如何将组合框中的选定元素保存为 PyQt5 中的变量？

Question

I'm interested in how to save a selected value from my combobox as variable, so when I press eg B then I want it to be saved as SelectedValueCBox = selected value, which would be B in this case. Thank you for your help

from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
import sys

class App(QMainWindow): 
    def __init__(self): 
        super().__init__() 
        self.title = "PyQt5 - StockWindow"
        self.left = 0
        self.top = 0
        self.width = 200
        self.height = 300
        self.setWindowTitle(self.title) 
        self.setGeometry(self.left, self.top, self.width, self.height) 
        self.tab_widget = MyTabWidget(self) 
        self.setCentralWidget(self.tab_widget) 
        self.show() 

class MyTabWidget(QWidget): 
    def __init__(self, parent): 
        super(QWidget, self).__init__(parent) 
        self.layout = QVBoxLayout(self)
        #self.layout = QGridLayout(self) 
        self.tabs = QTabWidget() 
        self.tab1 = QWidget() 
        self.tabs.resize(300, 200) 
        self.tabs.addTab(self.tab1, "Stock-Picker") 
        self.tab1.layout = QGridLayout(self)

        button = QToolButton()
        self.tab1.layout.addWidget(button, 1,1,1,1)

        d = {'AEX':['A','B','C'], 'ATX':['D','E','F'], 'BEL20':['G','H','I'], 'BIST100':['J','K','L']}

        def callback_factory(k, v):
           return lambda: button.setText('{0}_{1}'.format(k, v))

        menu = QMenu()
        self.tab1.layout.addWidget(menu, 1,1,1,1)
        for k, vals in d.items():
            sub_menu = menu.addMenu(k)
            for v in vals:
                action = sub_menu.addAction(str(v))
                action.triggered.connect(callback_factory(k, v))
            button.setMenu(menu)
      
        self.tab1.setLayout(self.tab1.layout)
        self.layout.addWidget(self.tabs)
        self.setLayout(self.layout)
if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = App()
    sys.exit(app.exec_())

Answer 1

Since you're already returning a lambda for the connection, the solution is to use a function instead.

class MyTabWidget(QWidget):
    def __init__(self, parent):
        # ...
        def callback_factory(k, v):
            def func():
                self.selectedValueCBox = v
                button.setText('{0}_{1}'.format(k, v))
            return func

        # ...
        self.selectedValueCBox = None

Note that your code also has many issues.

First of all, you should not add the menu to the layout: not only it doesn't make any sense (the menu should pop up, while adding it to a layout makes it "embed" into the widget, and that's not good), but it also creates graphical issues especially because you added the menu to the same grid "slot" (1, 1, 1, 1) which is already occupied by the button.

Creating a layout with a widget as argument automatically sets the layout to that widget. While in your case it doesn't create a big issue (since you've already set the layout) you should not create self.tab1.layout with self . Also, since you've already set the QVBoxLayout (due to the parent argument), there's no need to call setLayout() again.

A widget container makes sense if you're actually going to add more than one widget. You're only adding a QTabWidget to its layout, so it's almost useless, and you should just subclass from QTabWidget instead.

Calling resize on a widget that is going to be added on a layout is useless, as the layout will take care of the resizing and the previous resize call will be completely ignored. resize() makes only sense for top level widgets (windows) or the rare case of widgets not managed by a layout.

self.layout() is an existing property of all QWidgets, you should not overwrite it. The same with self.width() and self.height() you used in the App class.

App should refer to an application class, but you're using it for a QMainWindow. They are radically different types of classes.

Finally, you have no combobox in your code. A combobox is widget that is completely different from a drop down menu like the one you're using. I suggest you to be more careful with the terminology in the future, otherwise your question would result very confusing, preventing people to actually being able to help you.