设置从C++创建的qml对象的父对象不起作用

Question

我有一个创建QML对象的C++类，它需要五个参数：

//prototype 
// Q_INVOKABLE QQuickItem *createQmlObject(QObject *parent, QString path, QString id="", int x=0, int y=0);

QQuickItem * QmlItemCreator::createQmlObject(QObject* parent,QString path,QString id,int x,int y)
{
    QQmlEngine engine;
    QQmlComponent component(&engine, QUrl::fromLocalFile(path));
    QQuickItem * mainObject_;
    if(component.isError())
    {
        qWarning() << "QmlItemCreator::createQmlObject The QMLComponent for "
                   << path << " has errors: " << component.errorString();
    }
    else if (component.isReady())
    {
        mainObject_ = qobject_cast<QQuickItem*>(component.create());
        QQmlEngine::setObjectOwnership(mainObject_, QQmlEngine::JavaScriptOwnership);
        mainObject_->setProperty("id",id);
        mainObject_->setProperty("x",x);
        mainObject_->setProperty("y",y);
        mainObject_->setParent(parent);

       // qDebug()<<mainObject_<<"  "<<mainObject_->parent()<<"  "<<mainObject_->property("x");
    }
    else
    {
        componentComplete();
    }

    return mainObject_;
}

我在QML中使用它，如下所示：

 Item{
    id: idRoot
        Component.onCompleted:
       {
            var obj = qmlCreator.createQmlObject(idRoot,"path/test.qml")
           console.log(obj.parent)// print null !! 

       }
    }

在parent of the created object. However, when I print them from QML, theparenthas anulland the properties areundefined`.上下文中，我可以正确地打印我设置的属性值以及C++

我从C++和QML打印了创建对象的入口，我得到了相同的地址。我不明白是什么导致了这种行为。

谢谢你的帮助。

Answer 1

我通过在C++代码中添加以下代码行解决了这个问题：

mainObject_->setParentItem(qobject_cast<QQuickItem*>(parent));