Swift Data Merge Contexts Publish

Using Swift
1

I need to edit a persisted SwiftData item in an isolated context, because if not is isolated with every change triggers expensive computations.

When the edit is done and I save the temporal context. I expect that the temporal context is merged with the main context and all the views that have a dependency with the edited Item.id be invalidated and updated. But not. When I dismiss the eItemEditView and temporalContext.save() is triggered the ItemNormalView that has a dependency with the Item.id remains not updated so I have to do a non elegant either reliable workaround.

What is the canonical way of do it?

The most relevant code:

struct ItemEditView: View {
    
    @Bindable var temporalItem: Item
    
    let temporalContext: ModelContext
    @Binding var updater: Bool
    
    init(itemID: PersistentIdentifier, 
         container: ModelContainer,
         updater: Binding<Bool>){
        temporalContext = ModelContext(container)
        temporalContext.autosaveEnabled = false
        self.temporalItem = temporalContext.model(for: itemID) as! Item
        self._updater = updater
    }
    
    var body: some View {
        TextField("", text: $temporalItem.name)
        .onDisappear{
            Task{
                try! temporalContext.save()
                
                //Workaround:
                try? await Task.sleep(nanoseconds:1_000_000_000)
                updater.toggle()
            }
        }
    }
}

struct ItemView: View {
    
    let item: Item
    
    @Environment(\.modelContext) private var modelContext
    @State private var itemEditorViewModalViewIsPresented = false
    @State private var updater = false
    
    var body: some View {
        VStack{
            ItemNornalView(item: item, updater: $updater)
            Button("Show Edit Modal View"){
                itemEditorViewModalViewIsPresented.toggle()
            }
        }
        .sheet(isPresented: $itemEditorViewModalViewIsPresented){
            ItemEditView(itemID: item.id, container: modelContext.container, updater: $updater)
        }
    }
}

struct ItemNornalView: View {
    
    let item: Item
    
    @Binding var updater: Bool
    
    var body: some View {
        
        let _ = Self._printChanges()
        
        Text("\(updater)").scaleEffect(0).hidden()
        Text("Item name: \(item.name)")
    }
}

The rest of the code:

struct ContentView: View {

    var body: some View {
        TabView{
            MetricsView().tabItem { Text("Metrics") }
            ItemsList().tabItem { Text("List") }
        }
    }
}

struct MetricsView: View {
    
    @Query private var items: [Item]
    
    var body: some View {
        Chart{
            BarMark(x: .value("x", "Average"), y: .value("y", expensiveComputation(items: items)))
        }
    }
    
    private func expensiveComputation(items: [Item])->Double{
        //...
        return 1.0
    }
}

struct ItemsList: View {
    
    @Query private var items: [Item]
    
    @Environment(\.modelContext) private var modelContext
    @State var path = NavigationPath()
    
    var body: some View {
        
        let _ = Self._printChanges()
        
        NavigationStack(path: $path) {
            List {
                ForEach(items) { item in
                    Button{
                        path.append(item)
                    }label:{
                        ItemRowView(item: item)
                    }
                }
                .onDelete(perform: deleteItems)
            }
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    EditButton()
                }
                ToolbarItem {
                    Button(action: addItem) {
                        Label("Add Item", systemImage: "plus")
                    }
                }
            }
            .navigationDestination(for: Item.self){ item in
                ItemView(item:item)
            }
        }
    }
    
    private func addItem() {
        withAnimation {
            let newItem = Item()
            modelContext.insert(newItem)
            try! modelContext.save()
        }
    }

    private func deleteItems(offsets: IndexSet) {
        withAnimation {
            for index in offsets {
                modelContext.delete(items[index])
            }
        }
    }
}