NavigationSplitView with collapsable List and CoreData

Question

I am trying to set up a collapsible List in my Core Data backed macOS app to allow navigation in the side bar.

Project is the main entity and has a to-many relationship with File.

It should look something like this:

Project 1 >
    File1
    File2
    File3
    
Project 2 >
    File21
    File22
    File23

Where the > indicates it is collapsible.

The error I get is below the code:

public extension Project {
    var filesArray: [File]? {
        guard let set = files as? Set<File>, set.isEmpty == false else { return nil }
        return Array(set)
    }
}

struct SplitView: View {
    @Environment(\.managedObjectContext) private var viewContext

    @FetchRequest(
        entity: Project.entity(),
        sortDescriptors: [NSSortDescriptor(keyPath: \Project.name, ascending: true)]
    ) var projects: FetchedResults<Project>

    var body: some View {
        NavigationSplitView {
            List(projects, children: \.filesArray) { file in  // <<-- Error in this line
                Text(file.name ?? "no name")
            }
        } detail: {
            Text("Detail Area") // TO DO
        }
}

I get the following error for the children property:

Key path value type '[File]?' cannot be converted to contextual type 'FetchedResults?'

How can I fix this?

NavigationSplitView with collapsable List and CoreData

0 Answers0