更新文档时无限循环 Firebase

Question

I try to update a document in my Cloud Firestore, the function is working nicely on the first tap of the lifecycle of the app, but on the second, the function start and goes into an infinity loop.

I tried .update([Data]) and .set([Data]) they both works on first tap, and goes infinite on the second

func modifyInfoOwner(info: UserInfo){
    let fireStoreDB = Firestore.firestore()
    var documentID = ""
    fireStoreDB.collection("Users").whereField("email", isEqualTo: info.email).addSnapshotListener(includeMetadataChanges: false) { (snapshot, error) in
        if error != nil {
            print(error?.localizedDescription)
        } else {
            if snapshot?.isEmpty != true && snapshot != nil {
                for document in snapshot!.documents {
                    print("| saving info in DB")
                    print("v")
                    print(info)
                    documentID = document.documentID
                    //                        fireStoreDB.collection("Users").document(documentID)
                    fireStoreDB.collection("Users").document(documentID).setData(["adress" : info.adress, "name" : info.name, "phone" : info.phoneNumber, "seatQuantity" : info.seatQuantity, "email" : info.email, "token" : info.token]){ error in
                        if let error = error {
                            print("Data could not be saved: \(error).")
                        } else {
                            print("Data saved successfully!")
                        }
                    }
                }
            }
        }
    }
}

}

Answer 1

You're updating the same document that you're querying for. And since you use addSnapshotListener , the listener stays active after it first gets the data. So when you call setData on a document, your listener gets triggered again, which causes it to setData again, and that's your endless loop.

The solution here is to use getDocuments instead of addSnapshotListener . With getDocuments , you read the data only once, so the update won't trigger it again.

fireStoreDB.collection("Users")
  .whereField("email", isEqualTo: info.email)
  .getDocuments(includeMetadataChanges: false) { (snapshot, error) in
      ...

The rest of your code won't have to change.