Extending QML - Adding Types Example

The Adding Types Example shows how to add a new object type, Person, to QML. The Person type can be used from QML like this:

import examples.adding.people

Person {
    name: "Bob Jones"
    shoe_size: 12
}

Declare the Person Class

All QML types map to C++ types. Here we declare a basic C++ Person class with the two properties we want accessible on the QML type - name and shoeSize. Although in this example we use the same name for the C++ class as the QML type, the C++ class can be named differently, or appear in a namespace.

The Person class implementation is quite basic. The property accessors simply return members of the object instance.

from PySide6.QtCore import QObject, Property
from PySide6.QtQml import QmlElement

# To be used on the @QmlElement decorator
# (QML_IMPORT_MINOR_VERSION is optional)
QML_IMPORT_NAME = "People"
QML_IMPORT_MAJOR_VERSION = 1


@QmlElement
class Person(QObject):
    def __init__(self, parent=None):
        super().__init__(parent)
        self._name = ''
        self._shoe_size = 0

    @Property(str)
    def name(self):
        return self._name

    @name.setter
    def name(self, n):
        self._name = n

    @Property(int)
    def shoe_size(self):
        return self._shoe_size

    @shoe_size.setter
    def shoe_size(self, s):
        self._shoe_size = s

Running the Example

The main.py file in the example includes a simple shell application that loads and runs the QML snippet shown at the beginning of this page.

Download this example

main.py

# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause

"""PySide6 port of the qml/examples/qml/referenceexamples/adding example from Qt v6.x"""

from pathlib import Path
import sys

from PySide6.QtCore import QCoreApplication
from PySide6.QtQml import QQmlComponent, QQmlEngine

from person import Person


if __name__ == '__main__':
    app = QCoreApplication(sys.argv)

    engine = QQmlEngine()
    engine.addImportPath(Path(__file__).parent)
    component = QQmlComponent(engine)
    component.loadFromModule("People", "Main")

    person = component.create()
    if person:
        print(f"The person's name is {person.name}")
        print(f"They wear a {person.shoe_size} sized shoe")
    else:
        print(component.errors())
    del engine
    sys.exit(0)

person.py

# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause

from PySide6.QtCore import QObject, Property
from PySide6.QtQml import QmlElement

# To be used on the @QmlElement decorator
# (QML_IMPORT_MINOR_VERSION is optional)
QML_IMPORT_NAME = "People"
QML_IMPORT_MAJOR_VERSION = 1


@QmlElement
class Person(QObject):
    def __init__(self, parent=None):
        super().__init__(parent)
        self._name = ''
        self._shoe_size = 0

    @Property(str)
    def name(self):
        return self._name

    @name.setter
    def name(self, n):
        self._name = n

    @Property(int)
    def shoe_size(self):
        return self._shoe_size

    @shoe_size.setter
    def shoe_size(self, s):
        self._shoe_size = s

People/Main.qml

// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause

import People

Person {
    name: "Bob Jones"
    shoe_size: 12
}

People/qmldir

module People
typeinfo coercion.qmltypes
Main 1.0 Main.qml