firebase childByAutoId.key是可选的

Question

我正在使用Firebase和Swift。 我想使用Firebase函数childByAutoId.key，但无法正常工作。 我做错了什么？ .key是可选的...通常，它必须是非可选的！ 感谢帮助！

import Foundation
import FirebaseDatabase

class AddWatchlistAPI {


    var REF_WATCHLIST = Database.database().reference().child("watchlists")


    static var shared: AddWatchlistAPI = AddWatchlistAPI()
    private init() {
    }

    //add a watchlist to the user
    func addWatchlistToDatabase(watchlistName: String, onSuccess: @escaping () -> Void) {

        let watchlistRef = REF_WATCHLIST
        let watchlistId = watchlistRef.childByAutoId().key //.key is optional ???? --> Normally it isn t optional

        let newWatchlistRef = watchlistRef.child(watchlistId)//here the error is warning

    }

}

Answer 1

尝试如下

1- let watchlistId:String = (watchlistRef.childByAutoId().key)!

要么

2- let watchlistId:String = watchlistRef.childByAutoId().key ?? "" let watchlistId:String = watchlistRef.childByAutoId().key ?? ""

要么

3-

var ref: DatabaseReference!

ref = Database.database().reference()

let llave = self.ref.child(name_of_child).childByAutoId().key