QTreeView: hide parents but show children?

[ce_nort]

The project that I was needing this for ended up getting postponed indefinitely, so I stopped exploring the solution. It's been a long time since I was looking into this, but if the thread tells the tale correctly, then the concept of proxy models should help you: http://doc.qt.io/qt-5/qsortfilterproxymodel.html , http://doc.qt.io/qt-5/qabstractproxymodel.html . Wish I could be more helpful!

[WorstNoob]

Unfortunately so far it was of no particular use.
I do have a proxyfiltermodel in there, to filter the view and having the parents still displayed when any children matches is working just fine.
But I can't seem to get behind on how one could possibly make it ignore the parent items, but still display the children that are matching. If the parent is not accepted, then the children never get examined.

Thought about overriding mapTo/FromSource and somehow keeping a mapping but for some reason, even if there are no filters set for the proxyfiltermodel, it still doesn't map 1:1 to the source model, at least row of the proxy / source indexes don't match and I cannot see a pattern either. This unexpected behavior is throwing me off.
Plus would have to somehow delete that mapping when the source changes or generate it on the fly somewhere, which I don't know where yet.

[haiku]

I've been looking into how to do this and have found quite a nice way so long has your willing to use some private apis.

The issue is as WorstNoob states that there is no way to show only the children for a tree model using a QSortFilterProxyModel (that I could find), however you can use an internal Qt model called QQmlTreeModelToTableModel (QtQmlModels/private/qqmltreemodeltotablemodel_p_p.h) which as the name suggests proxies a tree model and converts it into a table model. Now you can proxy this table model and filter out parent rows as they are technically no longer parents. This is the model that Qts QML TreeView uses internally for what its worth but it should work whatever your usecase. It also preserves child parent relationships albeit in a different way so you still have that info available should you need it. One gotcha to look out for is that you need to manually expand the rows, otherwise it will only show the first row in the model.

[d_stranz]

Several years ago, the KDE project had a FlatProxyModel class. It doesn't seem to be a part of the current project, but you can still find it online as part of some other projects in the kptflatproxymodel.[h, cpp] files.

There is now a KDescendantsProxyModel in the KDE Frameworks (KItemModels section) which looks like it might be the replacement for the FlatProxyModel class.

These are both KDE "Tier 1" classes, meaning they have no dependence on other parts of KDE, only on Qt.

These do essentially the same thing as your private model does - flatten a tree into a table by turning each leaf into a row. Parents are added as new columns at the start of the row. It has the advantage that it isn't going to break your code in the future when it is modified. Private classes are private because the authors of Qt want to be able to change them while keeping the external public API the same.