I was able to fix this with the following: https://github.com/qt/qtbase/commit/7d92ef63d7c And the following patch in Qt-5.15.2 which tremendously improved the timing: [image: 33f58cff-aeb8-48d6-ac64-d8120b77d822.png]

@VRonin Awesome thanks! I was able tho to just grab the 2 files and use them directly so yay! This tree model is epic. It does 90% of what I wanted ! Now I just gotta figure out how to hide parent/groups, so I only see items, but that should be fine, super awesome, thanks! Edit1. using sort filter model later to decide if I want to show parents/etc worked just fine, yay!

Hi, Are your properly calling the "signaling" methods in your custom model when you modify it ?

Hi, Your proxy has a member variable that you set as source model. This looks wrong as already suggested in your other thread.

That's correct. What you are trying to do with only one model is like having two pilots in one car trying to drive into two different directions at the same time.

@VRonin yea, ty, already fix it

@gde23 said in QTreeView with QSortFilterProxyModel extremly slow with many (~5000) items: Thanks for demanding a minimal example :) Thx for trying to create one - sadly a lot of people don't understand the demand for this but this here is a good example why it's needed :)

@VRonin wow, it's really work. Thank you

@JKSH Yep I'm having a full run through the app now to ensure everything happens in GUI thread - that is widget/affects widget.

@jeremy_k Wow, Awesome ! Thanks for your answer and massive props to @VRonin !

So this needs a bump now, I tried using setRootIndex but that did not work... https://forum.qt.io/topic/102454/qtreeview-setrootindex-changing-header-incorrect-columncount/6 So I'm back to proxyModels... my main issue now is, how can I set a new rootIndex/item to that sortFilterProxy kick in from right infex and not from old index? As far as I can tell the filtering starts when tree request item, which usually is the root item, so header item. Since thats not the item I want to show I return false & since I return false there are no more items to query - thus no children thus the item that I actually want to show as new root never gets called/checked... if I use filterAcceptsRow() function... so where/who do I change to set different rootItem via proxy model?

You may also try to set dynamicSortFilter: true, but only if you do not modify contents of model through proxy model. invalidate() calls are expensive and you should only do it when you know what you are doing. If you modify contents of your model through proxy model and/or you need to filter and sort on demand, invalidateFilter() and sort() is what you are looking for.

@VRonin said in Implement QSortFilterProxyModel with own TreeModel?: Good guess, can you show us your code? I solved it: I had to pass the parent index (tree structure), so the line should look like this: QVariant data = m_proxy->data(m_proxy->index(index.row(), 4, index.parent()));

Ok I found what was causing this awful bug. When I check if the map contains the index, I actually check the raw index not the QPersistantModelIndex so this is not the same object and I think qmap does not check equality using == operator . So I have to iterate over the map and check using QPersistantModelIndex "==" operators which can compare from a QModelIndex.

@VRonin Thank you. Yesterday, I tried same things. But it was not working than later on I found, I forget to add file name in SOURCE , HEADER. Now it is work as expectation.

Thank you @mrjj and @Christian for answer. I am able to make user Checkable. class CustomListModel : public QStandardItemModel { public: Qt::ItemFlags CustomListModel::flags(const QModelIndex & index) const { Qt::ItemFlags defaultFlags = QStandardItemModel::flags(index); if (index.isValid()) { return defaultFlags | Qt::ItemIsUserCheckable; } return defaultFlags; } CustomListModel(const int row, const int coloumn) : QStandardItemModel(row, coloumn) { } }; and modification. hwListProxyModel->setSourceModel(new CustomListModel (0, 0));

@IMAN4K said in change QSortFilterProxyModel behaviour for multiple column filtering: Answer from stackfverflow : http://stackoverflow.com/questions/39488901/change-qsortfilterproxymodel-behaviour-for-multiple-column-filtering This answer is the typical example that lead people to say subclassing QSortFilterProxyModel, which would likely have a very limited reusability It's bad. the proxy model implementation should not depend on the structure of the underlying data in sourceModel