核心数据，嵌套列表

问题描述

我尝试使用从嵌套列表中的 Core Data 获取的数据，但是当我添加“children: .listofTasksArray”时，会显示以下错误： “关键路径值类型'[listofTasks]？'无法转换为上下文类型“FetchedResults？” 这是核心数据文件

extension listofTasks {

    @nonobjc public class func fetchRequest() -> NSFetchRequest<listofTasks> {
        return NSFetchRequest<listofTasks>(entityName: "listofTasks")
    }

    @NSManaged public var addedDate: Date?
    @NSManaged public var color: String?
    @NSManaged public var favoriteIndex: Int16
    @NSManaged public var icon: String?
    @NSManaged public var id: UUID?
    @NSManaged public var index: Int16
    @NSManaged public var isArchived: Bool
    @NSManaged public var isFavorite: Bool
    @NSManaged public var isLocked: Bool
    @NSManaged public var title: String?
    @NSManaged public var isList: Bool
    @NSManaged public var origin: listofTasks?
    @NSManaged public var subLists: NSSet?
    
    // The wrapped items
    public var wrappedAddedDate: Date {
        return addedDate ?? Date()
    }

    // To convert the color from "String" to "Color" type
    public var wrappedColor: Color {
        return Color(colorName: color ?? "blue")
    }
    
    public var wrappedIcon: String {
        return icon ?? "ellipsis.circle.fill"
    }
    
    public var wrappedId: UUID {
        return id ?? UUID()
    }
    
    public var wrappedTitle: String {
        return title ?? "UnkNown Title"
    }
    
    public var listofTasksArray: [listofTasks]? {
        let set = subLists as? Set<listofTasks> ?? nil
        
        return set?.sorted { // sort by index
            $0.index > $1.index
        }
    }
}

这是我用来获取数据并在列表中使用它的列表代码，尝试使用 listofTasks 属性“listofTasksArray”作为列表的子项来制作嵌套列表。

struct ListsView: View {

    @FetchRequest(entity: listofTasks.entity(),sortDescriptors: [NSSortDescriptor(keyPath: \listofTasks.index,ascending: true)],animation: .default) private var lists: FetchedResults<listofTasks>

var body: some View {

    List(lists,children: \.listofTasksArray,rowContent: { Text($0.wrappedTitle) })

}
}

解决方法

数据容器的类型应该是相同的，所以尝试将 FetchedResults 包装到一个数组中，比如（可能需要对选项做一些调整）

var body: some View {
    List(Array(lists),children: \.listofTasksArray) { 
       Text($0.wrappedTitle
    }
}