[FIXED] Adding items to QComboBox

Issue

I'm trying to add items to two combo boxes.

The code below runs with no errors, I see the list I'm trying to add and "fin" is printed to the terminal, but the combo boxes are showing up empty.

from PyQt5.QtWidgets import QMainWindow
from PyQt5 import QtWidgets

# import GUI from designer file
from main_menu import Ui_main_menu
# import other functions
from add_functions import ChangeLists


class Main(QMainWindow, Ui_main_menu):
    def __init__(self, parent=None):
        super(Main, self).__init__(parent)
        self.setupUi(self)
        self.init_lists()

    def init_lists(self):
        # Team List
        team_list_file = open(r'C:\NHLdb_pyqt\files\NHLteams.txt', 'r')
        team_list = team_list_file.read().splitlines()
        team_list_file.close()
        print("team list: ", team_list)
        # Initial Player List
        player_list_init = "Please Select a Team"
        # Populate combo box lists
        self.team_select_combobox.addItems(team_list)
        self.player_select_combobox.addItem(player_list_init)
        # connect combo box to function that will change player list based on team list selection
        # self.team_select_combobox.currentTextChanged.connect(ChangeLists.team_changed)
        print("fin")


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    main_menu = QtWidgets.QDialog()
    ui = Main()
    ui.setupUi(main_menu)
    # main_menu = Main()
    main_menu.show()
    sys.exit(app.exec_())

Solution

You're using two methods of loading the ui at the same time, the multiple inheritance approach and the "direct approach", and you're actually showing the main_menu instance of QDialog (which doesn't have any init_lists function).

The result is that even if the init_lists is called, it's "shown" (actually, not) in the wrong window, since you're showing the main_menu instance.

Clearly, you should not use both of them, as the first is enough (and usually the most used/suggested), and then show the correct instance object:

if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    main_menu = Main()
    main_menu.show()
    sys.exit(app.exec_())

Do note that there's something else that is wrong with your implementation: you're inheriting from QMainWindow in the Main class, but later you're trying to set up the ui using a QDialog.

Only the base class created in Designer should be used (it doesn't matter what approach you use to load the ui). I can assume that the ui was created using a QDialog (otherwise an exception would have occurred, as a QMainWindow ui would try to use setCentralWidget() which is a function that doesn't exist for QDialog).

So, you either create a new main window in Designer and copy your existing layout in that (if you need the features of a QMainWindow, such as a menu bar, a status bar, dock widgets or toolbars), or you correctly use the QDialog class in the constructor:

class Main(QDialog, Ui_main_menu):
    # ...

Answered By - musicamante