DataStore Serializer using kotlinx-serialization
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import androidx.datastore.core.DataStore | |
import androidx.datastore.core.Serializer | |
import kotlinx.coroutines.flow.first | |
import kotlinx.serialization.json.Json | |
import kotlinx.serialization.json.decodeFromStream | |
import kotlinx.serialization.json.encodeToStream | |
import java.io.InputStream | |
import java.io.OutputStream | |
/** | |
* DataStore Serializer using kotlinx-serialization. | |
* Default value is null. | |
*/ | |
fun <reified T : Any> DataStoreSerializer(): Serializer<T?> { | |
return object : Serializer<T?> { | |
override val defaultValue: T? = null | |
override suspend fun readFrom(input: InputStream): T? { | |
return if (input.isNotEmpty()) { | |
Json.decodeFromStream(input) | |
} else { | |
null | |
} | |
} | |
override suspend fun writeTo(t: T?, output: OutputStream) { | |
if (t != null) Json.encodeToStream(t, output) | |
} | |
private fun InputStream.isNotEmpty() = available() > 0 | |
} | |
} | |
suspend fun <T : Any> DataStore<T?>.clear(): T? = updateData { null } | |
suspend fun <T : Any> DataStore<T?>.requireValue(): T = checkNotNull(data.first()) |
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See also DataStoreNullableSerializer