How to grab the current users "firstname" from firebase store. Swift 5

Question

I did more trial and error and a bit of online research and this is what I came back with:

func presentWelcomeMessage() {
    
               //Get specific document from current user
               let docRef = Firestore.firestore()
                  .collection("users")
                  .whereField("uid", isEqualTo: Auth.auth().currentUser?.uid ?? "")

               // Get data
               docRef.getDocuments { (querySnapshot, err) in
                   if let err = err {
                       print(err.localizedDescription)
                   } else if querySnapshot!.documents.count != 1 {
                       print("More than one document or none")
                   } else {
                       let document = querySnapshot!.documents.first
                       let dataDescription = document?.data()
                       guard let firstname = dataDescription?["firstname"] else { return }
                       self.welcomeLabel.text = "Hey, \(firstname) welcome!"
                   }
               }

It works, but am not sure if it is the most optimal solution.

Answer 1

First I should say firstname is not really the best way to store a var. I would recommend using firstName instead for readability. I also recommend getting single documents like I am, rather than using a whereField.

An important thing to note is you should create a data model like I have that can hold all of the information you get.

Here is a full structure of how I would get the data, display it, and hold it.

struct UserModel: Identifiable, Codable {
    var id: String
    var firstName: String

    private enum CodingKeys: String, CodingKey {
       case id
       case firstName
    }
}

import SwiftUI
import FirebaseAuth
import FirebaseFirestore
import FirebaseFirestoreSwift

class UserDataManager: ObservableObject {
    private lazy var authRef = Auth.auth()
    private lazy var userInfoCollection = Firestore.firestore().collection("users")
    
    public func getCurrentUIDData(completion: @escaping (_ currentUserData: UserModel) -> Void) {
        if let currentUID = self.authRef.currentUser?.uid {
            self.userInfoCollection.document(currentUID).getDocument { (document, error) in
                if let document = document {
                    if let userData = try? document.data(as: UserModel.self) {
                        completion(userData)
                    }
                } else if let error = error {
                    print("Error getting current UID data: \(error)")
                }
            }
        } else {
            print("No current UID")
        }
    }
}

struct ContentView: View {
    @State private var userData: UserModel? = nil
    private let
    var body: some View {
        ZStack {
            if let userData = self.userData { <-- safely unwrap data
                Text("Hey, \(userData.firstName) welcome!")
            }
        }
        .onAppear {
            if self.userData == nil { <-- onAppear can call more than once
                self.udm.getCurrentUIDData { userData in
                   self.userData = userData  <-- pass data from func to view
                }
            }
        }
    }
}

Hopefully this can point you in a better direction of how you should be getting and displaying data. Let me know if you have any further questions or issues.