How to convert document to a custom object in Swift 5?

Question

I've been trying to convert the document retrieved from the Firebase's Cloud Firestore to a custom object in Swift 5. I'm following the documentation:

• https://firebase.google.com/docs/firestore/query-data/get-data#custom_objects

However, Xcode shows me the error Value of type 'NSObject' has no member 'data' for the line try $0.data(as: JStoreUser.self). I've defined the struct as Codable.

The code:

func getJStoreUserFromDB() {
    db = Firestore.firestore()
    let user = Auth.auth().currentUser
    db.collection("users").document((user?.email)!).getDocument() { 
        (document, error) in
        let result = Result {
            try document.flatMap {
                try $0.data(as: JStoreUser.self)
            }
        }
    }
}

The user struct:

public struct JStoreUser: Codable {
    let fullName: String
    let whatsApp: Bool
    let phoneNumber: String
    let email: String
    let creationDate: Date?
}

The screenshot:

Does anyone know how to resolve this?

Answer 1

After contacting the firebase team, I found the solution I was looking for. It turns out I have to do import FirebaseFirestoreSwift explicitly instead of just doing import Firebase. The error will disappear after this. (And of course you'll need to add the pod to your podfile first:D)

Answer 2

You can do it as shown below:-

First create model class:-

import FirebaseFirestore
import Firebase

//#Mark:- Users model
struct CommentResponseModel {

    var createdAt : Date?
    var commentDescription : String?
    var documentId : String?

    var dictionary : [String:Any] {
        return [
                "createdAt": createdAt  ?? "",
                "commentDescription": commentDescription  ?? ""
        ]
    }

   init(snapshot: QueryDocumentSnapshot) {
        documentId = snapshot.documentID
        var snapshotValue = snapshot.data()
        createdAt = snapshotValue["createdAt"] as? Date
        commentDescription = snapshotValue["commentDescription"] as? String
    }
}

Then you can convert firestore document into custom object as shown below:-

func getJStoreUserFromDB() {
    db = Firestore.firestore()
    let user = Auth.auth().currentUser
    db.collection("users").document((user?.email)!).getDocument() { (document, error) in
        //        Convert firestore document your custom object
        let commentItem = CommentResponseModel(snapshot: document)
    }
}

Answer 3

You need to initialize your struct and then you can extend the QueryDocumentSnapshot and QuerySnapshot like:

extension QueryDocumentSnapshot {
    func toObject<T: Decodable>() throws -> T {
        let jsonData = try JSONSerialization.data(withJSONObject: data(), options: [])
        let object = try JSONDecoder().decode(T.self, from: jsonData)
        
        return object
    }
}

extension QuerySnapshot {
    
    func toObject<T: Decodable>() throws -> [T] {
        let objects: [T] = try documents.map({ try $0.toObject() })
        return objects
    }
}

Then, try to call the Firestore db by:

db.collection("users").document((user?.email)!).getDocument() { (document, error) in
    guard error == nil else { return }
    guard let commentItem: [CommentResponseModel] = try? document.toObject() else { return }
     // then continue with your code
}

Answer 4

In the past, I had some issues though importing FirebaseFirestore with the package manager in my project. So I explain about the access to FirebaseFirestore in swift.

1. SnapshotListener

    import Foundation
    import FirebaseFirestore
   
    class BooksViewModel: ObservableObject {
      @Published var books = [Book]()
   
      private var db = Firestore.firestore()
   
      func fetchData() {
        db.collection("books").addSnapshotListener { (querySnapshot, error) in
          guard let documents = querySnapshot?.documents else {
            print("No documents")
            return
          }
   
      self.books = documents.map { queryDocumentSnapshot -> Book in
        let data = queryDocumentSnapshot.data()
        let title = data["title"] as? String ?? ""
        let author = data["author"] as? String ?? ""
        let numberOfPages = data["pages"] as? Int ?? 0
   
        return Book(id: .init(), title: title, author: author, numberOfPages: numberOfPages)
         }
       }
     }
   }
   

2. using uid and getDocument function

    Firestore.firestore().collection("users").document(uid).getDocument { snapshot, error in
                    if let error = error {
                        self.errorMessage = "Failed to fetch current user: \(error)"
                        print("Failed to fetch current user:", error)
                        return
                    }
   
                    guard let data = snapshot?.data() else {
                        self.errorMessage = "No data found"
                        return
   
                    }
            let uid = data["uid"] as? String ?? ""
            let email = data["email"] as? String ?? ""
            let profileImageUrl = data["profileImageUrl"] as? String ?? ""
            self.chatUser = ChatUser(uid: uid, email: email, profileImageUrl: profileImageUrl)
    }