[Solved]Find a Child in a QTreeView

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Hi everyone,
Anyone can help me how to find a child in QTreeView. I have a QTreeView with one standardItem and that standardItem has many childs, i would like to find a child but by the Qt::DisplayRole or Qt::UserRole. I Have seen the doc. of the QStandardItem and it seems that the only way to find a child its by "row" and "column"...
Thanks in advance
JETG
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you can iterate over all items of the model and check the value. Afaik, there is no find or search.
Nokia Certified Qt Specialist.
Programming Is Like Sex: One mistake and you have to support it for the rest of your life. (Michael Sinz)
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I see...i thought that it could be another way....thankss
JETG
postedReputation: 1 | Posts: 76
As Gerolf said you'll need to iterate over the item hierarchy yourself. If you find yourself needing to do this many times, then I would consider constructing an index object that allows you to quickly lookup the needed items based upon the roles that you need to search upon.
Something like QMap<QVariant, QStandardItem*> might be useful and will allow you to do lookups of items in O(log(n)) rather than O(n) times. Of course it will be up to you to maintain this index as your data changes.
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is QHash quicker?
JETG
postedReputation: 1 | Posts: 76
As it seems that you use a "QStandardItemModel":http://doc.qt.nokia.com/4.7/qstandarditemmodel.html, have you tried "QStandardItemModel::findItems() ":http://doc.qt.nokia.com/4.7/qstandarditemmodel.html#findItems already?
If you need more control you can call "QAbstractItemModel::match() ":http://doc.qt.nokia.com/4.7/qabstractitemmodel.html#match. The latter returns only a QModelIndexList, you will have to peek the items with "QStandardItemModel::itemFromIndex() ":http://doc.qt.nokia.com/4.7/qstandarditemmodel.html#itemFromIndex then.
http://www.catb.org/~esr/faqs/smart-questions.html
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Hi volker,
Well i have tried with findItems (and match), but the standarditemmodel only has the root items not the childs....I had to iterate just as Gerolf says...
JETG
postedReputation: 1 | Posts: 76
[quote author="gronerth" date="1301602957"]is QHash quicker?[/quote]
Possibly but it does not store the items in an ordered manner which is sometimes useful to have if you need to iterate over them in some specific order. Depends upon the exact use case you wish to cater for.
Nokia Certified Qt Specialist
Interested in hearing about Qt related work
postedReputation: 40 | Posts: 1453
[quote author="gronerth" date="1301605423"]Hi volker,
Well i have tried with findItems (and match), but the standarditemmodel only has the root items not the childs....I had to iterate just as Gerolf says...[/quote]
How do you create a hierarchy then? And what model do you use?
You can add Qt::MatchRecursive to the search flags of match and findItems.
http://www.catb.org/~esr/faqs/smart-questions.html
postedReputation: 38 | Posts: 5422
Well the item root:
@
QStandardItem *root = new QStandardItem("rootItem");
model->setItem(0,root);
@
The childs items
@
root->setChild(row,device2Add);
@
I haven't trie with Qt::MatchRecursive, does it search too in the childs of each item?
JETG
postedReputation: 1 | Posts: 76
Yes, MatchRecursive makes the search look into the childs too.
http://www.catb.org/~esr/faqs/smart-questions.html
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