python - Trying to take a value from a dictionary of a ComboBox and instert the key in a textEdit

Question

I have a dictionary and a ComboBox that shows dictionary's values, i need to print in a textEdit the key of the dictionary's value chosen by the user. Here's my code.

import sys
from PyQt5.QtCore import pyqtSlot
from PyQt5.QtWidgets import QApplication, QDialog, QMainWindow
from PyQt5.uic import loadUi
from math import pi

class MainPage(QMainWindow):

    classi = {None : None, "C25/30" : float(14.17), 
        "C28/35" : float(15.87), "C32/40" : float(18.13), 
        "C35/45" : float(19.83), "C40/50" : float(22.6),
        "C45/55" : float(25.5), "C50/60" : float(28.3)}

    Acciaio = {None : None, "B450C" : float(391.3)}

    Ferri = {14 : float(1.54), 16 : float(2.01),
         18 : float(2.54), 20 : float(3.14), 22 : float(3.8)}

    N = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

    def __init__(self):
        super(MainPage, self).__init__()
        loadUi('Concrete.ui', self)
        x = self.fillCombobox()
        y = self.fillCombobox_2()
        z = self.fillCombobox_3()
        v = self.fillCombobox_4()
        w = self.fillCombobox_5()
        a = self.fillCombobox_6()
        b = self.fillCombobox_7()
        c = self.fillCombobox_8()


    def fillCombobox(self):
        for i in self.classi:
            self.comboBox.addItem(i)


    def fillCombobox_2(self):
        for i in self.Acciaio:
            self.comboBox_2.addItem(i)

    def retrieveText(self):
        x = self.comboBox.currentData()
        self.textEdit.setText(x)


app = QApplication(sys.argv)
widget = MainPage()
widget.show()
sys.exit(app.exec_())

I know that the function retrieveText doesn't make what i want but it was a try and also this doesn't give any output.

Answer 1

You have to save the values associated with the keys through itemData and obtain it when an item is selected.

class MainPage(QMainWindow):

    classi = {
        None: None,
        "C25/30": 14.17,
        "C28/35": 15.87,
        "C32/40": 18.13,
        "C35/45": 19.83,
        "C40/50": 22.6,
        "C45/55": 25.5,
        "C50/60": 28.3,
    }

    def __init__(self):
        super(MainPage, self).__init__()
        loadUi("Concrete.ui", self)
        self.comboBox.currentIndexChanged[int].connect(self.retrieveText)
        self.fillCombobox()

    def fillCombobox(self):
        for key, value in self.classi.items():
            self.comboBox.addItem(key, value)

    @pyqtSlot(int)
    def retrieveText(self, index):
        x = self.comboBox.itemData(index)
        if x is not None:
            self.textEdit.setText(str(x))