[FIXED] Retrieve data from a dialog in the calling window

Issue

I am struggling to retrieve results from a QDialog window and pass them back to the previous window. I want the user to be able to select a value/values, and then once they click okay in the dialog window, it should return them back to the previous window, and pass the text into the byVariables Textbox. The error returns on the line self.procUnivariate.byVariables.setText(item.text()). The error states:

AttributeError: 'ProcUnivariateVariables' object has no attribute 'procUnivariate'

I also tried using a return statement as you can see that is commented out. Unfortunately it seemed like the code got stuck and wasn't moving to the next line as I threw a print statement after and it never printed that line. I need help figuring out how to pass it back to the ProcUnivariate class once the okay button is clicked. Also, if I can figure this out, I'll likely turn the ProcUnivariate Class into a dialog window as well because it should take away the focus from the main window and shouldn't stay open if the main window is closed.

from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QPushButton, QListWidget, QLineEdit, QTextEdit, QGridLayout, QHBoxLayout, QVBoxLayout, QDialog, QSizePolicy, QFileDialog, QTabWidget, QCheckBox
import PyQt5.QtGui as qtg
import glob
import os
from PyQt5.QtCore import Qt, QSettings
import inspect
from PyQt5 import QtCore
import pandas as pd 
import pathlib
import pyreadstat
import json

class ProcUnivariateVariables(QDialog):
    def __init__(self):
        super().__init__()
        
        
        self.procUnivariateByVariables = []
        self.layout = QGridLayout()
        self.setLayout(self.layout)
        self.allVariables = QListWidget()
        self.allVariables.setSelectionMode(3)
        self.variablesSelected = QListWidget()
        self.variablesSelected.setSelectionMode(3)
        self.layout.addWidget(self.allVariables, 1,0, 4, 1)
        self.layout.addWidget(self.variablesSelected, 1, 1, 4, 1)
        self.okButton = QPushButton("Ok")
        self.resetButton = QPushButton("Reset")
        self.cancelButton = QPushButton("Cancel")
        self.layout.addWidget(self.okButton, 1, 2)
        self.layout.addWidget(self.resetButton, 2, 2)
        self.layout.addWidget(self.cancelButton, 3, 2)
        self.addByVariable = QPushButton(">")
        self.removeVariable = QPushButton("<")
        self.layout.addWidget(self.addByVariable, 5, 0)
        self.layout.addWidget(self.removeVariable, 5, 1)
        
        self.button_Connections()
        
        
    def setItems(self, items):
        self.allVariables.clear()
        for item in items:
            self.allVariables.addItem(item)
      
    def add_by_variable(self):
        selected_elements=[item.text() for item in self.allVariables.selectedItems()]
        variableItem = self.variablesSelected.insertItems(self.variablesSelected.count(),selected_elements)
    
    def button_Connections(self):
        self.addByVariable.clicked.connect(self.add_by_variable)
        self.removeVariable.clicked.connect(self.remove_variable)
        self.okButton.clicked.connect(self.okay_clicked)
    
    def remove_variable(self):
      removeVariables = [item.text() for item in self.variablesSelected.selectedItems()]
      self.selectedVariables.takeItems(removeVariables)
      #sourceItem = self.currentSource.takeItem(oldSource)
    
    def okay_clicked(self):
        self.byVariablesSelected = [item.text() for item in self.variablesSelected.selectedItems()]
        #self.procUnivariateByVariables = byVariablesSelected
        print(self.byVariablesSelected)
        self.accept()
        
        #return self.byVariablesSelected
        

        for item in self.byVariablesSelected:
            print(item)
            self.procUnivariate.byVariables.setText(item.text())

class ProcUnivariate(QWidget):
    def __init__(self):
        super().__init__()
        
        self.procUnivariateVariables = None
        
        layout = QGridLayout(self)

