Toggling button based on global control variables-CodePudding

I'm trying to toggle on/off a button based on the value of control variables (choice1_is_selected & choice2_is_selected), which are defined as global.

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QWidget, QGridLayout, QHBoxLayout, QLabel, QComboBox, QPushButton

class duo(QWidget):
    def __init__(self,text,choice):
        super().__init__()

        layoutC = QHBoxLayout()
        layoutC.addWidget(QLabel(text))
        options=QComboBox()
        options.addItems(choice)
        options.currentTextChanged.connect(self.text_changed)
        layoutC.addWidget(options)
        self.setLayout(layoutC)

    def text_changed(self, s): 
        global choice1_is_selected,choice2_is_selected
        choice1_is_selected = True

class duoB(QWidget):
    def __init__(self,text,choice):
        super().__init__()

        layoutB = QHBoxLayout()
        layoutB.addWidget(QLabel(text))
        options=QComboBox()
        options.addItems(choice)
        options.currentTextChanged.connect(self.text_changed)
        layoutB.addWidget(options)
        self.setLayout(layoutB)

    def text_changed(self, s): 
        global choice1_is_selected,choice2_is_selected
        choice2_is_selected = True

class MainWindow(QWidget):

    def __init__(self):
        super(MainWindow, self).__init__()

        self.setWindowTitle("Reproducible")

        layout = QGridLayout()
        layout.addWidget(QLabel("Block 1"),0,0)
        text2 = 'Block 2'
        select2 = ['Not selected','first','second']
        widgetcomposite1 = duo(text2,select2)
        layout.addWidget(widgetcomposite1,1,0)
        text3 = 'Block 3'
        select3 = ['Unselected','I','II']
        widgetcomposite2 = duoB(text3,select3)
        layout.addWidget(widgetcomposite2,2,0)
        self.btn_download = QPushButton('Download')
        if (choice1_is_selected == True) and (choice2_is_selected == True):
            self.btn_download.setDisabled(False)
        else:
            self.btn_download.setDisabled(True)

        layout.addWidget(self.btn_download,3,0)

        self.setLayout(layout)


app = QApplication(sys.argv)

choice1_is_selected = False
choice2_is_selected = False

window = MainWindow()
window.show()

app.exec()

What is tripping me is that the code seems to check the conditional statement at the start but not later so it never enables the download option.

CodePudding user response：

It doesn't work because your if statement no longer works after execution. You should call that statement again (using signals, calling the function, etc.).

Here is a possible solution that worked for me:

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QWidget, QGridLayout, QHBoxLayout, QLabel, QComboBox, QPushButton

class duo(QWidget):
    def __init__(self,parent, text,choice):
        super().__init__(parent)

        layoutC = QHBoxLayout()
        layoutC.addWidget(QLabel(text))
        options=QComboBox()
        options.addItems(choice)
        options.currentTextChanged.connect(self.text_changed)
        layoutC.addWidget(options)
        self.setLayout(layoutC)

    def text_changed(self):
        global choice1_is_selected,choice2_is_selected
        choice1_is_selected = True
        self.parent().button_is_selected()

class duoB(QWidget):
    def __init__(self,parent,text,choice):
        super().__init__(parent)

        layoutB = QHBoxLayout()
        layoutB.addWidget(QLabel(text))
        options=QComboBox()
        options.addItems(choice)
        options.currentTextChanged.connect(self.text_changed)
        layoutB.addWidget(options)
        self.setLayout(layoutB)

    def text_changed(self):
        global choice1_is_selected,choice2_is_selected
        choice2_is_selected = True
        self.parent().button_is_selected()

class MainWindow(QWidget):

    def __init__(self):
        super(MainWindow, self).__init__()

        self.setWindowTitle("Reproducible")

        layout = QGridLayout()
        layout.addWidget(QLabel("Block 1"),0,0)
        text2 = 'Block 2'
        select2 = ['Not selected','first','second']
        widgetcomposite1 = duo(self, text2,select2)
        layout.addWidget(widgetcomposite1,1,0)
        text3 = 'Block 3'
        select3 = ['Unselected','I','II']
        widgetcomposite2 = duoB(self, text3,select3)
        layout.addWidget(widgetcomposite2,2,0)
        self.btn_download = QPushButton('Download')

        layout.addWidget(self.btn_download,3,0)
        self.setLayout(layout)
        self.button_is_selected()
    def button_is_selected(self):
        if (choice1_is_selected == True) and (choice2_is_selected == True):
            self.btn_download.setDisabled(False)
        else:
            self.btn_download.setDisabled(True)


app = QApplication(sys.argv)

choice1_is_selected = False
choice2_is_selected = False

window = MainWindow()
window.show()

app.exec()