Draft memberwise init issues

[tchardin]

Does anyone else find the Draft memberwise init not working? Not sure if I have some macro issues but I can't seem to make it compile properly. Given a table like:

@Table
nonisolated struct Experiment: Identifiable {
    let id: UUID
    var interventionID: Intervention.ID
    var startDate: Date = Date()
    var endDate: Date?
}

I assume I should be able to do Experiment.Draft(interventionID: intervention.id) no? The compiler says Draft expects a whole Experiment struct in the initializer. To compile, I have to do this:

#Preview {
    let intervention = try! prepareDependencies {
           $0.defaultDatabase = try appDatabase()
           return try $0.defaultDatabase.write { db in
               return try Intervention.fetchOne(db)!
           }
       }
    NavigationStack {
        ExperimentEditor(experiment: Experiment.Draft(
            Experiment(id: UUID(), interventionID: intervention.id)
        ))
    }
}

Which defies the purpose of the Draft struct. Tried cleaning, reindexing etc a few times without success

[mbrandonw]

Hi @tchardin, this is mentioned in the docs but macros can't see other macro generated code, and so #Preview can't see Draft. You can either use the non-macro PreviewProvider or you can define a little define helpers outside of the macro that are called from the macro.

FWIW it seems almost certainly like a bug that #Preview has this limitation, but not sure if it will ever be fixed.

[tchardin]

Amazing thanks! I thought I was going crazy.