PySide: How to have Input Mask and Place Holder Text at the same time

Question

I'm trying to make a lineEdit widget have place holder text (look like 'MM/DD/YYYY') when not in focus and have input masking (looks like ' / / ', or you can put in slashes through other means) when in focus.

Currently the input mask setInputMask('99/99/9999') takes precedence and I can't figure out a way to put a hasFocus (or similiar) signal on a LineEdit widget.

How would you implement both of these functionalities in one widget? Would it be easier to leave the place holder text as is and create a method that adds in a slash after entering a certain number of characters?

Also, the flicking cursor is really thick when you set a mask. What's up with that and how do you revert it?

Full code:

from PySide import QtCore, QtGui

class Ui_MainWindow(object):
    def myChanges(self):
        self.lineEdit.installEventFilter(self.lineEdit.setInputMask('99/99/9999'))
        self.lineEdit.setPlaceholderText('MM/DD/YYYY')

    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(557, 351)
        self.centralwidget = QtGui.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.lineEdit = QtGui.QLineEdit(self.centralwidget)
        self.lineEdit.setGeometry(QtCore.QRect(100, 130, 113, 20))
        self.lineEdit.setObjectName("lineEdit")
        self.lineEdit_2 = QtGui.QLineEdit(self.centralwidget)
        self.lineEdit_2.setGeometry(QtCore.QRect(320, 130, 113, 20))
        self.lineEdit_2.setObjectName("lineEdit_2")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtGui.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 557, 21))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtGui.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

        self.myChanges()

    def retranslateUi(self, MainWindow):
        MainWindow.setWindowTitle(QtGui.QApplication.translate("MainWindow", "MainWindow", None, QtGui.QApplication.UnicodeUTF8))


if __name__ == "__main__":
    import sys
    app = QtGui.QApplication(sys.argv)
    MainWindow = QtGui.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

Answer 1

If you want a custom behavior of a widget you must create a class that inherits from this, in your case of QLineEdit. To get your specific objective you must use the focusInEvent and focusOutEvent methods as described in the following section:

class LineEdit(QtGui.QLineEdit):
    def __init__(self, parent=None):
        QtGui.QLineEdit.__init__(self, parent=parent)
        self.setPlaceholderText('MM/DD/YYYY')

    def focusInEvent(self, event):
        self.setInputMask('99/99/9999')

    def focusOutEvent(self, event):
        self.setInputMask('')

And then you should change to:

self.lineEdit = QtGui.QLineEdit(self.centralwidget)

to:

self.lineEdit = LineEdit(self.centralwidget)