How to trigger a click event for a push button in second window using PyQt5

Question

I have a main dialog window as shown below

Once the OK button is clicked, second window will open as shown below

I need to trigger the click event of login button frpm the second window. Below is my code. but i doesnt trigger any method.

from .gisedify_support_dialog_login import Ui_Dialog
FORM_CLASS, _ = uic.loadUiType(os.path.join(
os.path.dirname(__file__), 'gisedify_support_dialog_base.ui'))
class GisedifySupportDialog(QtWidgets.QDialog, FORM_CLASS):
 def __init__(self, parent=None):
    """Constructor."""
    super(GisedifySupportDialog, self).__init__(parent)
    # Set up the user interface from Designer through FORM_CLASS.
    # After self.setupUi() you can access any designer object by doing
    # self.<objectname>, and you can use autoconnect slots - see
    # http://qt-project.org/doc/qt-4.8/designer-using-a-ui-file.html
    # #widgets-and-dialogs-with-auto-connect
    self.setupUi(self)

  def open_login_dialog(self):
    Dialog = QtWidgets.QDialog()
    ui = Ui_Dialog()
    ui.setupUi(Dialog)
    Dialog.exec_()
    ui.login_button.clicked.connect(self.login)

  def login(self):
    print('success')

class Login_Dialog(QtWidgets.QDialog,Ui_Dialog):
 def __init__(self, parent=None):
    super(Login_Dialog, self).__init__(parent)

Answer 1

QDialog.exec_() will block until the dialog is closed by the user so you would need to set up any signal-slot connections before you call Dialog.exec_(). When a dialog is closed, it returns 1 when de dialog was accepted, and 0 if not. Closing the dialog does not detroy it (unless you set a flag to do so), so you can retrieve the data that was entered after Dialog.exec_() returns.

So, instead of connecting a slot to the dialog button buttonin the main window, you could instead subclass QDialog, setup the ui using your Qt Designer files, and connect the button.clicked signal to the QDialog.accept slot. Then in the main widget you can call Dialog.exec_() as before and retrieve the information afterwards, e.g.

from PyQt5 import QtWidgets, QtCore, QtGui


class Login_Dialog(QtWidgets.QDialog, Ui_Dialog):
    def __init__(self, parent = None):
        super().__init__(parent)
        self.setupUi(self)
        self.login_button.clicked.connect(self.accept)


class Widget(QtWidgets.QWidget):
    def __init__(self, parent = None):
        super().__init__(parent)
        # setup ui as before

    def get_login(self):
        dialog = Login_Dialog(self)
        if dialog.exec_():
            # get activation key from dialog
            # (I'm assuming here that the line edit in your dialog is assigned to dialog.line_edit)  
            self.activation_key = dialog.line_edit.text()
            self.login()

    def login(self)
        print(f'The activation_key you entered is {self.activation_key}')