ios - 追加 RLMArray 时出现问题，更新 RLMObject 中的 RLMArray 并将其与 swift Realm 3.0 中的对象链接

Question

想要一些方法来更新现有的关注者，如果不存在，请将其添加到数据库并将它们链接到用户，例如

GETS CRASH OVER append in write block，由于主键重复，此外，如果没有在 HKUser 表中添加关注者，它会完美运行，一旦更新它就会崩溃

import UIKit
import RealmSwift
class HKUser: Object{
    dynamic var full_name = ""
    dynamic var email: String?
    dynamic var user_id: String?
    let followers = List<HKUser>()

    override static func primaryKey() -> String? {
        return "user_id"
    }
}

我也想更新数据库中用户的连接，所以我想做一些类似的事情

//1. updated the userFollower array with required data
let userFollowers:[HKUser] = []

//2. now need to link it with my user object and update it in db
if let user = realmWrapper.sharedInstance.getUser(forID: id) {
    try! realm.write {
        //want some method like which do update the existing followers,
        //and if not exists do add it to db and link them to user something like
        //realm.add(user, update: true)

        user.followers.append(contentsOf: followers)
        /**********
         GETS CRASH OVER HERE,
         due to duplicate primary key,
         it works perfect if no followers has been added in HKUser Table,
         once it comes to update it crashes
         **********/
    }
}

Answer 1

List<T>.append()如果对象是非托管的，则方法隐式保存到 Realm。这就是为什么会出现重复主键异常的原因。

为避免这种情况，您可以在附加到列表之前添加或更新非托管对象。然后将对象附加到列表中。

try! realm.write {
    ...
    realm.add(followers, update: true) // Add or update the objects first
    user.followers.append(contentsOf: followers)
    ...
}