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

Inheritance diagram of PySide2.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 :

  • Connecting Qt. quit() to quit()

  • Automatically loads translation files from an i18n directory adjacent to the main QML file.

  • 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 QQmlApplicationEngine([parent=None])

QQmlApplicationEngine(filePath[, parent=None])

QQmlApplicationEngine(url[, parent=None])

param parent


param url


param filePath


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




filePath – unicode

PySide2.QtQml.QQmlApplicationEngine.loadData(data[, url=QUrl()])
  • dataQByteArray

  • urlQUrl

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 .

PySide2.QtQml.QQmlApplicationEngine.objectCreated(object, url)
  • objectQObject

  • urlQUrl

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 .