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[Solved]Find a Child in a QTreeView

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  • Z Offline
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    ZapB
    wrote on last edited by
    #4

    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.

    Nokia Certified Qt Specialist
    Interested in hearing about Qt related work

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    • G Offline
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      gronerth
      wrote on last edited by
      #5

      is QHash quicker?


      JETG

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        goetz
        wrote on last edited by
        #6

        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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          gronerth
          wrote on last edited by
          #7

          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

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            ZapB
            wrote on last edited by
            #8

            [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

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              goetz
              wrote on last edited by
              #9

              [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

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                gronerth
                wrote on last edited by
                #10

                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

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                  goetz
                  wrote on last edited by
                  #11

                  Yes, MatchRecursive makes the search look into the childs too.

                  http://www.catb.org/~esr/faqs/smart-questions.html

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                    gronerth
                    wrote on last edited by
                    #12

                    Ok, i didn't know, thanks for the advice..


                    JETG

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                      goetz
                      wrote on last edited by
                      #13

                      No problem, you're welcome - and that's what this forum is meant for :-)

                      Just let us know, if it works out for your case.

                      http://www.catb.org/~esr/faqs/smart-questions.html

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                        gronerth
                        wrote on last edited by
                        #14

                        yep, it works! thanks again...


                        JETG

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                          goetz
                          wrote on last edited by
                          #15

                          Again, you're welcome. You can mark the post as solved now: Just hit the edit link of the original post in this thread (it's located under your avatar right of the post) and prepend "[Solved]" to the title.

                          http://www.catb.org/~esr/faqs/smart-questions.html

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                            gronerth
                            wrote on last edited by
                            #16

                            done!


                            JETG

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