How to move my cursor from one line edit to another line edit using with enter keyword in keyboard

Question

Here is my sample program after i set the text in line edit, i want to change my cursor position one line edit to another line using with keyboard enter key word.Because of this i wrote key press event but this function is executing only for one line edit.Can any one please help me.Thank you in advance.

Given below is my sample code:

import sys
from PyQt4 import QtGui,QtCore

class Example(QtGui.QWidget):

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

        self.initUI()

    def initUI(self):
        box=QtGui.QVBoxLayout(self)
        self.lbl1 = QtGui.QLineEdit()
        self.lbl1.move(15, 10)
        self.lbl2 = QtGui.QLineEdit()
        self.lbl2.move(35, 40)
        self.lbl3 = QtGui.QLineEdit()
        self.lbl3.move(55, 70)
        box.addWidget(self.lbl1)
        box.addWidget(self.lbl2)
        box.addWidget(self.lbl3)

        self.setGeometry(300, 300, 250, 150)
        self.setWindowTitle('Absolute')
        self.show()
    def keyPressEvent(self, event):

        if event.key() == QtCore.Qt.Key_Return:
            if self.lbl1.setFocus():
                self.lbl2.setFocus()

            elif self.lbl2.setFocus():
                self.lbl3.setFocus()
def main():

    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

Answer 1

A possible solution is to use an eventFilter to listen to the events of the widgets, so check if it is the focusWidget applying the logic you indicate:

from PyQt4 import QtCore, QtGui

class Singleton(type(QtCore.QObject), type):
    def __init__(cls, name, bases, dict):
        super(Singleton, cls).__init__(name, bases, dict)
        cls.instance=None

    def __call__(cls,*args,**kw):
        if cls.instance is None:
            cls.instance = super(Singleton, cls).__call__(*args, **kw)
        return cls.instance

class EnterFocusManager(QtCore.QObject): #, metaclass=Singleton):
    __metaclass__ = Singleton

    def __init__(self, parent=None):
        super(EnterFocusManager, self).__init__(parent)
        QtGui.QApplication.instance().installEventFilter(self)
        self._widgets = []

    def eventFilter(self, obj, event):
        if event.type() == QtCore.QEvent.KeyPress and obj == QtGui.QApplication.focusWidget():
            if event.key() == QtCore.Qt.Key_Return:
                f = [(k, v) for k, v in self._widgets if k==obj] 
                if f:
                    f[0][1].setFocus(True)
        return super(EnterFocusManager, self).eventFilter(obj, event)

    @staticmethod
    def setEnterOrder(first, second):
        EnterFocusManager()._widgets.append((first, second))


class Example(QtGui.QWidget):
    def __init__(self):
        super(Example, self).__init__()
        self.initUI()

    def initUI(self):
        box = QtGui.QVBoxLayout(self)
        self.lbl1 = QtGui.QLineEdit()
        self.lbl2 = QtGui.QLineEdit()
        self.lbl3 = QtGui.QLineEdit()
        box.addWidget(self.lbl1)
        box.addWidget(self.lbl2)
        box.addWidget(self.lbl3)

        self.setGeometry(300, 300, 250, 150)
        self.setWindowTitle('Absolute')
        self.show()

        EnterFocusManager.setEnterOrder(self.lbl1, self.lbl2)
        EnterFocusManager.setEnterOrder(self.lbl2, self.lbl3)

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