从 Firebase Auto ID 检索数据 - Firebase Swift

Question

我想在firebase中捕获我的childByAutoId中的所有值。从本质上讲，它存储了一个人入围的所有项目。然而，我似乎没有捕捉到这一点，我认为这是因为我没有正确地调用快照来考虑自动id。

数据库:

userID
-> Favourited
-> Auto Id
-> itemName: x
-> Auto Id
-> itemName: x
-> Auto Id
-> itemName: x

代码:

func retrieveItems() {

guard let userId = Auth.auth().currentUser?.uid else { return }
let ref = Database.database().reference().child("users/(userId)/Favourited")

ref.observe(.value, with: { (snapshot) in
if snapshot.childrenCount>0 {
self.favUsers.removeAll()
for likes in snapshot.children.allObjects as! [DataSnapshot] {
let likesObject = likes.value as? [String: AnyObject]
let itemName = likesObject!["itemName"]
let likesList = Names(id: likes.key, itemName: itemName as! String?)
self.favUsers.append(likesList)
}
} else {
print("not yet")
}
})
self.favList.reloadData()
}

有没有人看一下，让我知道我可能做错了什么?谢谢你！

Answer 1

这是因为Firebase异步加载数据，而现在你在self.favUsers.append(likesList)运行之前调用reloadData。

对reloadData的调用需要在关闭/完成处理程序中，当数据从Firebase返回时调用:

ref.observe(.value, with: { (snapshot) in
if snapshot.childrenCount>0 {
self.favUsers.removeAll()
for likes in snapshot.children.allObjects as! [DataSnapshot] {
let likesObject = likes.value as? [String: AnyObject]
let itemName = likesObject!["itemName"]
let likesList = Names(id: likes.key, itemName: itemName as! String?)
self.favUsers.append(likesList)
}
self.favList.reloadData() // 👈 Move this here
} else {
print("not yet")
}
})

我还建议您检查一下这些在Firebase中异步数据加载的答案。