ios - 如何检索 autoId 以删除值

Question

我试图让用户在按下删除按钮时删除评论。当评论被提交时，它们是使用 autoId 创建的，节点的标题将是 postId 以查看他们评论了什么帖子。

  "comments" : {
    "-LmfZZis5ovtBwfm_4xR" : {
      "-LoHu5Qv3BmuHTsSlthj" : {
        "creationDate" : 1.567980283717026E9,
        "text" : "Kkkk",
        "uid" : "64r3dgTN6xMhHYhptFlsFWX0dLk2"
      },
      "-LoHuPohuQ3eUtDWL_G-" : {
        "creationDate" : 1.567980367209054E9,
        "text" : " Ok",
        "uid" : "64r3dgTN6xMhHYhptFlsFWX0dLk2"
      }
    }
  },

我不知道如何检索 autoId，以便当前登录的用户可以删除他们的评论。这是提交的代码

  func didSubmit(for comment: String) {

        guard let uid = Auth.auth().currentUser?.uid else { return }

        print("post id:", self.post?.postId ?? "")

        print("Inserting comment:", comment)


        let postId = self.post?.postId ?? ""
        let values = ["text": comment, "creationDate": Date().timeIntervalSince1970, "uid": uid] as [String : Any]

        Database.database().reference().child("comments").child(postId).childByAutoId().updateChildValues(values) { (err, ref) in

            if let err = err {
                print("Failed to insert comment:", err)
                return
            }

            self.uploadCommentNotificationToServer()

            if comment.contains("@") {
                self.uploadMentionNotification(forPostId: postId, withText: comment, isForComment: true)
            }

            self.containerView.clearCommentTextView()
        }

        }

注释结构

struct Comment {
    var commentId: String!
    let user: User
    var creationDate: Date!
    let text: String
    let uid: String!

    init(commentId: String!,user: User, dictionary: [String: Any]) {
        self.commentId = commentId
        self.user = user
        self.text = dictionary["text"] as? String ?? ""
        self.uid = dictionary["uid"] as? String ?? ""

        if let creationDate = dictionary["creationDate"] as? Double {
            self.creationDate = Date(timeIntervalSince1970: creationDate)
        }

    }

    var post: Post?


    func deleteComment() {
        guard let postId = self.post?.postId else { return }

     let commentsRef = Database.database().reference().child("comments")
        commentsRef.child(postId).child(commentId).removeValue()




    }




}

获取评论的代码

    var comments = [Comment]()

    func fetchComments() {
        guard let postId = self.post?.postId else { return }
        let ref = Database.database().reference().child("comments").child(postId)
        ref.observe(.childAdded, with: { (snapshot) in
             let commentId = snapshot.key
            guard let dictionary = snapshot.value as? [String: Any] else { return }

            guard let uid = dictionary["uid"] as? String else { return }

            Database.fetchUserWithUID(with: uid, completion: { (user) in
                let comment = Comment(commentId: commentId, user: user, dictionary: dictionary)

                self.comments.append(comment)
                self.collectionView?.reloadData()
            })

        }) { (err) in
            print("Failed to observe comments")
        }
    }

谢谢!

Answer 1

要能够删除节点，您必须知道该节点的完整路径。

有两种方法可以知道要删除的产品的 key :

1. 从加载数据的那一刻起，您就将它传递给您的应用。
2. 您有一些其他值，允许您对数据库执行查询以查找键。

第一个选项是最常见的，因为您通常会从数据库中加载数据以将其显示给用户。在那种情况下，您应该“简单地”传递 key显示 value 时的数据.

一旦你有了产品/子节点的键，你就可以删除它:

let postId  = "-LmfZZis5ovtBwfm_4xR"
let commentId  = "-LoHu5Qv3BmuHTsSlthj"
let commentsRef = Database.database().reference().child("comments")
commentsRef.child(postId).child(commentId).removeValue()