如何以通用方法获取 firestore 文档 ID？

Question

i am new to swift and i am trying to implement generic method to fetch data from firestore.

func fetch<T: Codable>(query: Query, completion:@escaping (Result<[T]?, Swift.Error>) -> Void) {

    var dataArray = [T]()

    query.addSnapshotListener { (querySnapshot, error) in

        guard let snapshot = querySnapshot else {
            print("Error fetching snapshots: \(error!)")
            completion(.failure(error!))
            return
        }

        if snapshot.isEmpty {

            completion(.success(nil))
            return
        }

        snapshot.documentChanges.forEach { change in

            var data: T!

            do {
                data = try FirestoreDecoder().decode(T.self, from: change.document.data())

            } catch let error {
                completion(.failure(error))
                return
            }

            if (change.type == .added) {
                //                    print("New data: \(change.document.data())")
                dataArray.append(data)
            }
        }

        completion(.success(dataArray))

    }

but here i don't know how do i get the document id from change.document.data(). please help me out if any one knows. thank you.

Answer 1

Maybe these links can help https://firebase.google.com/docs/reference/swift/firebasefirestore/api/reference/Classes/DocumentChange

https://firebase.google.com/docs/reference/swift/firebasefirestore/api/reference/Classes/QueryDocumentSnapshot

You have the property newIndex in change of type UInt or you can print the content of change.document.data() and see if there is a field with a name corresponding to an id. The data method contains the values of a document on your firestore console.

Then you can access the dictionary item as follows:

change.document().data()["id"] as? Int