QSortFilterProxyModel drag/drop issue...

Dariusz

Hey

So I'm trying to use the QSortFilterProxyModel system to do some filtering for matching text in my model. Other than that I want to be able to perform drag/drop when view is unfiltered. Now I'm using my own base model derived from QAbstractItemModel and I've re-created the mime/dropMime/canDropMime data functions (not insert/append/in/etc/etc in either of classes) - in my base model - not proxy. But when ever I drop stuff in the proxyView I get incorrect results... There seem to be some kind rule to it.. if I drag/drop on root I get weird stuff, but if I drag/drop within valid parent, it seem to work ?

I also get random qsortfilterproxymodel.cpp line 548 errors... Index from wrong model pased to map to source thini... this appear to happen when I try to re-select dropped items in my treeView, as I have a list of items, and I did index() on them and passes it to itemSelectionRange... I guess index() is wrong index as it comes from base model and not proxy model, so I think I can fix that.

Can any1 help out?

TIA

SGaist

Hi,

You should share your model implementation. It will help people check for your issues.

Dariusz

The base model or the proxy one ?

The base model has

    QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const override;
    QModelIndex parent(const QModelIndex &child) const override;
    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
    int columnCount(const QModelIndex &parent = QModelIndex()) const override;
    bool hasChildren(const QModelIndex &parent = QModelIndex()) const override;
    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
    bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole);
    QMimeData *mimeData(const QModelIndexList &indexes) const;
    bool canDropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent) const;
    bool dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent);
    Qt::ItemFlags flags(const QModelIndex &index) const;
    GenericTreeNode *getItemFromIndex(const QModelIndex &index) const;
    QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const;
    Qt::DropActions supportedDropActions() const;
    Qt::DropActions supportedDragActions() const;
    QModelIndex getIndexFromItem(GenericTreeNode *item);

Reimplemented... Most of the functions are mostly thesame or almost thesame as qt implementation here. With exception that I always force to column 0 when drag/drop....

the Proxy only :

bool filterAcceptsRow(int source_row, const QModelIndex &source_parent) const;

for now.

Regards
Dariusz

SGaist

Since you re-implemented the two models, then both.

Dariusz

Hey

So I was just typing over the classes/functions in comment and testing as I go and I think I might have fixed it... it ened up being beginRemoveRows and begineInsertRows calls. It seems that I mostly ignored them in my standalone model implementation due to issues they were generating... but now that I fixed the indexing they appear to work properly... sooo.. yay? Still testing, might be back in a min :- )

Dariusz

Okay... it seems to work and I needed to fix my beginInsert/beginRemove rows...

Ok so maybe 1 side question... not to start another proxy topic...

Say I have a data set with categories, each having a list of sub categories... say if I just want to display 1 category + all its sub categories, should I implement it via QSortFilterProxyModel ?

The only way that currently I can think off is to check each row parent, untill I reach the 1st child of root parent and see if that child is visible... seems like a lot of recursive parent checking for it to work tho...

I kinda wish I could just setProxyImagineryRootItem(sourceModel()->rootItem()->child[0]) or something like that so that the view only displays data of that child?

JonB

@Dariusz
I believe you are saying: you have a number of top-level items, but you only wish to display one of them, downward. I recall this being asked a few weeks ago (in the context of a QFileSystemModel), and the answer was to use a QSortFilterProxyModel to filter away all the top-level items except for the one you wish to display. That is assuming you cannot just get away with QAbstractItemView::setRootIndex(). I may be misunderstanding your question.

Dariusz

@JonB said in QSortFilterProxyModel drag/drop issue...:

@Dariusz
I believe you are saying: you have a number of top-level items, but you only wish to display one of them, downward. I recall this being asked a few weeks ago (in the context of a QFileSystemModel), and the answer was to use a QSortFilterProxyModel to filter away all the top-level items except for the one you wish to display. That is assuming you cannot just get away with QAbstractItemView::setRootIndex(). I may be misunderstanding your question.

That sounds exactly what I want I think!

I have

    root
        >> Category1
            >> child1
            >> child2
            >> child3
            >> subCategory1
            >> subCategory2
            >> etc etc
        >> Category2
        >> Category3
        >> Category4

And I'd like to only display Category1 + its children or 2/3/4 or subCategory1/2 etc etc...

I will try the setRootIndex! Sounds like its what I want to do here. However its in treeView... humh... I was hoping I can set it on all views displaying certain proxy model.... will try it out 1st.

Thanks!

JonB

@Dariusz
You're on your own because I don't really know what I'm talking about :) But for

I was hoping I can set it on all views displaying certain proxy model

I think that's is indeed where you would stick to my

use a QSortFilterProxyModel to filter away all the top-level items except for the one you wish to display

Dariusz

@JonB said in QSortFilterProxyModel drag/drop issue...:

@Dariusz
You're on your own because I don't really know what I'm talking about :) But for

I was hoping I can set it on all views displaying certain proxy model

I think that's is indeed where you would stick to my

use a QSortFilterProxyModel to filter away all the top-level items except for the one you wish to display

Hmmm I was trying the setRootIndex but so far no luck... probably due to my subclassing of model...

How can I filter it in QSortModelTho ? The filterAcceptsRow() only give me 1 item at a time, and if a item is child of a child of a child of a category that I want, then I have to filter them all recursively untill I get category parent and then check if its the one I wish to see... Feels like a lot of work for filtering that will get slow with large data sets... I guess the question is, how can I filter an item and show all its children?

Edit, for now I've done it with while loop...but its not too "Pretty" sadly...

JonB

@Dariusz
This: https://forum.qt.io/topic/100194/how-to-show-root-directory-in-qfilesystemmodel/8
was the post I had vaguely recalled. It was indeed QFileSystemModel. The OP concluded with

i will have to use QSortFilterProxyModel then..

Have a read, I don't know whether it relates to your situation.