- Qt Creator Manual
- Managing C++ Backend Objects
- Qt Creator Manual 4.15.0

Adding Bindings Between Properties ◦ Adding States

# Managing C++ Backend Objects

Many applications provide QObject objects implemented in C++ that work as a bridge between QML and C++. Such objects are typically registered with `qmlRegisterType` or `qmlRegisterSingletonType` and then used by QML to communicate with the C++ backend. Another example of such objects are the state machines created by the Qt SCXML Compiler.

Backend objects in a QML file are accessible if the QML file contains the required imports. In addition, for a non-singleton QObject, a dynamic property that contains the QObject must be specified.

A local QObject is instantiated in the current .qml file, as follows:

     property MyType myType: MyType {}.

Otherwise the property is just defined, as follows:

     property MyType myType

To manage backend objects:

1. Select Connection View > Backends to view accessible backend objects.

2. Select the (Add) button to add a backend object in the Add New C++ Backend dialog.

3. In the Type field, select the backend QObject to add.
4. Select the Define object locally check box if the QObject is not registered as a singleton.
5. Select OK to add the required import and to create the property for a non-singleton object.

Adding Bindings Between Properties ◦ Adding States