[FIXED] Navigate between pages using QStackedLayout

Issue

I'm making a multipage application in which I require to navigate between pages using QStackedLayout. I've made two buttons Previous and Next to navigate.

The problem is that the buttons stop functioning after 2-3 clicks. I guess it's got something to do with the way I'm trying to retrieve the value of CurrentIndex() in the if statement.

import sys
from PyQt5 import QtCore, QtGui, QtWidgets


class Window(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Window, self).__init__(parent)

        self.frame = QtWidgets.QFrame()
        self.stack_lay = QtWidgets.QStackedLayout()

        cam_widget = Page1(self)
        self.stack_lay.addWidget(cam_widget)
        self.stack_lay.setCurrentWidget(cam_widget)
        self.frame.setLayout(self.stack_lay)
        
        self.previous = QtWidgets.QPushButton('Previous')
        self.previous.clicked.connect(self.previous_page)
        self.previous.setDisabled(True)
        self.next = QtWidgets.QPushButton('Next')
        self.next.clicked.connect(self.next_page)

        layout = QtWidgets.QVBoxLayout()
        layout.addWidget(self.frame)
        layout.addWidget(self.previous)
        layout.addWidget(self.next)
        self.setLayout(layout)

    def previous_page(self):
        if self.stack_lay.currentIndex() == 1:
            page1_widget = Page1(self)
            self.stack_lay.addWidget(page1_widget)
            self.stack_lay.setCurrentWidget(page1_widget)
            self.previous.setDisabled(True)
            self.next.setDisabled(False)

        elif self.stack_lay.currentIndex() == 2:
            page2_widget = Page2(self)
            self.stack_lay.addWidget(page2_widget)
            self.stack_lay.setCurrentWidget(page2_widget)
            self.previous.setDisabled(False)
            self.next.setDisabled(False)

    def next_page(self):
        if self.stack_lay.currentIndex() == 0:
            page2_widget = Page2(self)
            self.stack_lay.addWidget(page2_widget)
            self.stack_lay.setCurrentWidget(page2_widget)
            self.previous.setDisabled(False)
            self.next.setDisabled(False)
        
        elif self.stack_lay.currentIndex() == 1:
            page3_widget = Page3(self)
            self.stack_lay.addWidget(page3_widget)
            self.stack_lay.setCurrentWidget(page3_widget)
            self.previous.setDisabled(False)
            self.next.setDisabled(True)

class Page1(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Page1, self).__init__(parent)
        label = QtWidgets.QLabel('Page 1')
        lay = QtWidgets.QVBoxLayout()
        lay.addWidget(label)
        self.setLayout(lay)

class Page2(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Page2, self).__init__(parent)
        label = QtWidgets.QLabel('Page 2')
        lay = QtWidgets.QVBoxLayout()
        lay.addWidget(label)
        self.setLayout(lay)

class Page3(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Page3, self).__init__(parent)
        label = QtWidgets.QLabel('Page 3')
        lay = QtWidgets.QVBoxLayout()
        lay.addWidget(label)
        self.setLayout(lay)


if __name__ == '__main__':
    app = QtWidgets.QApplication([])

    window = Window()
    window.show()

    sys.exit(app.exec_())

Solution

import sys
from PyQt5 import QtCore, QtGui, QtWidgets


class Window(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Window, self).__init__(parent)

        self.frame = QtWidgets.QFrame()
        self.stack_lay = QtWidgets.QStackedLayout()

        self.page1_widget = Page1(self)
        self.page2_widget = Page2(self)
        self.page3_widget = Page3(self)
        self.stack_lay.addWidget(self.page1_widget)
        self.stack_lay.addWidget(self.page2_widget)
        self.stack_lay.addWidget(self.page3_widget)
        self.stack_lay.setCurrentWidget(self.page1_widget)
        self.frame.setLayout(self.stack_lay)
        
        self.previous = QtWidgets.QPushButton('Previous')
        self.previous.clicked.connect(self.previous_page)
        self.previous.setDisabled(True)
        self.next = QtWidgets.QPushButton('Next')
        self.next.clicked.connect(self.next_page)

        layout = QtWidgets.QVBoxLayout()
        layout.addWidget(self.frame)
        layout.addWidget(self.previous)
        layout.addWidget(self.next)
        self.setLayout(layout)

    def previous_page(self):
        if self.stack_lay.currentIndex() == 1:
            self.stack_lay.setCurrentWidget(self.page1_widget)
            self.previous.setDisabled(True)
            self.next.setDisabled(False)

        elif self.stack_lay.currentIndex() == 2:
            self.stack_lay.setCurrentWidget(self.page2_widget)
            self.previous.setDisabled(False)
            self.next.setDisabled(False)

    def next_page(self):
        if self.stack_lay.currentIndex() == 0:
            self.stack_lay.setCurrentWidget(self.page2_widget)
            self.previous.setDisabled(False)
            self.next.setDisabled(False)
        
        elif self.stack_lay.currentIndex() == 1:
            self.stack_lay.setCurrentWidget(self.page3_widget)
            self.previous.setDisabled(False)
            self.next.setDisabled(True)

class Page1(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Page1, self).__init__(parent)
        label = QtWidgets.QLabel('Page 1')
        lay = QtWidgets.QVBoxLayout()
        lay.addWidget(label)
        self.setLayout(lay)

class Page2(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Page2, self).__init__(parent)
        label = QtWidgets.QLabel('Page 2')
        lay = QtWidgets.QVBoxLayout()
        lay.addWidget(label)
        self.setLayout(lay)

class Page3(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Page3, self).__init__(parent)
        label = QtWidgets.QLabel('Page 3')
        lay = QtWidgets.QVBoxLayout()
        lay.addWidget(label)
        self.setLayout(lay)


if __name__ == '__main__':
    app = QtWidgets.QApplication([])

    window = Window()
    window.show()

    sys.exit(app.exec_())

Answered By - Voldemort