Realm Swift 中的一对多关系如何？

Question

我是 Realm Swift 的新手。我想在 Swift3.0 中实现一对多的关系

我有文件夹列表，每个文件夹可能有子文件夹列表。所以我创建了两个 relam 文件，如下所示。

文件夹领域类

 class FolderRealm: Object {

    dynamic var folderName : String?
    dynamic var createdDate : Date?
    let subFolders = List<SubFolderRealm>()
 }

子文件夹领域类

 class SubFolderRealm: Object {

   dynamic var subFolderName : String?
   dynamic var createdDate : Date? 

 }

为了添加文件夹，我使用了以下代码行

let folder : FolderRealm  = FolderRealm()
folder.folderName = searchBarObj.text!
folder.createdDate = Date()
 try! realm.write {
   realm.add(folder)
 }

我有疑问，如何将子文件夹数据添加到文件夹和子文件夹领域？

Answer 1

首先，考虑只使用一个Folder 类型而不是两个，当所有数据都相同时，没有意义的子文件夹对象。

class Folder : Object {
    dynamic var folderName:String = ""
    dynamic var createdDate:Date = Date()
}

其次，对于您的情况，您可能希望使用LinkingObjects。

class Folder : Object {
    dynamic var folderName:String = ""
    dynamic var createdDate:Date = Date()
    dynamic var parentFolder:Folder? = nil

    let subfolders = LinkingObjects(fromType: Folder.self, property: "parentFolder")
}

你会创建这样的对象：

let parentFolder = Folder()
let subfolder1 = Folder()
let subfolder2 = Folder()

parentFolder.folderName = "whatever"

subfolder1.parentFolder = parentFolder
subfolder2.parentFolder = parentFolder

let realm = try! Realm()
try! realm.write { realm.add([parentFolder, subfolder1, subfolder2])}

Answer 2

在try! realm.write { realm.add(folder) } 行之前试试这个

let folder : FolderRealm  = FolderRealm()
folder.folderName = searchBarObj.text!
folder.createdDate = Date()

let subFolder1: SubFolderRealm = SubFolderRealm()
subFolder1.subFolderName = "any string"
subFolder1.createdDate = Date()

let subFolder2: SubFolderRealm = SubFolderRealm()
subFolder2.subFolderName = "any string"
subFolder2.createdDate = Date()

folder.subFolders = [subFolder1, subFolder2]

try! realm.write {
    realm.add(folder)
}