Qt Filesystembrowser: How to change root directory and update view - c++

Question

I am trying to extend the qt filesystembrowser example (Qt-Creator -> Welcome -> Examples -> filesystembrowser). I added a button to main.qml
Button {
id: button
x: 28
y: 12
text: qsTr("rootPath")
onClicked: {
view.model.setRoot("/home/myusername/test/")
view.update()
}
}
which should change the root directory. For this, I also added the following function
Q_INVOKABLE QModelIndex setRoot(QString newPath) {
qInfo() <<"root path "<< this->rootPath();
newPath.replace(0,7,"");
setRootPath(newPath);
}
After hitting the button twice, qInfo tells me that the root path is now /home/myusername/test/ but the view is not updated. What am I missing here?

Answer 1

The problem is that the rootIndex of the TreeView does not change because it does not update the view.
One solution is to create a rootIndex property that returns the index that is placed in the TreeView, this must be changed when a new path is established, for it is going to overwrite the setRootPath method and eliminate the rootPathIndex property that was sent through setContextProperty():
main.cpp
...
class DisplayFileSystemModel : public QFileSystemModel {
Q_OBJECT
Q_PROPERTY(QModelIndex rootIndex READ rootIndex WRITE setRootIndex NOTIFY rootIndexChanged)
public:
...
Q_INVOKABLE QModelIndex setRootPath(const QString &newPath){
QModelIndex ix = QFileSystemModel::setRootPath(newPath);
setRootIndex(ix);
return ix;
}
QModelIndex rootIndex() const{
return mRootIndex;
}
void setRootIndex(const QModelIndex &rootIndex){
if(mRootIndex == rootIndex)
return;
mRootIndex = rootIndex;
Q_EMIT rootIndexChanged();
}
Q_SIGNAL void rootIndexChanged();
private:
QModelIndex mRootIndex;
};
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QQmlApplicationEngine engine;
qmlRegisterUncreatableType<DisplayFileSystemModel>("io.qt.examples.quick.controls.filesystembrowser", 1, 0,
"FileSystemModel", "Cannot create a FileSystemModel instance.");
DisplayFileSystemModel *fsm = new DisplayFileSystemModel(&engine); // change
fsm->setRootPath(QDir::homePath());
fsm->setResolveSymlinks(true);
engine.rootContext()->setContextProperty("fileSystemModel", fsm);
engine.load(QUrl(QStringLiteral("qrc:///main.qml")));
if (engine.rootObjects().isEmpty())
return -1;
return app.exec();
}
#include "main.moc"
main.qml
...
Row {
...
Repeater {
model: [ "rootPath", "None", "Single", "Extended", "Multi", "Contig."]
Button {
text: modelData
exclusiveGroup: eg
checkable: modelData != "rootPath"
checked: index === 1
onClicked: {
if(modelData != "rootPath")
view.selectionMode = index
else{
view.model.setRootPath("/home/myusername/test/")
}
}
}
}
}
...
TreeView {
id: view
anchors.fill: parent
anchors.margins: 2 * 12 + row.height
model: fileSystemModel
rootIndex: fileSystemModel.rootIndex //change
selection: sel
...
The complete example can be found in the following link.