问题
Sorry if this is a very basic question, but I'm looking to fetch a userId from one Firebase table and use that userId to pull data from another Firebase table. In the first function, I call a fetchUserData function to get the firstname of my user based on a given userid. I'm able to pull the firstname, but then how do I return it to my first function so that I can insert it in the append method.
func fetchList() {
let currentUser = Auth.auth().currentUser!
let postRef = self.databaseRef.child("List").child(currentUser.uid)
postRef.observe(.value, with: { (snapshot) in
for childSnapshot in snapshot.children.allObjects as! [DataSnapshot] {
let userid = childSnapshot.key
self.fetchUserData(uid: userid)
self.userArray.append(User(firstname: "Need to get from fetchUserData", uid: userid))
self.tableView.reloadData()
}
})
}
func fetchUserData(uid: String){
let currentUserRef = databaseRef.child("users").child(uid)
currentUserRef.observeSingleEvent(of: .value, with: { (snapshot) in
//fetch firstname based on given uid
let value = snapshot.value as? NSDictionary
let firstname = value?["firstname"] as? String ?? ""
})
}
回答1:
You can use like this:
func fetchList() {
let currentUser = Auth.auth().currentUser!
let postRef = self.databaseRef.child("List").child(currentUser.uid)
postRef.observe(.value, with: { (snapshot) in
for childSnapshot in snapshot.children.allObjects as! [DataSnapshot] {
let userid = childSnapshot.key
self.fetchUserData(uid: userid, callback: { (firstName) in
self.userArray.append(User(firstname: firstName, uid: userid))
self.tableView.reloadData()
})
}
})
}
func fetchUserData(uid: String, callback: @escaping (_ firstname: String)->Void){
let currentUserRef = databaseRef.child("users").child(uid)
currentUserRef.observeSingleEvent(of: .value, with: { (snapshot) in
//fetch firstname based on given uid
let value = snapshot.value as? NSDictionary
let firstname = value?["firstname"] as? String ?? ""
callback(firstname)
})
}
来源：https://stackoverflow.com/questions/46534571/fetch-user-info-and-append-to-an-array