Using QFileSystemModel, QTreeView, and QSortFilterProxyModel

Zbigniew-Sch

Hi,

I'm using QFileSystemModel, QTreeView, and QSortFilterProxyModel.
Here's the problem: when I rename a directory and delete a file from that directory, the file is deleted,
but the corresponding item in QTreeView isn't.
If I only use QFileSystemModel and QTreeView without QSortFilterProxyModel, everything works correctly.
Has anyone else encountered this problem, or does anyone have a solution?

Zbigniew-Sch

QLZTreeView - see above
Header:

class QLZTreeView : public QTreeView
{
	Q_OBJECT

public:

	explicit QLZTreeView(QWidget* parent = nullptr);
	~QLZTreeView();

protected:
	void renameCurrentObject(QModelIndex coCurrentIndex);
	void deleteCurrentObject(QModelIndex coCurrentIndex);
	void closeEditor(QWidget* editor, QAbstractItemDelegate::EndEditHint hint) override;

private slots:
	void customContextMenu(const QPoint& point);
};

QSortFilterProxyModel - is standard Qt class

QLZFileSystemModel - see above
Header:

  class QLZFileSystemModel : public QFileSystemModel
 {
 Q_OBJECT

 public:
 explicit QLZFileSystemModel(QObject* parent = nullptr);
 ~QLZFileSystemModel();

 protected:
 Qt::ItemFlags flags(const QModelIndex& index) const override;

};

main.cpp - and that's all.

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    LZImageViewerTest window;
    window.show();
    return app.exec();
}

sierdzio

There are a few ways to fix this, but the easiest is to enable dynamicSortFilter

Zbigniew-Sch

Hi,

I called "mySortFilterProxyModel->setDynamicSortFilter(false)" but unfortunately the file item is not deleted from the QTreeView.

sierdzio

I meant you need to set it to true, but judging from your reply it was already set so (it is the default setting after all).

Another way to force this functionality is to call QSortFilterProxyModel::invalidate() whenever your base model changes, you can do this by connecting some signals and slots if I recall correctly.

Zbigniew-Sch

I set it to "true" (but that's the default) and called "invalidate()", but it still doesn't work.

sierdzio

Hm, no ideas then. Might as well be a bug of some sorts, although it seems quite unlikely in such an old and well tested class. This is on some desktop platform, with an up-to-date Qt version?

sierdzio

I think on some old project in a vaguely similar situation, toggling recursiveFilteringEnabled did help me, but I may be misremembering things.

Zbigniew-Sch

I'm using Windows 11 and Qt 6.10. I think this is a bug, or does anyone have a solution?
I've tried various changes, but it doesn't work.

jeremy_k

It would help to have a minimal working example program to look at. This functions for me as I expect with Qt 6.9 on macOS:

#include <QApplication>
#include <QFileSystemModel>
#include <QSortFilterProxyModel>
#include <QTreeView>

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

    QFileSystemModel model;
    model.setRootPath("/tmp");

    QSortFilterProxyModel proxyModel;
    proxyModel.setSourceModel(&model);

    QTreeView view;
    view.setModel(&proxyModel);
    view.show();

    return a.exec();
}

Zbigniew-Sch

Sorry, but you didn't read the question. It's about the following: renaming a directory and
deleting a file from that directory, but the file item isn't being deleted from QTreeView.

JonB

@Zbigniew-Sch
You still need to provide a minimal example of code you use which shows this behaviour:

We need to see exactly what your code is.
If someone wants to test behaviour why should they have to write code from scratch? (I did read your question yesterday, but no code => I'm not going to try anything.)

So... can you confirm that if you try precisely the code in @jeremy_k's code the problem arises for you? Assuming so, then: as I understand it, you are performing a directory rename and then a delete file within the renamed directory, both of these actions from the QTreeView? (You are not doing these file operations externally to your program on the file system, are you?) So someone else needs to do that while running the same code as you. I don't know whether the QTreeView bound to a file system offers you "rename" and "delete" automatically, but if not then we need you add whatever minimal for that to the code for people to try.

jeremy_k

@Zbigniew-Sch said in Using QFileSystemModel, QTreeView, and QSortFilterProxyModel:

Sorry, but you didn't read the question. It's about the following: renaming a directory and
deleting a file from that directory, but the file item isn't being deleted from QTreeView.

Yes, I did read the question. The MWE I posted behaves as I expect, given an out-of-process directory renaming and file deletion.

There may be a bug. Without a program to examine, it's unclear whether it is likely to lie in the OS, library, application code, or understanding of how each behaves.

JonB

@jeremy_k said in Using QFileSystemModel, QTreeView, and QSortFilterProxyModel:

given an out-of-process directory renaming and file deletion

Oh, I had thought it more likely OP was doing in-process operations via code on the QTreeView! Shows how simple details matter :)

jeremy_k

@JonB said in Using QFileSystemModel, QTreeView, and QSortFilterProxyModel:

@jeremy_k said in Using QFileSystemModel, QTreeView, and QSortFilterProxyModel:

given an out-of-process directory renaming and file deletion

Oh, I had thought it more likely OP was doing in-process operations via code on the QTreeView! Shows how simple details matter :)

+1 on details mattering. I didn't see a point in guessing and complicating the code for an example of a MWE.

JonB

@jeremy_k
OP is Windows, you are MacOS. I am Linux but not tested. May have to await a Windows user. If it's out-of-process it relies on the QFileSystemWatcher and the OS behaviour for notifications, that might or might not be relevant. If it's that area OP could debug-out to confirm the QFSW signals being emitted.

If it's a fault in higher-level Qt logic instead we should be able to reproduce, but OP may have to confirm exactly what he does in outside world.

And if it is an issue only when there is a QSortFilterProxyModel we need to know whether OP has set any sorting or filtering on it.

jeremy_k

@JonB said in Using QFileSystemModel, QTreeView, and QSortFilterProxyModel:

If it's out-of-process it relies on the QFileSystemWatcher and the OS behaviour for notifications, that might or might not be relevant.

This seems unlikely to be relevant. The original post says that connecting the file system model directly to the view does what is expected. I don't expect to find any file or operating system specific code in the proxy model.

Zbigniew-Sch

I wrote a small program and I'm having the same problem.
This is definitely a bug in Qt, without QSortFilterProxyModel, everything works correctly.
I renamed the directory in my program and deleted a file from that directory
using Windows Explorer – it works correctly now. I'm out of ideas.

jeremy_k

The general advice from this thread remains valid:

The existence of a test program doesn't help confirm or deny if nobody else can see the program.
Bug reports can be filed at https://bugreports.qt.io/. Chances are high that whoever responds will also ask for a demonstrator.

Christian Ehrlicher

@jeremy_k said in Using QFileSystemModel, QTreeView, and QSortFilterProxyModel:

Chances are high that whoever responds will also ask for a demonstrator.

Higher than high - otherwise it will be closed sooner or later with 'Needs more information'

Zbigniew-Sch

How can I upload an entire example project as a ZIP file?