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How to update QTableView when rows are inserted to it

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  • RatzzR Ratzz

    @kshegunov
    Thanks for the reply.
    But doc says

    Note: This is a private signal. It can be used in signal connections but cannot be emitted by the user.
    

    What does this mean?

    kshegunovK Offline
    kshegunovK Offline
    kshegunov
    Moderators
    wrote on last edited by
    #4

    @Ratzz
    It means it can't be emitted from the user of the class. Since you're not the user of the class, but rather the designer, I think you should just ignore the note. ;)

    Read and abide by the Qt Code of Conduct

    RatzzR 1 Reply Last reply
    0
    • kshegunovK kshegunov

      @Ratzz
      It means it can't be emitted from the user of the class. Since you're not the user of the class, but rather the designer, I think you should just ignore the note. ;)

      RatzzR Offline
      RatzzR Offline
      Ratzz
      wrote on last edited by
      #5

      @kshegunov
      It asks for QPrivateSignal http://postimg.org/image/bjpuc4bep/

      --Alles ist gut.

      kshegunovK 2 Replies Last reply
      0
      • RatzzR Ratzz

        @kshegunov
        It asks for QPrivateSignal http://postimg.org/image/bjpuc4bep/

        kshegunovK Offline
        kshegunovK Offline
        kshegunov
        Moderators
        wrote on last edited by
        #6

        @Ratzz
        Oops, sorry. The note above the one you cited states:

        It can only be emitted by the QAbstractItemModel implementation, and cannot be explicitly emitted in subclass code.
        

        Hm, in that case I'm not sure ... The documentation is somewhat cryptic whether endInsertRows() actually emits the aforementioned signal ...

        Read and abide by the Qt Code of Conduct

        RatzzR 1 Reply Last reply
        0
        • RatzzR Ratzz

          @kshegunov
          It asks for QPrivateSignal http://postimg.org/image/bjpuc4bep/

          kshegunovK Offline
          kshegunovK Offline
          kshegunov
          Moderators
          wrote on last edited by
          #7

          @Ratzz
          Possibly, you could try implementing QAbstractItemModel::dropMimeData without intercepting the drop event?

          Read and abide by the Qt Code of Conduct

          1 Reply Last reply
          2
          • kshegunovK kshegunov

            @Ratzz
            Oops, sorry. The note above the one you cited states:

            It can only be emitted by the QAbstractItemModel implementation, and cannot be explicitly emitted in subclass code.
            

            Hm, in that case I'm not sure ... The documentation is somewhat cryptic whether endInsertRows() actually emits the aforementioned signal ...

            RatzzR Offline
            RatzzR Offline
            Ratzz
            wrote on last edited by Ratzz
            #8

            @kshegunov
            The beginInsertRows doc http://doc.qt.io/qt-4.8/qabstractitemmodel.html#beginInsertRows says

            Note: This function emits the rowsAboutToBeInserted() signal which connected views (or proxies) must handle before the data is inserted. Otherwise, the views may end up in an invalid state.
            

            Will it help?

            --Alles ist gut.

            kshegunovK 1 Reply Last reply
            0
            • RatzzR Ratzz

              @kshegunov
              The beginInsertRows doc http://doc.qt.io/qt-4.8/qabstractitemmodel.html#beginInsertRows says

              Note: This function emits the rowsAboutToBeInserted() signal which connected views (or proxies) must handle before the data is inserted. Otherwise, the views may end up in an invalid state.
              

              Will it help?

              kshegunovK Offline
              kshegunovK Offline
              kshegunov
              Moderators
              wrote on last edited by kshegunov
              #9

              @Ratzz
              Yes, I saw that, but this is to notify the view insertions will be happening. The question is whether endInsertRows() emits rowsInserted() thus telling the view the insertion has finished and it can actually update itself. Unfortunately, the documentation doesn't state anything specific about endInsertRows(), unless I completely missed it ...

              PS. I just noticed something in your code:

              QTreeView * view= dynamic_cast<QTreeView*>(event->source());
              

              Is this a typo?

              Read and abide by the Qt Code of Conduct

              RatzzR 1 Reply Last reply
              1
              • SGaistS Offline
                SGaistS Offline
                SGaist
                Lifetime Qt Champion
                wrote on last edited by
                #10

                Hi,

                The documentation doesn't specify but the implementation does emit rowsInserted. However in this case insertRows doesn't do anything so I wonder if there isn't a caching mechanism that avoids to update the view if in fact nothing has changed.

