CODEWITHSUNDEEP
pythonpyqtqmlpyqt5
Julien Séveno-Piltant
Julien Séveno-Piltant

Reputation: 370

findChild returns None

I saw other people asking this question but none of what I tried worked. I am using PyQt 5.10.1.

Here is python code:

app = QGuiApplication(sys.argv)
view = QQuickView()
view.setSource(QUrl("module/Layout.qml"))
print(view.rootContext())
print(view.findChild(QObject, 'launcherComponent'))
import pdb; pdb.set_trace()
sys.exit(app.exec())

And here is the QML code:

import QtQuick 2.7
import QtQuick.Controls 2.0
import QtQuick.Window 2.2

import "calendar/resources" as CalendarComponent
import "weather/resources"  as WeatherComponent
import "launcher/resources" as LauncherComponent

import Test 1.0
import Weather 1.0
import Calendar 1.0
import Launcher 1.0


ApplicationWindow {
    id: appId
    width: Screen.desktopAvailableWidth
    height: Screen.desktopAvailableHeight
    visible: true
    modality: Qt.ApplicationModal
    flags: Qt.Dialog
    title: qsTr("NarcisseOS")
    color: "black"

    LauncherComponent.LauncherComponent {
        id: launcherComponentId
        objectName: launcherComponent
        height: parent.height
        width: parent.width
        anchors.centerIn: parent
    }
}

I tried everything I thought about. But this findChild function is only returning None.

I tried to reinstall PyQt5. And I tried to put the objectName property in a Rectangle object, I thought maybe a more generic one would be working. None of it worked.

Upvotes: 3

Views: 3977

Answers (1)

eyllanesc
eyllanesc

Reputation: 243897

Your code has several errors:

  • The objectName property must be a string:
LauncherComponent.LauncherComponent {
    id: launcherComponentId
    objectName: "launcherComponent"
    height: parent.height
    width: parent.width
    anchors.centerIn: parent
}
  • Another error is that if you are going to use ApplicationWindow you should not use QQuickView since ApplicationWindow creates a toplevel and QQuickView as well so you will have 2 toplevels and you are looking for the son of QQuickView but not in the ApplicationWindow children, so I recommend you modify your .py to:
import sys

from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtQml import *

app = QGuiApplication(sys.argv)
engine = QQmlApplicationEngine()
engine.load(QUrl("module/Layout.qml"))
if len(engine.rootObjects()) == 0:
    sys.exit(-1)
print(engine.rootObjects()[0].findChild(QObject, 'launcherComponent'))
sys.exit(app.exec_())

That is, you must use QQmlApplicationEngine.

Upvotes: 2

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