努力通过 Firestore 传递单个文档 - Swift

Question

Here is my customer class:

class Customer {
    // Creating a customer
    let name: String
    let surname: String
    let contactNo: String
    let email: String
   
    init(name: String,surname: String,contactNo: String,email: String) {
        
        self.name = name
        self.surname = surname
        self.contactNo = contactNo
        self.email = email
    }
}

This is the code I'm using which keeps returning a nil:

class ProfileCus: UIViewController {
    // Labels to display data
    @IBOutlet weak var nameLabel: UILabel!
    @IBOutlet weak var surnameLabel: UILabel!
    @IBOutlet weak var emailLabel: UILabel!
    @IBOutlet weak var contactLabel: UILabel!
    
    // Reference to customer collection in Firestore
    private var  customerRefCollection = Firestore.firestore().collection("customers")
    
    // Customer Object
    private var customer =  Customer(name: "a",surname: "a",contactNo: "a",email: "a")
    
    
    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
         getDataFromFirebase{
               self.customerRefCollection = Firestore.firestore().collection("customers")
                
               print(self.customer,"debug step 5")
               self.nameLabel.text = self.customer.name
               self.surnameLabel.text = self.customer.surname
               self.emailLabel.text = self.customer.email
               self.contactLabel.text = self.customer.contactNo
           }
    }
    
    func getDataFromFirebase(completion:@escaping() -> ()){
                    print(self.customer,"debug step 1")
                    let userID = Auth.auth().currentUser?.uid
                    print(userID,"debug step 2")
                // Locate the user information on Firestore
                    customerRefCollection.document(userID!).getDocument { (snapshot, error) in
                    if let err = error {
                        debugPrint("Error fetching documents: \(err)")
                    }
                    else {
                        // Ensure that if there's nothing in the document that the function returns
                    guard let snap = snapshot else {return}
                    print(snap, "debug step 3")
                    // Parse the data to the customer model
                    let data = snap.data()
                    
                    let name = data?["name"] as? String ?? ""
                    let surname = data?["surname"] as?  String ?? ""
                    let email = data?["email"] as? String ?? ""
                    let contact = data?["contact no"] as? String ?? ""
                    // Create the customer and pass it to the global variable
                    let cus = Customer(name: name, surname: surname, contactNo: contact, email: email)
                    print(self.customer,"debug step 4")
                    self.customer = cus
                }
                    completion()
            }
    }
}

Can anyone please help me understand what I am doing wrong because the snapshot does return but the way I parse the data is wrong because the customer object returns a nil.

I have added print statements with tags saying debug step 1 ect so you can follow what happens at run time, here is the output:

020-08-13 21:15:20.388052+0200 Clean Wheels[8599:430648] 6.29.0 - [Firebase/Analytics][I-ACS023012] Analytics collection enabled Customer(name: "a", surname: "a", contactNo: "a", email: "a") debug step 1 Optional("RWVTDIUuL1eahOLpZT1UmMl0cja2") debug step 2 <FIRDocumentSnapshot: 0x6000017499f0> debug step 3 Customer(name: "a", surname: "a", contactNo: "a", email: "a") debug step 4 Customer(name: "", surname: "", contactNo: "", email: "") debug step 5

It seems to me as if the data function is not the correct function to use because when I hard code the values its shows up in the UI Profile View, is there perhaps an alternative?

Output once the code runs

Answer 1

There are a number of ways you can do this but what I'd suggest is passing the customer object through the completion handler (to the caller). You could also configure the customer object to take the document snapshot in its initializer (instead of taking 4 separate properties) and either return a customer object or nil (this would require a failable intializer which is incredibly basic). Also, I didn't see a need to declare so many instance properties (in this example, anyway) so I took them out. I also made the customer number an integer, not a string (to illustrate how I would structure the data).

class Customer {
    let name: String
    let surname: String
    let contactNo: Int // change this back to a string
    let email: String
   
    init(name: String, surname: String, contactNo: Int, email: String) {
        self.name = name
        self.surname = surname
        self.contactNo = contactNo
        self.email = email
    }
}

class ProfileCus: UIViewController {
    @IBOutlet weak var nameLabel: UILabel!
    @IBOutlet weak var surnameLabel: UILabel!
    @IBOutlet weak var emailLabel: UILabel!
    @IBOutlet weak var contactLabel: UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        getCustomer { (customer) in
            if let customer = customer {
                print(customer)
            } else {
                print("customer not found")
            }
        }
    }
    
    private func getCustomer(completion: @escaping (_ customer: Customer?) -> Void) {
        guard let userID = Auth.auth().currentUser?.uid else {
            completion(nil)
            return
        }
        Firestore.firestore().collection("customers").document(userID).getDocument { (snapshot, error) in
            if let doc = snapshot,
                let name = doc.get("name") as? String,
                let surname = doc.get("surname") as? String,
                let contact = doc.get("contact") as? Int, // cast this as a string
                let email = doc.get("email") as? String {
                let customer = Customer(name: name, surname: surname, contactNo: contact, email: email)
                completion(customer)
            } else {
                if let error = error {
                    print(error)
                }
                completion(nil)
            }
        }
    }
}