        ##Proc Univariate window Widgets
        self.by = QLabel("By")
        self.byVariables = QLineEdit()
        self.byVariableList = QListWidget()
        self.byButton = QPushButton("...")
        self.varLabel = QLabel("Var")
        self.classLabel = QLabel("Class")
        self.freqLabel = QLabel("Freq")
        self.histogramLabel = QLabel("Histogram")
        self.freqBox = QLineEdit()
        self.histBox = QLineEdit()
        self.varBox = QLineEdit()
        self.varButton = QPushButton("...")
        self.sourceLabel = QLabel("Name")
        self.sourceText = QLineEdit()
        self.sourceButton = QPushButton("...")
        self.selectionLabel = QLabel("Selection criteria")
        self.selectionCriteria = QTextEdit()
        self.statisticLabel = QLabel("Output")
        self.statisticSearch = QLineEdit()
        self.statisticList = QListWidget()
        self.statisticList.setSortingEnabled(True)
        self.outputLabel = QLabel("Output Statement")
        self.outputText = QTextEdit()
        self.fileOutputPath = QLineEdit("Output File Path")
        self.runButton = QPushButton("Run")
        self.previewButton = QPushButton("Preview")
        self.okButton = QPushButton("Ok")
        self.resetButton = QPushButton("Reset")
        self.cancelButton = QPushButton("Cancel")
        self.secondWindowConnections()
        
        layout.addWidget(self.by, 1,0,1,1)
        layout.addWidget(self.byVariables, 2, 0, 1, 4)
        layout.addWidget(self.byButton, 2, 5, 1, 1)
        #layout.addWidget(self.byVariableList, 3, 0, 1, 1)
        layout.addWidget(self.freqLabel, 3, 0)
        layout.addWidget(self.freqBox, 4, 0, 1, 4)
        layout.addWidget(self.histogramLabel, 5, 0)
        layout.addWidget(self.histBox, 6, 0, 1, 4)
        layout.addWidget(self.varLabel, 7, 0, 1, 4)
        layout.addWidget(self.varBox, 8, 0)
        layout.addWidget(self.varButton, 8,5)
        layout.addWidget(self.sourceLabel, 1, 6)
        layout.addWidget(self.sourceText, 2, 6, 1, 4)
        layout.addWidget(self.sourceButton, 2, 10)
        layout.addWidget(self.selectionLabel, 3, 6)
        layout.addWidget(self.selectionCriteria, 4, 6, 1, 4)
        layout.addWidget(self.statisticLabel, 5, 6)
        layout.addWidget(self.statisticSearch, 6, 6, 1, 4)
        layout.addWidget(self.statisticList, 7, 6, 3, 4)
        layout.addWidget(self.outputLabel, 10, 6)
        layout.addWidget(self.outputText, 11, 6, 1, 4)
        layout.addWidget(self.runButton, 12, 6)
        layout.addWidget(self.previewButton, 12, 7)
        layout.addWidget(self.okButton, 12, 8)
        layout.addWidget(self.resetButton, 12, 9)
        layout.addWidget(self.cancelButton, 12, 10)
        
        self.setLayout(layout)
     
    def secondWindowConnections(self):   # this had a typo
        self.byButton.clicked.connect(self.show_third_window)

    def show_third_window(self):
        if self.procUnivariateVariables is None:           # if window has been created yet
            self.procUnivariateVariables = ProcUnivariateVariables()   # create window
        if not self.procUnivariateVariables.isVisible():   # if window is showing
            self.procUnivariateVariables.show()            # show window
        self.procUnivariateVariables.setItems(self.procUnivariateVariablesItems)  # send items to window

    def send_items(self, items):       # this is to collect the variable that
        self.procUnivariateVariablesItems = items  # move to the third window

class MainWindow(QWidget):
    def __init__(self):
        super().__init__()
        # Add a title
        self.setWindowTitle("GUI Querying Program")
        self.layout = QHBoxLayout()
        self.setLayout(self.layout)
        self.initUI()
        self.setButtonConnections()
        self.sw = None    # dont initialize until neccessary.

