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QFileSystemModel and QSortFilterProxyModel - root index is not preserved

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c++qfilesystemmodeqsortfilterproxfiltering
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  • M Offline
    M Offline
    MasterBLB
    wrote on 28 Jun 2019, 09:48 last edited by
    #9

    And that's why I've written the example within around 60s, as requested. I hope it fulfills expectations, but if needed feel free to ask about implementation details of models, though as mentioned there isn't anything related to manipulating root index.

    1 Reply Last reply
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    • M Offline
      M Offline
      mrjj
      Lifetime Qt Champion
      wrote on 28 Jun 2019, 15:40 last edited by
      #10

      Hi
      I can confirm it get the same result on Qt5.12.3 and Qt5.9
      so at least we can say its not a local bug of sorts.
      alt text

      #include <QApplication>
      #include <QFileSystemModel>
      #include <QSortFilterProxyModel>
      #include <QTreeView>
      
      int main(int argc, char *argv[])
      {
          QApplication a(argc, argv);
      
          QTreeView treeView;
      
          QFileSystemModel navigationModel;
          navigationModel.setFilter(QDir::AllDirs | QDir::NoDotAndDotDot | QDir::Files);
          navigationModel.setNameFilterDisables(true);
          QString root("C:/Qt/5.12.3/msvc2017_64");
          navigationModel.setRootPath(root);
      
          QSortFilterProxyModel filteringModel;
          filteringModel.setSourceModel(&navigationModel);
          filteringModel.setRecursiveFilteringEnabled(true);
          filteringModel.setFilterCaseSensitivity(Qt::CaseInsensitive);
      
          treeView.setModel(&filteringModel);
          treeView.setRootIndex(filteringModel.mapFromSource(navigationModel.index(root)));
      
          filteringModel.setFilterFixedString("Lib");
      
          treeView.show();
      
          return a.exec();
      }
      
      
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      • S Offline
        S Offline
        SGaist
        Lifetime Qt Champion
        wrote on 28 Jun 2019, 19:01 last edited by
        #11

        As @mrjj I can reproduce that on macOS with a recent build of Qt.

        You should check the bug report system to see if there's already something related. If not, then please consider opening a new report providing that minimal compilable example.

        Interested in AI ? www.idiap.ch
        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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        3
        • M Offline
          M Offline
          MasterBLB
          wrote on 28 Jun 2019, 20:10 last edited by
          #12

          Oh crap, tough luck :/ How to open a Qt bug report?

          M 1 Reply Last reply 28 Jun 2019, 20:12
          0
          • M MasterBLB
            28 Jun 2019, 20:10

            Oh crap, tough luck :/ How to open a Qt bug report?

            M Offline
            M Offline
            mrjj
            Lifetime Qt Champion
            wrote on 28 Jun 2019, 20:12 last edited by
            #13

            @MasterBLB
            Hi
            Well you just go there and login with the credentials you use here.
            A good read is
            https://wiki.qt.io/Reporting_Bugs

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            2
            • M Offline
              M Offline
              MasterBLB
              wrote on 2 Jul 2019, 08:47 last edited by
              #14

              @mrjj , @SGaist - have you reported the bug? If not I will try when I'll go back home after work.

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              • S Offline
                S Offline
                SGaist
                Lifetime Qt Champion
                wrote on 2 Jul 2019, 08:51 last edited by
                #15

                Personally, I didn't. Since you found it, the honour is yours :)

                Interested in AI ? www.idiap.ch
                Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                1
                • M Offline
                  M Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on 2 Jul 2019, 09:03 last edited by
                  #16

                  Hi
                  nope, if i had made report, i would have linked url here :)
                  So please do.

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                  0
                  • V Offline
                    V Offline
                    VRonin
                    wrote on 2 Jul 2019, 09:15 last edited by
                    #17

                    I don't think it's a bug.
                    setRootIndex is a method of the view. The model has no way of knowing (and shouldn't know) what a view is using as root. The filter set on the proxy applies to the whole model. If the index used as root by a view gets filtered out it's only natural for a view to revert to using QModelIndex() as root.

