Firebase reads the wrong data

Question

Hello

I have my notebooksPage, witch read all my notebooks, but when I navigate to my Notes page, for some reason it read the notebooks again, this is becouse on inheritance

NotebookPageModel

  public async virtual void SeletedItemActionAsync() {  
  
            if (SelectedNotebook != null) {  
  
                NotesPage notesPage = new NotesPage();  
                Application.Current.Properties["id"] = SelectedNotebook.Id;  
                await Application.Current.MainPage.Navigation.PushAsync(notesPage, true);      
                SelectedNotebook = null;  
            }  
        }  

Here I m passing the selected Notobook selected id to the NotesPage model

NotesPageModel

 public class NotesPageModel : NotebooksPageModel {  
  
        public string NotebookId { get; set; }  
  
        public Note SeletedNote { get; set; }  
  
        public Command<Note> DeleteNoteCommand { get; set; }  
  
        public Command PageDisappearCommand { get; set; }  
  
        public NotesPageModel() {  
  
            DeleteNoteCommand = new Command<Note>(DeleteNoteAction);  
  
            FabAnimationCommmand = new Command<Frame>(AnimateButtonCommand);  
  
           // PageDisappearCommand = new Command(PageDisappearAction);  
        }  
  
  
  
        public override async void AppearAction() {  
            base.AppearAction();  
  
            NotebookId = Application.Current.Properties["id"] as string;  
  
            Console.WriteLine($"NotebookID {NotebookId}");  
  
            FireBaseNotebookNotes = await App.FirebaseServices.ReadAsync(AppConstant.Notes, NotebookId);  
  
        }  

          

This method fires every time the page appears, and I can verify I have the ID

ReadAsync

      public async Task<ObservableCollection<NotebookNote>> ReadAsync(string ChildName, string NotebookId = "") {  
  
            var list = await firebaseClient.Child(ChildName)  
                 .OnceAsync<NotebookNote>();  
  
            var collection = new List<NotebookNote>();  
  
            foreach (var item in list) {  
                NotebookNote notebookNote = null;  
                notebookNote = Convert(ChildName, item);  
                collection.Add(notebookNote);  
            }  
  
            if (ChildName.Equals(AppConstant.Notes)) {  
                collection = collection.Where(n => ((Note)n).NotebookId == NotebookId).ToList();  
            } else {  
                collection = collection.Where(n => n.UserID == Preferences.Get(AppConstant.UserID, string.Empty)).ToList();  
            }  
            FireBaseNotebooks.Clear();  
            foreach (var element in collection) {  
                FireBaseNotebooks.Add(element);  
            }  
  
            return FireBaseNotebooks;  
        }  

https://github.com/eduardoagr/DuoNotes

Answer 1

Hello,​

I debug your application, When I navigate the NotesPage, await App.FirebaseServices.ReadAsync(AppConstant.Notes, NotebookId); method will be executed twice.

I can get the correct result at the first time, but I get the wrong result at the second time.

So, I remove the base.AppearAction(); in the AppearAction method of NotesPageModel.cs, the result the correct. Because your NotesPageModel extend NotebooksPageModel, and you will execute the NotebooksPageModel's AppearAction again.

Best Regards,

Leon Lu

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