QQmlApplicationEngine provides a convenient way to load an application from a single QML file. More

Inheritance diagram of PySide6.QtQml.QQmlApplicationEngine



Detailed Description

This class combines a QQmlEngine and QQmlComponent to provide a convenient way to load a single QML file. It also exposes some central application functionality to QML, which a C++/QML hybrid application would normally control from C++.

It can be used like so:

#include <QGuiApplication>
#include <QQmlApplicationEngine>

int main(int argc, char *argv[])
    QGuiApplication app(argc, argv);
    QQmlApplicationEngine engine("main.qml");
    return app.exec();

Unlike QQuickView , QQmlApplicationEngine does not automatically create a root window. If you are using visual items from Qt Quick, you will need to place them inside of a Window .

You can also use QCoreApplication with QQmlApplicationEngine , if you are not using any QML modules which require a QGuiApplication (such as QtQuick).

List of configuration changes from a default QQmlEngine :

  • Translations are reloaded when the QJSEngine::uiLanguage / Qt.uiLanguage property is changed.

  • Automatically sets an incubation controller if the scene contains a QQuickWindow .

  • Automatically sets a QQmlFileSelector as the url interceptor, applying file selectors to all QML files and assets.

The engine behavior can be further tweaked by using the inherited methods from QQmlEngine .

class PySide6.QtQml.QQmlApplicationEngine([parent=None])

PySide6.QtQml.QQmlApplicationEngine(filePath[, parent=None])

PySide6.QtQml.QQmlApplicationEngine(url[, parent=None])


Create a new QQmlApplicationEngine with the given parent. You will have to call load() later in order to load a QML file.


filePath – str



PySide6.QtQml.QQmlApplicationEngine.loadData(data[, url=QUrl()])

Loads the QML given in data. The object tree defined by data is instantiated immediately.

If a url is specified it is used as the base url of the component. This affects relative paths within the data and error messages.

If an error occurs, error messages are printed with qWarning .

PySide6.QtQml.QQmlApplicationEngine.objectCreated(object, url)
Return type

Returns a list of all the root objects instantiated by the QQmlApplicationEngine . This will only contain objects loaded via load() or a convenience constructor.


In Qt versions prior to 5.9, this function is marked as non-const.


extraFileSelectors – list of strings

Sets the extraFileSelectors to be passed to the internal QQmlFileSelector used for resolving URLs to local files. The extraFileSelectors are applied when the first QML file is loaded. Setting them afterwards has no effect.

See also

QQmlFileSelector setExtraSelectors



Sets the initialProperties with which the QML component gets initialized after it gets loaded.

QQmlApplicationEngine engine;

EventDatabase eventDatabase;
EventMonitor eventMonitor;

    { "eventDatabase", QVariant::fromValue(&eventDatabase) },
    { "eventMonitor", QVariant::fromValue(&eventMonitor) }