                    What you need is a proxy model that implements the setRootIndex functionality at the model level. This is on the list of nice-things-I-would-like-to-add-to-Qt-models and it's a fairly easy one to do but I need to find time for it :(

                    "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                    ~Napoleon Bonaparte

                    On a crusade to banish setIndexWidget() from the holy land of Qt

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                    • M Offline
                      M Offline
                      MasterBLB
                      wrote on 2 Jul 2019, 18:34 last edited by
                      #18

                      ...and now I'm confused :/

                      JonBJ 1 Reply Last reply 2 Jul 2019, 18:41
                      0
                      • M MasterBLB
                        2 Jul 2019, 18:34

                        ...and now I'm confused :/

                        JonBJ Offline
                        JonBJ Offline
                        JonB
                        wrote on 2 Jul 2019, 18:41 last edited by
                        #19

                        @MasterBLB
                        Confused in what way? I have just read this thread and what @VRonin has written seems correct to me. Are you not understanding what he is saying, or what?

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                        • M Offline
                          M Offline
                          MasterBLB
                          wrote on 3 Jul 2019, 07:27 last edited by
                          #20

                          In the way such behavior breaks SOLID substitute rule - I can't use descendant class QFileSystemModel like it was its base class QAbstractItemModel in QSortFilterProxyModel. While not a 100% bug it's definitely a serious design flaw, and worth to be reported. But where?

                          jsulmJ V 2 Replies Last reply 3 Jul 2019, 08:01
                          0
                          • M MasterBLB
                            3 Jul 2019, 07:27

                            In the way such behavior breaks SOLID substitute rule - I can't use descendant class QFileSystemModel like it was its base class QAbstractItemModel in QSortFilterProxyModel. While not a 100% bug it's definitely a serious design flaw, and worth to be reported. But where?

                            jsulmJ Offline
                            jsulmJ Offline
                            jsulm
                            Lifetime Qt Champion
                            wrote on 3 Jul 2019, 08:01 last edited by
                            #21

                            @MasterBLB said in QFileSystemModel and QSortFilterProxyModel - root index is not preserved:

                            But where?

                            In Qt bug tracker https://bugreports.qt.io/secure/Dashboard.jspa
                            Also you can talk to Qt developers on their mailing list.

                            https://forum.qt.io/topic/113070/qt-code-of-conduct

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                            • M MasterBLB
                              3 Jul 2019, 07:27

                              In the way such behavior breaks SOLID substitute rule - I can't use descendant class QFileSystemModel like it was its base class QAbstractItemModel in QSortFilterProxyModel. While not a 100% bug it's definitely a serious design flaw, and worth to be reported. But where?

                              V Offline
                              V Offline
                              VRonin
                              wrote on 3 Jul 2019, 08:44 last edited by VRonin 7 Mar 2019, 10:08
                              #22

                              breaks SOLID

                              It doesn't. In fact, if it worked as you expected it would break SOLID

                              it's definitely a serious design flaw

                              Sorry to be brutal: No, it's not a flaw, you just didn't understand the design of model/views.
                              To help you get a better idea of what is going on, try use the same model with 2 different treeviews. In only one of the view call setRootIndex, and then trigger the filtering.

                              "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                              ~Napoleon Bonaparte

                              On a crusade to banish setIndexWidget() from the holy land of Qt

                              1 Reply Last reply
                              2
                              • B Offline
                                B Offline
                                Brad1111
                                wrote on 12 Feb 2025, 22:50 last edited by
                                #23

                                Im actually encountering the very same issue.
                                Clearly it wont be fixed by Qt since Ive even seen posts about this issue back from 2011.
                                Could someone help me a little bit by telling me what to do please ?

                                @VRonin You were the most precise, suggesting to implements the setRootIndex to the proxymodel, but I would still require a bit more info if I am to do it on my own please :D

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                                0
                                • jeremy_kJ Offline
                                  jeremy_kJ Offline
                                  jeremy_k
                                  wrote on 13 Feb 2025, 02:51 last edited by
                                  #24

                                  It looks like @VRonin implemented his idea. See https://github.com/VSRonin/QtModelUtilities/blob/master/READMERootIndexProxyModel.md

                                  Asking a question about code? http://eel.is/iso-c++/testcase/

                                  B 1 Reply Last reply 13 Feb 2025, 04:28
                                  1
                                  • jeremy_kJ jeremy_k
                                    13 Feb 2025, 02:51

                                    It looks like @VRonin implemented his idea. See https://github.com/VSRonin/QtModelUtilities/blob/master/READMERootIndexProxyModel.md

                                    B Offline
                                    B Offline
                                    Brad1111
                                    wrote on 13 Feb 2025, 04:28 last edited by
                                    #25

                                    @jeremy_k Wow, Awesome ! Thanks for your answer and massive props to @VRonin !

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