I have a simple Core Data macOS app, with its Data Model as follow:

Entity:
Data

Attributes:
text     String
starred  Boolean
date     Date 

I'm trying to access the data from a custom menu I created, iterate it and (in the future) save it to disk.

I've been trying to add code directly to the menu item created as:

@main
struct My_DataApp: App {
    let persistenceController = PersistenceController.shared
    
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environment(\.managedObjectContext, persistenceController.container.viewContext)
                .frame(minWidth: 560, maxWidth: .infinity,
                       minHeight: 300, maxHeight: .infinity)
                .onAppear {
                    NSWindow.allowsAutomaticWindowTabbing = false
                }
        }
        .windowToolbarStyle(UnifiedWindowToolbarStyle(showsTitle: false))
        .commands{
            CommandGroup(after: CommandGroupPlacement.newItem) {
                Button("Export Data") {
                    @FetchRequest(entity: Data.entity(), sortDescriptors: [NSSortDescriptor(keyPath: \Data.date, ascending: false)], animation: .default)
                    var DataItems: FetchedResults<Data>
                    for data in DataItems {
                        print("\(String(describing: data.text))")
                    }

                }                
            }
        }

    }
}

Of course Xcode is complaining:

I understand the error but I don't know how else to think about accessing the data from the menu.

I saw a few posts here in SO about the same error, and I tried to add code to the .onAppear section but same error happens there.

Thanks for any help.

CodePudding user response：

You can use NSFetchRequest directly and execute it by view context, like

Button("Export Data") {

  let fetchRequest = Data.fetchRequest()
  // .. set up parameters

  let context = self.persistenceController.container.viewContext
  if let result = try? context.fetch(fetchRequest) {
    for data in result {
        print("\(String(describing: data.text))")
    }
  }
}