I'm writing some tests to confirm the behavior of my app. White creating a model actor to delete objects I realized that ModelContext.model(for:) does return objects that are deleted. I was able to reproduces this with this minimal test case:
@Model class Activity {
init() {}
}
struct MyLibraryTests {
let modelContainer = try! ModelContainer(
for: Activity.self,
configurations: ModelConfiguration(
isStoredInMemoryOnly: true
)
)
init() throws {
let context = ModelContext(modelContainer)
context.insert(Activity())
try context.save()
}
@Test func modelForIdAfterDelete() async throws {
let context = ModelContext(modelContainer)
let id = try context.fetch(FetchDescriptor<Activity>()).first!.id
context.delete(context.model(for: id) as! Activity)
try context.save()
let result = context.model(for: id) as? Activity
#expect(result == nil) // Expectation failed: (result → MyLibrary.Activity) == nil
}
@Test func fetchDescriptorAfterDelete() async throws {
let context = ModelContext(modelContainer)
let id = try context.fetch(FetchDescriptor<Activity>()).first!.id
context.delete(context.model(for: id) as! Activity)
try context.save()
let result = try context.fetch(
FetchDescriptor<Activity>(predicate: #Predicate { $0.id == id })
).first
#expect(result == nil)
}
}
Here I create a new context, insert an model and save it.
The test modelForIdAfterDelete does fail, as result still contains the deleted object.
I also tried to check #expect(result!.isDeleted), but it is also false.
With the second test I use a FetchDescriptor to retrieve the object by ID and it correctly returns nil.
Shouldn't both methods use a consistent behavior?
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I have a simple SwiftUI application with CoreData and two views. One view displays all "Place" objects. You can create new places and you can show the details for the place.
Inside the second view you can add "PlaceItem"s to a place.
The problem is that, once a new "PlaceItem" is added to the viewContext, the @NSFetchRequest seems to forget about its additional predicates, which I set in onAppear. Then every place item is shown inside the details view. Once I update the predicate manually (the refresh button), only the items from the selected place are visible again.
Any idea how this can be fixed? Here's the code for my two views:
struct PlaceView: View {
@FetchRequest(sortDescriptors: []) private var places: FetchedResults<Place>
@Environment(\.managedObjectContext) private var viewContext
var body: some View {
NavigationView {
List(places) { place in
NavigationLink {
PlaceItemsView(place: place)
} label: {
Text(place.name ?? "")
}
}
}
.toolbar {
ToolbarItem(placement: .primaryAction) {
Button {
let place = Place(context: viewContext)
place.name = NSUUID().uuidString
try! viewContext.save()
} label: {
Label("Add", systemImage: "plus")
}
}
}
.navigationTitle("Places")
}
}
struct PlaceItemsView: View {
@ObservedObject var place: Place
@FetchRequest(sortDescriptors: []) private var items: FetchedResults<PlaceItem>
@Environment(\.managedObjectContext) private var viewContext
func updatePredicate() {
items.nsPredicate = NSPredicate(format: "place == %@", place)
}
var body: some View {
NavigationView {
List(items) { item in
Text(item.name ?? "");
}
}
.onAppear(perform: updatePredicate)
.toolbar {
ToolbarItem(placement: .primaryAction) {
Button {
let item = PlaceItem(context: viewContext)
item.place = place
item.name = NSUUID().uuidString
try! viewContext.save()
} label: {
Label("Add", systemImage: "plus")
}
}
ToolbarItem(placement: .navigationBarLeading) {
Button(action: updatePredicate) {
Label("Refresh", systemImage: "arrow.clockwise")
}
}
}
.navigationTitle(place.name ?? "")
}
}
struct ContentView: View {
@Environment(\.managedObjectContext) private var viewContext
var body: some View {
NavigationView {
PlaceView()
}
}
}
Thanks!