CODEWITHSUNDEEP
pythonqtlistcrashqtreewidget
Austen Fano
Austen Fano

Reputation: 11

PyQT crash ( underlying C/C++ object has been deleted ) "after" clear QTreeWidget

i try to build a realtime search for a QTreeWidget, that means that i have a QLineEdit and when im typing, i will filter the shown results in the QTreeWidget.

At the moment i get the "still shown itmes" with QTreeWidget.findItems() 

foundItems  = mainForm.ui.treeShips.findItems(text,QtCore.Qt.MatchContains)

later i clear the QTreeWidget ( mainForm.ui.treeShips) with

mainForm.ui.treeShips.clear()

then i want to add the "still shown items" with 

mainForm.ui.treeShips.addTopLevelItems(foundItems)

but then the programm crashes with the "underlying C/C++ object has been deleted" error

My first idea is, that with clearing the treeShips, the content of foundItems got cleared too cause the objects of foundItems ( print(foundItems) ) and the objects of treeShips have the same adresses and when the programm want to work with this list, it crash.

Does someone know how to fix it, or have a better idea to apply such a "search filter" ?

( i hope i could describe my problem correctly :) )

thanks and best regards

Upvotes: 0

Views: 973

Answers (2)

Austen Fano
Austen Fano

Reputation: 11

i found a workaround based on the 2nd idea from Neox.

I iterate all items in the tree and set the hidden flag on true ( setHidden(True) ) and then i iterate the foundItems and set the hidden flag on false ( i think that works, cause both lists have the same adresses )

for item in mainForm.ui.treeShips.findItems("",QtCore.Qt.MatchContains):
    item.setHidden(True)

for item in foundItems:
    item.setHidden(False)

But i dont know if that isnt a dirty way, but it works :)

I hope that this will help other ppl who have the same problem.

Upvotes: 1

Neox
Neox

Reputation: 2004

Whenever you call clear function on a QTreeWidgetItem the items are deleted so the error you get is no surprise. You can see it in the following excerpt of the QTreeWidget implementation:

void QTreeWidget::clear()
{
    Q_D(QTreeWidget);
    selectionModel()->clear();
    //the treeModel here is QTreeModel, refer to snippet below
    d->treeModel()->clear();
}


void QTreeModel::clear()
{
    SkipSorting skipSorting(this);
    for (int i = 0; i < rootItem->childCount(); ++i) {
        QTreeWidgetItem *item = rootItem->children.at(i);
        item->par = 0;
        item->view = 0;
        delete item;
    }
....
}

To you actual question about search implementation. First here is a nice snippet for implementation of the actual search functionality (not real-time). (sorry its c++ but i hope its fine).

To perform a real time search you have to connect a void textChanged(const QString & text) signal from QLineEdit to a slot where the search is performed.

I hope that answers your question

Upvotes: 0

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