    def initUI(self):
        subLayouts = {}
        subLayouts['LeftColumn'] = QGridLayout()
        self.layout.addLayout(subLayouts['LeftColumn'],1)
        self.buttons = {}
        self.buttons['addVariable'] = QPushButton('>')
        self.buttons['removeVariable'] = QPushButton('<')
        self.buttons['Toolkit'] = QPushButton('Toolkit')
        self.variables = QListWidget()
        self.selectedVariables = QListWidget()
        subLayouts['LeftColumn'].addWidget(self.variables, 7,0,4,1)
        subLayouts['LeftColumn'].addWidget(self.selectedVariables, 7,1,4,1)
        subLayouts['LeftColumn'].addWidget(self.buttons['addVariable'], 10,0,1,1)
        subLayouts['LeftColumn'].addWidget(self.buttons['removeVariable'], 10,1,1,1)
        subLayouts['LeftColumn'].addWidget(self.buttons['Toolkit'], 11,1,1,1)
        names = ['apple', 'banana', 'Cherry']
        self.variables.insertItems(0, names)

    def setButtonConnections(self):
        self.buttons['addVariable'].clicked.connect(self.add_variable)
        self.buttons['Toolkit'].clicked.connect(self.show_new_window)
        # self.buttons['Toolkit'].clicked.connect(self.add_selected_variables)
        # only use one connnect slot

    def add_variable(self):
        for item in self.variables.selectedItems():
            self.selectedVariables.addItem(item.clone())

    def show_new_window(self):     
        if self.sw is None:   #  check if window has been constructed
            self.sw = ProcUnivariate()  # construct window
        if not self.sw.isVisible():    #  If winow is not showing
            self.sw.show()         #  show window
        self.sw.send_items(self.add_selected_variables())   # send selected 
                                                            # variables to second window

    def add_selected_variables(self):
        items = []
        for i in range(self.selectedVariables.count()):
            items.append(self.selectedVariables.item(i).clone())
        # self.tw.setItems(items) ...  self.tw doesnt exist so return them
        return items 

if __name__ == "__main__":
    import sys
    app = QApplication([])
    mw = MainWindow()
    mw.show()
    app.exec()

Solution

What you need to do is connect a slot to the accepted signal of the dialog, and then retrieve the variables via a dedicated method of the dialog when that signal is emitted.

Here are all the relevant changes (fully tested as working):

class ProcUnivariateVariables(QDialog):
    ...
    def button_Connections(self):
        ...
        # connect to the dialog's built-in accept slot
        self.okButton.clicked.connect(self.accept)
    
    # add a method for retrieving the variables
    def byVariablesSelected(self):
        return [item.text() for item in self.variablesSelected.selectedItems()]

class ProcUnivariate(QWidget):
    ...
    def secondWindowConnections(self):   # this had a typo
        self.byButton.clicked.connect(self.show_third_window)
        self.varButton.clicked.connect(self.show_third_window)

    def show_third_window(self):
        if self.procUnivariateVariables is None:           # if window has been created yet
            self.procUnivariateVariables = ProcUnivariateVariables()   # create window
            # connect the new slot to the dialog's built-in accepted signal
            self.procUnivariateVariables.accepted.connect(self.receive_selected_variables)
        if not self.procUnivariateVariables.isVisible():   # if window is showing
            self.procUnivariateVariables.show()            # show window
        self.procUnivariateVariables.setItems(self.procUnivariateVariablesItems)  # send items to window
        # set an identifier from the source button
        self.procUnivariateVariables.sourceName = self.sender().text()

    # add a slot for handling the dialog's accepted signal
    def receive_selected_variables(self):
        variables = self.procUnivariateVariables.byVariablesSelected()
        text = ', '.join(variables)
        if self.procUnivariateVariables.sourceName == 'byButton':
            self.byVariables.setText(text)
        else:
            self.varBox.setText(text)

(Note that the above changes make the okay_clicked method of ProcUnivariateVariables redundant, so it should be removed).

Answered By - ekhumoro