changing the checkstate of all the child item by checking the root item in Qtree widget

[jsulm]

@kook So, did you check https://doc.qt.io/qt-5/qtreewidgetitemiterator.html ? It shows how to iterate over child elements...

[kook]

@jsulm yes i read that document and tried using it by creating a simple code

QTreeWidgetItemIterator iterator(item);
    while (*iterator)
    {
        if ((*iterator)->checkState(0) == Qt::Checked)
        {
            qDebug()<< (*iterator)->text(0);
        }
        ++iterator;
    }

but i am unable to achieve want i wanted (checking all the child item by checking the root/parent) using this
what i am asking maybe a very simple thing but i am finding it difficult since i am a beginner please help me out thank you

[Bob64]

@kook you aren't changing anything in that loop. Don't you need to call setCheckState? See the documentation you have been pointed to; there is a very similar example.

[kook]

void MainWindow::on_treeWidget_itemChanged(QTreeWidgetItem *item, int column)
{
    QTreeWidgetItemIterator iterator(item);
    while( *iterator)
    {
        if ( (*iterator)->childCount() != 0)
        {
           if ( (*iterator)->checkState(column) == Qt::Checked)
           {
               for (int i = 0; i < item->childCount(); ++i)
               {
                   (*iterator)->child(i)->setCheckState(0, Qt::Checked);
               }
           }
        }
        ++iterator;
    }

ok i am able to do it now tell me is this the correct way of doing

[jsulm]

@kook Why iterator->child?!
First, check the check state of the parent, then apply that state on the children.

auto state = item->checkState(0);
QTreeWidgetItemIterator iterator(item);
while (*iterator)
{
        qDebug()<< (*iterator)->text(0);
        (*iterator)->setCheckState(0, state);
        ++iterator;
}

[kook]

@jsulm thank you i will try this

[JonB]

@jsulm
Does the (*iterator)->setCheckState(0, state); re-fire the on_treeWidget_itemChanged(QTreeWidgetItem *item, int column) for the child item's check state being changed? If so, good; if not, the OP will need a recursive function assuming he wants all descendants to get checked (and tree depth not limited to one level).

[jsulm]

@JonB said in changing the checkstate of all the child item by checking the root item in Qtree widget:

if not, the OP will need a recursive function assuming he wants all descendants to get checked

No, that's what QTreeWidgetItemIterator is doing.

[kook]

@jsulm the reason i used (*iterator)->child is i have multiple root in the tree i want only that particular root's child to be checked not the whole tree
the solution you have given is doing the latter

[jsulm]

@kook The solution I gave you iterates over all children of an item, NOT the whole tree.
If you want to change only some children of an item then you need a condition to decide which one to change, right? What is this condition? Can you explain what exactly should happen?

[kook]

@jsulm
when i change the message1 state it should change only its children check state
i tried the code you provided its changing the whole tree check state

i don't have any specific condition

[jsulm]

@kook said in changing the checkstate of all the child item by checking the root item in Qtree widget:

i tried the code you provided its changing the whole tree check state

Then you did something wrong.
What do you pass as item in this line QTreeWidgetItemIterator iterator(item); ?
It needs to be the item user clicked (in your example message1).

auto state = item->checkState(0);
QTreeWidgetItemIterator iterator(item);
while (*iterator)
{
        qDebug()<< (*iterator)->text(0);
        (*iterator)->setCheckState(0, state);
        ++iterator;
}

[kook]

@jsulm i am adding the code inside this function

void MainWindow::on_treeWidget_itemChanged(QTreeWidgetItem *item, int column)
{
}

[jsulm]

@kook You're right. This does not work as expected.
You will need to write a recursive method to iterate over all children of an item.

[jsulm]

@kook This works:

void MainWindow::on_treeWidget_itemChanged(QTreeWidgetItem *item, int column)
    for (int i = 0; i < item->childCount(); ++i) {
        qDebug() << item->child(i)->text(0);
        on_treeWidget_itemChanged(item->child(i), column);
    }
}

[kook]

@jsulm ok i will try thank you

[jsulm]

@kook I just fixed my code...

[kook]

@jsulm its not changing the checked state of children

[jsulm]

@kook said in changing the checkstate of all the child item by checking the root item in Qtree widget:

its not changing the checked state of children

Come on, that's because I did not add the code to change the checked state. Add that part:

void MainWindow::on_treeWidget_itemChanged(QTreeWidgetItem *item, int column)
    for (int i = 0; i < item->childCount(); ++i) {
        qDebug() << item->child(i)->text(0);
        item->child(i)->setCheckState(0, item->checkState(0));
        on_treeWidget_itemChanged(item->child(i), column);
    }
}

[kook]

@jsulm sorry i added that part its working
thank you for your time and solution