Address) = async("onCreate", appState) {
        val addressDao = roomSource.addressDao
        addressDao.create(address)
    }

    fun onDelete(address: Address) = async("onRemove", appState) {
        val addressDao = roomSource.addressDao
        addressDao.delete(address)
    }

}