public TodoListViewModel()
{
TodoItemViewModel = new TodoItemViewModel();
AddCommand = new RelayCommand(Add, CanAdd);
CompleteCommand = new RelayCommand <TodoItemViewModel>(Complete, CanComplete);
SyncCommand = new RelayCommand(Sync, CanSync);
}
async void Complete(TodoItemViewModel todoItemViewModel)
{
try
{
Locator.Instance.IsBusy = true;
// Mark todo item as done which raises INPC event so UI can react appropriately
todoItemViewModel.Done = true;
// Update the database to reflect the completed state
await Locator.Instance.TodoItemTable.UpdateAsync(todoItemViewModel.TodoItem);
// If connected then push changes to server but it won't pull any server updates
if (Locator.Instance.IsSyncEnabled && await Locator.Instance.IsConnected())
{
await Locator.Instance.PushChanges();
}
// Pause so UI can briefly show the checkmark
await Task.Delay(250);
// Delete item from the bound ViewModel to keep it in sync and so ObservableCollection
// raises INPC which updates ListView to reflect deleted item
Locator.Instance.TodoItems.Remove(todoItemViewModel);
// If we don't pause here the ResetUI will effectively be ignored because it runs
// asychonously with the previous ListView.Remove() and will complete before it
await Task.Delay(225);
// Reset UI in preparation for subsequent entries
Messenger.Default.Send <ResetUI>(new ResetUI());
}
catch (Exception e)
{
// Something went wrong so rollback changes to ViewModel
todoItemViewModel.Done = false;
Messenger.Default.Send <PersistanceException>(new PersistanceException {
Exception = e
});
}
finally
{
Locator.Instance.IsBusy = false;
}
}
bool CanComplete(TodoItemViewModel todoItem)
{
return(true);
}