“SwiftData inheritance relationship”

What is the correct way to track the number of items in a relationship using SwiftData and SwiftUI? Imagine a macOS application with a sidebar that lists Folders and Tags. An Item can belong to a Folder and have many Tags. In the sidebar, I want to show the name of the Folder or Tag along with the number of Items in it. I feel like I'm missing something obvious within SwiftData to wire this up such that my SwiftUI views correctly updated whenever the underlying modelContext is updated. // The basic schema @Model final class Item { var name = Untitled Item var folder: Folder? = nil var tags: [Tag] = [] } @Model final class Folder { var name = Untitled Folder var items: [Item] = [] } @Model final class Tag { var name = Untitled Tag var items: [Item] = [] } // A SwiftUI view to show a Folder. struct FolderRowView: View { let folder: Folder // Should I use an @Query here?? // @Query var items: [Item] var body: some View { HStack { Text(folder.name) Spacer() Text(folder.items.count.forma

This simple test fails in my project. Similar code in my application also crashes. How do I debug the problem? What project settings are required. I have added SwiftData as a framework to test (and application) targets? Thanks, The problem is with: modelContext.insert(item) Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0) import XCTest import SwiftData @Model class FakeModel { var name: String init(name: String) { self.name = name } } @MainActor final class FakeModelTests: XCTestCase { var modelContext: ModelContext! override func setUp() { super.setUp() do { let container = try ModelContainer(for: FakeModel.self, configurations: ModelConfiguration(isStoredInMemoryOnly: true)) modelContext = container.mainContext } catch { XCTFail(Failed to create ModelContainer: (error)) modelContext = nil } } func testSaveFetchDeleteFakeItem() { guard let modelContext = modelContext else { XCTFail(ModelContext must be initialized) return } let item = FakeModel(name: Test) modelContext.inser

Environment visionOS 26 Xcode 26 Issue I am experiencing crash when trying to access a [String] from a @Model data, after dismissing an immersiveSpace and opening a WindowGroup. This crash only occurs when trying to access the [String] property of my Model. It works fine with other properties. Thread 1: Fatal error: This backing data was detached from a context without resolving attribute faults: PersistentIdentifier(...) Steps to Reproduce Open WindowGroup Dismiss window, open ImmersiveSpace Dismiss ImmersiveSpace, reopen WindowGroup Any guidance would be appreciated! @main struct MyApp: App { var body: some Scene { WindowGroup(id: main) { ContentView() } .modelContainer(for: [Item.self]) ImmersiveSpace(id: immersive) { ImmersiveView() } } } // In SwiftData model @Model class Item { var title: String = // Accessing this property works fine var tags: [String] = [] @storageRestrictions(accesses: _$backingData, initializes: _tags) init(initialValue) { _$backingData.setValue(forKey: . tags, to: initial

I'm working with SwiftData and SwiftUI and it's not clear to me if it is good practice to have a @ModelActor directly populate a SwiftUI view. For example when having to combine manual lab results and clinial results from HealthKit. The Clinical lab results are an async operation: @ModelActor actor LabResultsManager { func fetchLabResultsWithHealthKit() async throws -> [LabResultDto] { let manualEntries = try modelContext.fetch(FetchDescriptor()) let clinicalLabs = (try? await HealthKitService.getLabResults()) ?? [] return (manualEntries + clinicalLabs).sorted { $0.date > $1.date }.map { return LabResultDto(from: $0) } } } struct ContentView: View { @State private var labResults: [LabResultDto] = [] var body: some View { List(labResults, id: .id) { result in VStack(alignment: .leading) { Text(result.testName) Text(result.date, style: .date) } } .task { do { let labManager = LabResultsManager() labResults = try await labManager.fetchLabResultsWithHealthKit() } catch { // Handle error } } } } EDI

I've been seeing something that I find odd when using two SwiftData models where if I have one model (book, in this case) that has an optional array of another model (page, in this case), the optional array starts out as set to nil, but after about 20 seconds it updates to being an empty array. I see it in Previews and after building. Is this expected behavior? Should I just assume that if there is an optional array in my model it will eventually be initialized to an empty array? Code is below. import SwiftUI import SwiftData @Model final class Book { var title: String = New Book @Relationship var pages: [Page]? = nil init(title: String) { self.title = title } } @Model final class Page { var content: String = Page Content var book: Book? = nil init() { } } struct ContentView: View { @Environment(.modelContext) private var modelContext @Query private var books: [Book] var body: some View { NavigationSplitView { List { ForEach(books) { book in NavigationLink { Text((book.title)) Text(