hello everyone. we are developing a kotlin multipl...

# multiplatform

[erfan]

hello everyone. we are developing a kotlin multiplatform app using the template in here . We are targeting windows, ios & android, and we are using sqldelight for database and koin for DI. In sqldelight, as stated in it's documentation , we need a "DriverFactory" class that is responsible for creating the sql driver for each platform. to achieve this, in commonMain we have:

import com.example.Database

expect class DriverFactory {
  fun createDriver(): SqlDriver
}

fun createDatabase(driverFactory: DriverFactory): Database {
  val driver = driverFactory.createDriver()
  val database = Database(driver)

  // Do more work with the database (see below).
}

in androidMain:

actual class DriverFactory(private val context: Context) {
  actual fun createDriver(): SqlDriver {
    return AndroidSqliteDriver(Database.Schema, context, "test.db") 
  }
}

in jvmMain:

actual class DriverFactory {
  actual fun createDriver(): SqlDriver {
    val driver: SqlDriver = JdbcSqliteDriver(JdbcSqliteDriver.IN_MEMORY)
    Database.Schema.create(driver)
    return driver
  }
}

as you can see, the constructor for these classes are different. when I implement the exact same thing stated in sqldelight documentation, I get this compile error :

Actual class 'DriverFactory' has no corresponding members for expected class members:
public constructor DriverFactory() defined in nikted.fitting.compose.kmp.platform.DriverFactory The following declaration is incompatible because number of value parameters is different:
public constructor DriverFactory(context: Context) defined in nikted.fitting.compose.kmp.platform.DriverFactory

I have tried putting aside koin ( only for this class ) and using the direct singleton instance of Android like this:

actual class DriverFactory {
    val context = AndroidApp.INSTANCE.applicationContext
    actual fun createDriver(): SqlDriver {
        return AndroidSqliteDriver(FittingDb.Schema, context, "FittingDb.db")
    }
}

but it will lead to other problems like when testing the application on android. I would really appreciate it if someone could show me a way that I can resolve this dependency from koin instead of creating a direct instance. thanks

[Michael Paus]

This may not be the best was to do it but it has worked for me. This is my Android implementation of the factory.

actual class DatabaseDriverFactoryImpl actual constructor() : DatabaseDriverFactory {

    private lateinit var activity: ComponentActivity

    fun init(activity: ComponentActivity) {
        this.activity = activity
    }

    override fun createDatabaseDriver(dbFilePath: String): SqlDriver {
        return AndroidSqliteDriver(AIPDatabase.Schema, activity.applicationContext, dbFilePath)
    }

}

As you can see I have added an init method to it. I call this when the model is initialized from the Activity like this:

val databaseDriverFactory: DatabaseDriverFactory by inject()
(databaseDriverFactory as DatabaseDriverFactoryImpl).init(activity)

[Darron Schall]

Create the DriverFactory as part of a platformModule that each platform defines. You can see a concrete example of this kind of approach in https://github.com/touchlab/KaMPKit.

• Have the common Koin module leverage the platform module: https://github.com/touchlab/KaMPKit/blob/main/shared/src/commonMain/kotlin/co/touchlab/kampkit/Koin.kt#L24 - Note that the expect is here at the end of that file: https://github.com/touchlab/KaMPKit/blob/main/shared/src/commonMain/kotlin/co/touchlab/kampkit/Koin.kt#L87
• Create the Android platformModule in androidMain: https://github.com/touchlab/KaMPKit/blob/main/shared/src/androidMain/kotlin/co/touchlab/kampkit/KoinAndroid.kt#L12
• Create the iOS platformModule in iOSMain: https://github.com/touchlab/KaMPKit/blob/main/shared/src/iosMain/kotlin/co/touchlab/kampkit/KoinIOS.kt#L30