Exposing QModelIndex in C++ to QML VisualDataModel

[hurmatt]

I'm trying to implement a very basic file browser that only shows files in a set directory. Using the QFileSystemModel, I've set the root path but the connected QML VisualDataModel still shows the entire path. I have to keep clicking to get the directory I want ("/testfolder/test"). I tried using the Symbian FolderModel QML element but it's a bit buggy, it doesn't refresh properly when a file is added or deleted.

I tried exporting the index of the root path to the VisualDataModel using a QModelIndex but I keep getting the following compile errors:

../../QtSDK/Simulator/Qt/gcc/include/QtCore/qvariant.h:433: error: 'QVariant::QVariant(void*)' is private
../qfiledemo/main.cpp:46: error: within this context

I want to use the QModelIndex to set the VisualDataModel to jump directly to the path I want, rather than starting out at the top of the filesystem. Any way to expose a QVariant to QML without making a custom class? Thanks!

Here is my main.cpp:

int main(int argc, char *argv[])
{
  QApplication app(argc, argv);
 
  QDeclarativeView view;
 
  QFileSystemModel model;
  model.setRootPath(QString("/testfolder/test"));    
  QModelIndex rootidx = model.index("/testfolder/test"); // find the correct index to pass to VisualDataModel
 
  view.rootContext()->setContextProperty("dirModel", &model);
  view.rootContext()->setContextProperty("rootIndex", &rootidx); // this always fails!
  view.setSource(QUrl::fromLocalFile("qml/qfiledemo/main.qml"));
  view.show();
 
  return app.exec();
}

int main(int argc, char *argv[])
{
  QApplication app(argc, argv);

  QDeclarativeView view;

  QFileSystemModel model;
  model.setRootPath(QString("/testfolder/test"));    
  QModelIndex rootidx = model.index("/testfolder/test"); // find the correct index to pass to VisualDataModel

  view.rootContext()->setContextProperty("dirModel", &model);
  view.rootContext()->setContextProperty("rootIndex", &rootidx); // this always fails!
  view.setSource(QUrl::fromLocalFile("qml/qfiledemo/main.qml"));
  view.show();

  return app.exec();
}

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My main.qml:

ListView {
    id: view
    width: 300
    height: 400
 
    model: VisualDataModel {
        model: dirModel
 
        delegate: Rectangle {
            width: 200; height: 25
            Text { text: filePath }
 
            MouseArea {
                anchors.fill: parent
                onClicked: {
                    if (model.hasModelChildren) {
                        view.model.rootIndex = view.model.modelIndex(index)
        // Would be great if I could set the rootIndex in here to jump straight to the directory I want
 
                    }
                }
            }
        }
    }
}

ListView {
    id: view
    width: 300
    height: 400

    model: VisualDataModel {
        model: dirModel

        delegate: Rectangle {
            width: 200; height: 25
            Text { text: filePath }

            MouseArea {
                anchors.fill: parent
                onClicked: {
                    if (model.hasModelChildren) {
                        view.model.rootIndex = view.model.modelIndex(index)
        // Would be great if I could set the rootIndex in here to jump straight to the directory I want

                    }
                }
            }
        }
    }
}

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[Le_B]

I didn't test it but maybe you can subclass QFileSystemModel and add someting like Q_INVOKABLE QModelIndex root_index(const QString& path) const;
and in qml do: view.model.rootIndex = dirmodel.root_index("/testfolder/test"); in a Component.onCompleted event

[hurmatt]

I found something similar at http://qt-project.org/forums/viewthread/3306 where the poster used a custom subclass from QFileSystemModel and managed to get QModelIndex exposed to QML.

I can't make heads or tails of the solution since my C++ is really rusty and I haven't used subclasses from Qt classes before Any documentation on doing this with Qt?