swift - 无法从 firebase 实时数据库获取/读取数据到 UITableViewController

Question

我能够成功地将数据从我的应用程序写入我的 firebase 实时数据库。我无法检索数据并将其显示在 UIViewController 中。

我有搜索堆栈、YouTube 和 firebase 文档，但没有运气。我打印出计数并返回 0。我相信 For 循环没有迭代或者它没有正确附加到我的数组。我有 trie 强制包装和解包 refRepairs，并从中放置 databaseHandle。

    override func viewDidLoad() {
    super.viewDidLoad()
    refRepairs = Database.database().reference().child("repairs");

    //observing the data changes
    refRepairs!.child("repairs").observe(DataEventType.value, with: { (snapshot) in

        //if the reference have some values
        if snapshot.childrenCount > 0 {

            //clearing the list
            self.repairList.removeAll()

            //iterating through all the values
            for repairs in snapshot.children.allObjects as! [DataSnapshot] {
                //getting values
                let repairObject = repairs.value as? [String: AnyObject]
                let brand  = repairObject?["brand"]
                let id  = repairObject?["id"]
                let modelNumber = repairObject?["modelNumber"]

                //creating artist object with model and fetched values
                let repair = RepairModel(id: id as! String?, brand: brand as! String?, modelNumber: modelNumber as! String?)

                //appending it to list
                print(snapshot.childrenCount)

                self.repairList.append(repair)
            }

            //reloading the tableview
            self.doListTableView.reloadData()
        }
    })
}

我进行了更改并且它正在运行!!!现在，我尝试通过 uid 向数据库中添加记录，我已经成功地做到了。现在我有同样的问题，我无法显示记录。我打印了计数，它返回了 1 条正确的记录。这是新代码。

    override func viewDidLoad() {
    super.viewDidLoad()
    refRepairs = Database.database().reference().child("repairs");

    //observing the data changes
    //refRepairs!.child("uid").observe(DataEventType.value, with: { (snapshot) in


        //observing the data changes
        refRepairs!.observe(DataEventType.value, with: { (snapshot) in
        //if the reference have some values
        if snapshot.childrenCount > 0 {

            //clearing the list
            self.repairList.removeAll()

            //iterating through all the values
            for repairs in snapshot.children.allObjects as! [DataSnapshot] {
                //getting values
                let repairObject = repairs.value as? [String: AnyObject]
                let brand  = repairObject?["brand"]
                let uid = repairObject?["uid"]
                let id  = repairObject?["id"]
                let modelNumber = repairObject?["modelNumber"]

                //creating artist object with model and fetched values
                let repair = RepairModel(uid: uid as! String?, id: id as! String?, brand: brand as! String?, modelNumber: modelNumber as! String?)

                //appending it to list
                print(snapshot.childrenCount)

                self.repairList.append(repair)
            }

            //reloading the tableview
            self.doListTableView.reloadData()
        }
    })
}

Answer 1

你在“观察数据变化”的时候，正在寻找另一个叫repairs的老二。试试这个:

override func viewDidLoad() {
  super.viewDidLoad()
  refRepairs = Database.database().reference().child("repairs");

  //observing the data changes
  refRepairs!.observe(DataEventType.value, with: { (snapshot) in

    ...

如果那行不通。使用 Firebase 的 observeSingleEvent 方法