Unable to send signal from Button created in Python loop

Question

I am trying to create a series of buttons in a loop. Each button gets an id number as it's text and when the button is clicked it is supposed to send the id number to a function that will open an archived order. At this time I just want to print the order number to prove that the signal works and each button is connected to the correct order number.

ui.cmdOpen = QtWidgets.QPushButton(ui.frOrdHist)
ui.cmdOpen.setGeometry(QtCore.QRect(269, line1Y, 61, 22))
ui.cmdOpen.setText(iOrderId)
ui.cmdOpen.setObjectName("cmdOpen")
ui.cmdOpen.clicked.connect(lambda button=ui.cmdOpen:displayOrder(ui, button))


def displayOrder(ui, button):
    i = button.text()
    print(i)

When I click the button, I get an error message that says "boolean object has no text attribute"

I tried passing the order number directly and it would print "False" so still a boolean. I don't know where the boolean is coming from, it must be something wrong in the signal.

If you're creating buttons in a loop, you may be running into a problem with closures. It will be easier to diagnose if you include the loop code — theodox
– theodox, Commented Oct 28, 2016 at 17:17

ekhumoro · Accepted Answer · 2021-02-25 13:27:20Z

3

The clicked signal always sends the checked state of the button. So this will overwrite your default button argument with a boolean value, which is why you get the AttributeError (i.e. because bool doesn't have that method). You should instead make the connection like this:

ui.cmdOpen.clicked.connect(
    lambda checked, button=ui.cmdOpen: displayOrder(ui, button))

PS: another common source of this issue is the triggered signal of QAction. If you ever find your slots receiving unexpected inputs, it's always worth checking the Qt Docs to see if the signature of the signal has any parameters with default values - i.e. that look something like this:

void QSomeClass::someSignal(bool param = false)

edited Feb 25, 2021 at 13:27

answered Oct 28, 2016 at 18:06

ekhumoro

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