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

                RatzzR kshegunovK 2 Replies Last reply
                1
                • kshegunovK kshegunov

                  @Ratzz
                  Yes, I saw that, but this is to notify the view insertions will be happening. The question is whether endInsertRows() emits rowsInserted() thus telling the view the insertion has finished and it can actually update itself. Unfortunately, the documentation doesn't state anything specific about endInsertRows(), unless I completely missed it ...

                  PS. I just noticed something in your code:

                  QTreeView * view= dynamic_cast<QTreeView*>(event->source());
                  

                  Is this a typo?

                  RatzzR Offline
                  RatzzR Offline
                  Ratzz
                  wrote on last edited by
                  #11

                  @kshegunov said:

                  Is this a typo?

                  I drag the items from another QTreeView .The cast is for that..
                  Did you mean that?

                  --Alles ist gut.

                  1 Reply Last reply
                  0
                  • SGaistS SGaist

                    Hi,

                    The documentation doesn't specify but the implementation does emit rowsInserted. However in this case insertRows doesn't do anything so I wonder if there isn't a caching mechanism that avoids to update the view if in fact nothing has changed.

                    RatzzR Offline
                    RatzzR Offline
                    Ratzz
                    wrote on last edited by
                    #12

                    @SGaist said:
                    Thanks for the reply.
                    So there is no way with insertRows?

                    --Alles ist gut.

                    1 Reply Last reply
                    0
                    • SGaistS SGaist

                      Hi,

                      The documentation doesn't specify but the implementation does emit rowsInserted. However in this case insertRows doesn't do anything so I wonder if there isn't a caching mechanism that avoids to update the view if in fact nothing has changed.

                      kshegunovK Offline
                      kshegunovK Offline
                      kshegunov
                      Moderators
                      wrote on last edited by kshegunov
                      #13

                      @SGaist

                      However in this case insertRows doesn't do anything so I wonder if there isn't a caching mechanism that avoids to update the view if in fact nothing has changed.

                      After a quick look (without pretense to be complete) I couldn't clearly see any such caching done.
                      Here's what I peeked at (for Qt 5.6):
                      http://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/itemmodels/qabstractitemmodel.cpp#n2601
                      http://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/itemmodels/qabstractitemmodel.cpp#n582

                      @Ratzz

                      I drag the items from another QTreeView .The cast is for that..
                      Did you mean that?

                      Indeed I did. Have you considered handling the drag/drop events through the ordinary mechanism? Serializing on drag, then deserializing the mime data on drop?

                      Read and abide by the Qt Code of Conduct

                      RatzzR 1 Reply Last reply
                      1
                      • kshegunovK kshegunov

                        @SGaist

                        However in this case insertRows doesn't do anything so I wonder if there isn't a caching mechanism that avoids to update the view if in fact nothing has changed.

                        After a quick look (without pretense to be complete) I couldn't clearly see any such caching done.
                        Here's what I peeked at (for Qt 5.6):
                        http://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/itemmodels/qabstractitemmodel.cpp#n2601
                        http://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/itemmodels/qabstractitemmodel.cpp#n582

                        @Ratzz

                        I drag the items from another QTreeView .The cast is for that..
                        Did you mean that?

                        Indeed I did. Have you considered handling the drag/drop events through the ordinary mechanism? Serializing on drag, then deserializing the mime data on drop?

                        RatzzR Offline
                        RatzzR Offline
                        Ratzz
                        wrote on last edited by
                        #14

                        @kshegunov said:

                        Serializing on drag, then deserializing the mime data on drop?

                        No i have not considered this part.

                        --Alles ist gut.

                        kshegunovK 1 Reply Last reply
                        0
                        • SGaistS Offline
                          SGaistS Offline
                          SGaist
                          Lifetime Qt Champion
                          wrote on last edited by
                          #15

                          @kshegunov : I mean't view side caching.

                          @Ratzz currently you are not inserting anything through it. Like @kshegunov suggested, implement the drag and drop through the mechanism provided for model/view classes. It's described here

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

                          RatzzR 1 Reply Last reply
                          0
                          • SGaistS SGaist

                            @kshegunov : I mean't view side caching.

                            @Ratzz currently you are not inserting anything through it. Like @kshegunov suggested, implement the drag and drop through the mechanism provided for model/view classes. It's described here

                            RatzzR Offline
                            RatzzR Offline
                            Ratzz
                            wrote on last edited by
                            #16

                            @SGaist
                            I will try to implement through (link you provided ) this.

