//load data into usersListView private void dataLoader() { //get data from file dbm = new DBmanager(databasePath); FileReader fr = new FileReader(cameFilePath); users = fr.ParseFile().ToArray(); //for every user in the camefile, search entrances in sqlite database foreach (User usr in users) { usr.Entrances = dbm.GetEntrances(usr.Key); } dbm.Close(); //display data usersListView.Items.Clear(); foreach (User usr in users ?? Enumerable.Empty <User>()) { string[] row = { usr.Nome, usr.Key }; ListViewItem listViewItem = new ListViewItem(row); listViewItem.Tag = usr; usersListView.Items.Add(listViewItem); } }