从 firebase 获取用户数据

Question

I'm currently trying to display the name of the user that is currently logged in, but I can't seem to get it to display the name. Can anyone see what's wrong with the code?

The console was printing the first name of every user so I added in the uuid but now I'm getting a "Use of unresolved identifier 'querySnapshot'" error

func getData() {
        let uuid = UUID().uuidString
        guard let currentUser = Auth.auth().currentUser else { return }
        let dbUsers = Firestore.firestore().collection("members").document(uuid)
        dbUsers.addSnapshotListener { snapshot, error in
        if error != nil {
                 print(error ?? "Couldn't update text field TextUser according to database")
            } else {
                for document in (querySnapshot?.documents)! {
                    if let Name = document.data()["firstName"] as? String {
                        print(Name)
                        var post = NameData(firstname: "")
                        post.firstname = Name

                        self.userName.append(post)
                        self.nameLabel.text = self.name
                    }
                }
                
                print(self.userName)
            }
        }
      }

Answer 1

The error message is telling you that you're using a variable called querySnapshot , but you never defined it.

I suspect you meant to say for document in (snapshot?.documents)! instead.

However, your snapshot is not a QuerySnapshot object, because you're only querying for one document here. So there will be no documents property, and you will have nothing to actually iterate. If you want to query only for a single document, you should use a pattern more like what you see in the documentation for reading a document .

Answer 2

Your query has several mistakes.

1. This is a query for Document and not a collection, so you will be able to retrieve only one document ie the one with the uuid you provided.
2. The placeholder in start of closure for query snapShot is snapshot but in for loop , you used querysnapShot which is an unresolved Identifier as well as querySnapshot.documents doesn't exist in your case.

To retrieve all the data from all the documents, replace your code with following

func getData() {
    let uuid = UUID().uuidString
    guard let currentUser = Auth.auth().currentUser else { return }
    let dbUsers = Firestore.firestore().collection("members")
    dbUsers.addSnapshotListener { snapshot, error in
    if error != nil {
             print(error ?? "Couldn't update text field TextUser according to database")
        } else {
            guard let Snapshot = snapshot else { return }
            for document in (Snapshot.documents) {
                if let Name = document.data()["firstName"] as? String {
                    print(Name)
                    var post = NameData(firstname: "")
                    post.firstname = Name

                    self.userName.append(post)
                    self.nameLabel.text = self.name
                }
            }
            
            print(self.userName)
        }
    }
  }