                            --Alles ist gut.

                            1 Reply Last reply
                            0
                            • RatzzR Ratzz

                              @kshegunov said:

                              Serializing on drag, then deserializing the mime data on drop?

                              No i have not considered this part.

                              kshegunovK Offline
                              kshegunovK Offline
                              kshegunov
                              Moderators
                              wrote on last edited by kshegunov
                              #17

                              @Ratzz

                              No i have not considered this part.

                              Then I suggest you try it out. It may prove to be easier and better behaved than pulling the records directly from the tree widget. As for your current implementation, I'm at a loss why it doesn't work. Maybe the tree view is losing the selection when dragging and the selection model returns no records?

                              @SGaist

                              I mean't view side caching.

                              I see, well I didn't look at the view (obviously) but I suppose it's possible.

                              Read and abide by the Qt Code of Conduct

                              RatzzR 1 Reply Last reply
                              1
                              • mrjjM Offline
                                mrjjM Offline
                                mrjj
                                Lifetime Qt Champion
                                wrote on last edited by
                                #18

                                Hi
                                I am still wondering. Sorry.
                                Lets say If I dont have drag&drop.

                                I simply append to my internal list used in model.

                                How will I tell the view(s) that?

                                I though dataChanged would do it but not even begin/endInsertRow
                                does it.

                                Thanks

                                kshegunovK 1 Reply Last reply
                                0
                                • kshegunovK kshegunov

                                  @Ratzz

                                  No i have not considered this part.

                                  Then I suggest you try it out. It may prove to be easier and better behaved than pulling the records directly from the tree widget. As for your current implementation, I'm at a loss why it doesn't work. Maybe the tree view is losing the selection when dragging and the selection model returns no records?

                                  @SGaist

                                  I mean't view side caching.

                                  I see, well I didn't look at the view (obviously) but I suppose it's possible.

                                  RatzzR Offline
                                  RatzzR Offline
                                  Ratzz
                                  wrote on last edited by
                                  #19

                                  @kshegunov said:

                                  Maybe the tree view is losing the selection when dragging and the selection model returns no records?

                                  I don't think so because the rowCount is getting updated as and when the new drop takes place.

                                  --Alles ist gut.

                                  1 Reply Last reply
                                  0
                                  • mrjjM mrjj

                                    Hi
                                    I am still wondering. Sorry.
                                    Lets say If I dont have drag&drop.

                                    I simply append to my internal list used in model.

                                    How will I tell the view(s) that?

                                    I though dataChanged would do it but not even begin/endInsertRow
                                    does it.

                                    Thanks

                                    kshegunovK Offline
                                    kshegunovK Offline
                                    kshegunov
                                    Moderators
                                    wrote on last edited by
                                    #20

                                    @mrjj

                                    I simply append to my internal list used in model.

                                    I'm by no means an expert, but possibly calling submit() (I don't know if it works I'm just guessing)?

                                    Read and abide by the Qt Code of Conduct

                                    1 Reply Last reply
                                    0
                                    • SGaistS Offline
                                      SGaistS Offline
                                      SGaist
                                      Lifetime Qt Champion
                                      wrote on last edited by
                                      #21

                                      On a side note, your rowCount implementation should rather return the size of your TableList, that way it's one less thing to manage.

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

                                      RatzzR 1 Reply Last reply
                                      1
                                      • SGaistS SGaist

                                        On a side note, your rowCount implementation should rather return the size of your TableList, that way it's one less thing to manage.

                                        RatzzR Offline
                                        RatzzR Offline
                                        Ratzz
                                        wrote on last edited by
                                        #22

                                        @SGaist
                                        Yes ,now i am returning the size of TableList .

                                        --Alles ist gut.

                                        RatzzR 1 Reply Last reply
                                        1
                                        • RatzzR Ratzz

                                          @SGaist
                                          Yes ,now i am returning the size of TableList .

                                          RatzzR Offline
                                          RatzzR Offline
                                          Ratzz
                                          wrote on last edited by Ratzz
                                          #23

                                          In dropEvent called a new function from model which stores all the parameter of item when droped and emitted layoutAboutToBeChanged() before appending to my TableList and then emitted layoutChanged() which worked for me.

                                          Thanks to @kshegunov , @SGaist , @mrjj for the help.

                                          --Alles ist gut.

                                          1 Reply Last reply
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