How to use QStandardItemModel + QStandardItem sort two types data independent

[Aizzzz]

Hi，I'm trying to write my own TreeWidget for inherite QStandardItemModel, and it will show data just list file and folder. I want to sort folder and file independently, just like:

raw data: 
@root
|-- D file
|-- C folder
|-- B folder
`-- A file

after sort, i want to it look like

raw data: 
@root
|-- A file
|-- D file
|-- B folder
`-- C folder

I try to write my own sort function refer to QTreeWidget::sortItems, but it not works when i call it

class MyOwnTreeModel : public QStandardItemModel
{    
    void sortChilds(QStandardItem*pItems, Qt::SortOrder order);
}

void MyOwnTreeModel::sortChilds(QStandardItem*pItem, Qt::SortOrder order)
{
    QVector<QPair<QStandardItem*, int> > sorting;

    for (int i = 0; i < pItem->rowCount(); i++)
    {
        /* get one type item, eg. all file or all folder */
    }

/*  do sorting*/

    QModelIndexList mFrom, mTo;
    for (int r = 0; r < sorting.count(); ++r)
    {
        int oldRow = sorting.at(r).second;
        if (oldRow == r)
            continue;
        QModelIndex from = createIndex(sorting[r].second, 0, sorting.at(r).first);

     /* it seems setChild not work */
        pItem->setChild(sorting[r].second, 0, sorting.at(r).first);

        if (persistentIndexList().contains(from))
        {
            QModelIndex to = createIndex(r, 0, sorting[r].first);
            mFrom.append(from);
            mTo.append(to);
        }
    }
    if (!mFrom.empty())
        changePersistentIndexList(mFrom, mTo);

}

when i call sortChilds in my own tree widget, just like ownModel->sortChilds(item), there is nothing happened. mTo and From shows the right order, it seems QStandardItem::setChild not work but i don't know why.

[VRonin]

is A file 2 columns or 1?

[Aizzzz]

Just 1 column, file and folder just let's know there are two types, and identified by userRole

[VRonin]

EDIT: wrong code, see below

void MyOwnTreeModel::sortChilds(QStandardItem*pItem, Qt::SortOrder order)
{
if(!pItem) return;
const int oldSortRole = sortRole();
setSortRole(Qt::UserRole);
pItem->sortChildren(0,order);
setSortRole(Qt::DisplayRole);
pItem->sortChildren(0,order);
setSortRole(oldSortRole);
}

[JonB]

@VRonin
Hmm. Cheaty!

Does your code sort by UserRole and then by DisplayRole, is that why you write what you have? If so where does docs say that will work??

[VRonin]

@JonB said in How to use QStandardItemModel + QStandardItem sort two types data independent:

Cheaty!

Indeed. The correct way would be to subclass QStandardItem and reimplement operator< but "aint nobody got time for that"

[JonB]

@VRonin said in How to use QStandardItemModel + QStandardItem sort two types data independent:

The correct way would be to subclass QStandardItem and reimplement operator<

Which is what I would have done...

If yours works, where does sortChildren() say anything about being a "stable" re-sort?? I don't get how/why it would work, if I understand you correctly....

[VRonin]

@JonB said in How to use QStandardItemModel + QStandardItem sort two types data independent:

where does sortChildren() say anything about being a "stable" re-sort??

It doesn't say it but that's what the code does: https://code.woboq.org/qt5/qtbase/src/gui/itemmodels/qstandarditemmodel.cpp.html#_ZN20QStandardItemPrivate12sortChildrenEiN2Qt9SortOrderE (uses std::stable_sort)

[JonB]

@VRonin
LOL, internals... :)

But I still don't get it. Sorting by UserRole first is to get directories separated from files, right (or wrong)? But then don't they both have a DisplayRole value for their name? In which case the second sort would not have any "stables" to retain from the first one, every item has its own name for DisplayRole, no?

[VRonin]

That's correct, I inverted the roles order, good catch!

void MyOwnTreeModel::sortChilds(QStandardItem*pItem, Qt::SortOrder order)
{
if(!pItem) return;
const int oldSortRole = sortRole();
setSortRole(Qt::DisplayRole);
pItem->sortChildren(0,order);
setSortRole(Qt::UserRole);
pItem->sortChildren(0,order);
setSortRole(oldSortRole);
}

[JonB]

@VRonin
Ahhh, now that would make sense, with a stable second sort! Get them all alphabetical first, then separate as-is out into a directory versus file group.

It's reassuring to learn that somebody else but me does not actually test the code they propose... ;-)

[Aizzzz]

@VRonin @JonB It works well, great thanks! 😀