Python: How to enable button if the QlineEdit is Filled

Question

Can someone tell me what approach or what logic so the QPushbutton will be enable if all the fields are not empty. I'm making a simple form that you can only push the button if the fields are not empty.

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(392, 232)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.lineEdit = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit.setGeometry(QtCore.QRect(140, 60, 113, 20))
        self.lineEdit.setObjectName("lineEdit")
        self.lineEdit_2 = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit_2.setGeometry(QtCore.QRect(140, 90, 113, 20))
        self.lineEdit_2.setObjectName("lineEdit_2")
        self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(100, 60, 47, 13))
        self.label.setObjectName("label")
        self.label_2 = QtWidgets.QLabel(self.centralwidget)
        self.label_2.setGeometry(QtCore.QRect(100, 90, 47, 13))
        self.label_2.setObjectName("label_2")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setEnabled(False)
        self.pushButton.setGeometry(QtCore.QRect(300, 170, 75, 23))
        self.pushButton.setObjectName("pushButton")
        MainWindow.setCentralWidget(self.centralwidget)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

This is a sample code.

Answer 1

You have to connect the textChanged signals to a slot where you verify the condition required to enable or disable the button:

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        # ...

class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.setupUi(self)
        self.lineEdit.textChanged.connect(self.on_text_changed)
        self.lineEdit_2.textChanged.connect(self.on_text_changed)

    @QtCore.pyqtSlot()
    def on_text_changed(self):
        self.pushButton.setEnabled(bool(self.lineEdit.text()) and bool(self.lineEdit_2.text()))

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.show()
    sys.exit(app.exec_())