Python PyQt Creating comboboxes depending on the number user selected on spinbox

Question

My objective is to give the user QComboBoxes depending on the number he/she selected on the QSpinbox.

So, it will be something like this:

User will select a number on QSpinbox,after that, by using the signal valueChanged(int) i want to invoke another function that will create QComboBoxes for user to enter the data.

As soon as user change to another value. It will automatically increase / decrease the QComboBox numbers depending on the QSpinbox value.

So i came up with something like this:

def myfunction(x):
    labellist = []
    combolist = []
    layoutlist = []
    layout = QtGui.QVBoxLayout()
    for i in range(x):
        labellist.append(QtGui.QLabel('this is label'+str(i))
        combolist.append(QtGui.QComboBox())
        layoutlist.append(QtGui.QHBoxLayout())
        layoutlist[i].addWidget(labellist[i])
        layoutlist[i].addWidget(combolist[i])
        layout.addLayout(layoutlist[i])


self.connect(number,QtCore.SIGNAL("valueChanged(int)"),myfunction)

Even though it create ComboBoxes depending on the number user selected on spin box, when user increase the number (eg. 3 to 4), it doesn't remove the old 3comboBoxes, instead it become 7 comboboxes all together.

How do i fix this? Or Is there a better way to achieve the similar result?

Answer 1

You could delete and recreate all the comboboxes everytime your spinbox value changes. It may not be the most efficient, but it's quite simple.

Just have a list with references to the labels/comboxes as an attribute. In your slot, call deleteLater() on each item, then delete the reference by setting your list to []. Finally, recreate the items, add them to your layout and repopulate your list.

Also, you should have a look at New Style Signals and Slots. They are nicer than the ugly C++ style connect.

class DynamicComboBoxes(QtGui.QWidget):
    def __init__(self, parent=None):
        super(DynamicComboBoxes, self).__init__(parent)
        vbox = QtGui.QVBoxLayout(self)
        spinbox = QtGui.QSpinBox(self)
        spinbox.setRange(0,10)
        spinbox.valueChanged.connect(self.onChangeValue)
        vbox.addWidget(spinbox)
        self.grid = QtGui.QGridLayout()
        self.itemlist = []
        vbox.addLayout(self.grid)
        vbox.addStretch(1)


    def onChangeValue(self, val):
        for label, combobox in self.itemlist:
            label.deleteLater()
            combobox.deleteLater()
        self.itemlist = []
        for i in range(val):
            label = QtGui.QLabel('This is Label {}'.format(i))
            combobox = QtGui.QComboBox()
            self.grid.addWidget(label, i, 0)
            self.grid.addWidget(combobox, i, 1)
            self.itemlist.append([label, combobox])