Jump to content
Ultimaker Community of 3D Printing Experts

Basic trouble with Qt slot


Recommended Posts

Posted (edited) · Basic trouble with Qt slot

I'm trying to develop a Cura extension, while, at the same time, figuring out Qt.  Unfortunately, I'm struggling with something that seems like it should be very basic and can't figure out where I'm going wrong.


Essentially, I want to display a dialog and call a Python function when the dialog is accepted. 


My understanding is that, by decorating a function with the @pyqtSlot decorator, it should be callable from my QML.  However, attempting to do this results in a complaint that my decorated Python function "is not a function".  What I'm doing seems to match what I've seen in other plugins and online, but it's just not working.


Here's the Python code that's not working:


import os.path
from PyQt5.QtCore import QObject, pyqtSlot

from UM.Application import Application
from UM.Extension import Extension
from UM.Logger import Logger
from UM.PluginRegistry import PluginRegistry

class TempTower(Extension):
    def __init__(self):

        # Add menu items for this plugin
        self.addMenuItem("Generate a Temp Tower", self._showTempTowerDialog)

        # The dialog is generated the first time it's needed
        self._settingsDialog = None

    ##  Creates a modal dialogue with information about the selection.
    def _createDialogue(self, filename):
        qml_file_path = os.path.join(PluginRegistry.getInstance().getPluginPath(self.getPluginId()), filename)
        component = Application.getInstance().createQmlComponent(qml_file_path, {"manager": self})
        return component

    def _showTempTowerDialog(self):
        if self._settingsDialog is None:
            self._settingsDialog = self._createDialogue("test.qml")
        Logger.log('d', 'Dialog dismissed')

    def tempTowerDialogAccepted(self):
        Logger.log('d', 'Dialog was accepted')


And the corresponding QML file:

import QtQuick 2.3
import QtQuick.Controls 1.2
import QtQuick.Layouts 1.1

import UM 1.1 as UM

    id: dialog

    rightButtons: Button
        text: "Generate"


When I click the "Generate" button in the QML dialog, Cura displays the following error (snipped somewhat for clarity):

file:/TempTower/test.qml:23: TypeError: Property 'tempTowerDialogAccepted' of object QVariant(PyQt_PyObject, ) is not a function


Can anyone give me a hint as to what I'm doing wrong here?  It's embarrassing, but I simply cannot figure this out.

Edited by bradk3
Added a bit more explanation.
  • Link to post
    Share on other sites

    Posted · Basic trouble with Qt slot

    *Sigh*  Never mind.  It looks like my problem was not inheriting from QObject.  I Changed the class definition to this:


    class TempTower(QObject, Extension):


    And it seems to work now.

    • Like 1
    Link to post
    Share on other sites

    Create an account or sign in to comment

    You need to be a member in order to leave a comment

    Create an account

    Sign up for a new account in our community. It's easy!

    Register a new account

    Sign in

    Already have an account? Sign in here.

    Sign In Now

    • Our picks

      • New here? Get ahead with a free onboarding course
        Often getting started is the most difficult part of any process. A good start sets you up for success and saves you time and energy that could be spent elsewhere. That is why we have a onboarding course ready for
        Ultimaker S5 Pro Bundle, Ultimaker S5, Ultimaker S3 Ultimaker 2+ Connect.   
        They're ready for you on the Ultimaker Academy platform. All you need to do to gain access is to register your product to gain free access. 
        Ready? Register your product here in just 60 seconds.
          • Like
        • 11 replies
    • Create New...