I had to implement this migration for an object that was stored in DataStore using Protobuf and Kotlinx Serialisable on Android. The original object looked like this:

@Serializable
data class Assignment(val state: State)

@Serializable
sealed interface State {
  @Serializable
  data object Pending : State
   // More implementations
}

The new object was supposed to look like this:

@Serializable
sealed interface State {
  @Serializable
  data class Pending(val id: String) : State
   // More implementations
}

Continue reading “Fixing Android DataStore migration from a data object to a data class” →