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Use setData() from QML

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  • sierdzioS sierdzio

    The standard approach in QML is to not use data() and setData(). You should use model.roleName instead - bot for reading and writing.

    If you have to use setData(), this should work:

    modelId.setData(modelId.index(row, column), value, role)
    

    You need to create the index from the model. Using just integer won't work.

    E Offline
    E Offline
    ed_robcont_
    wrote on last edited by
    #5

    @sierdzio said in Use setData() from QML:

    The standard approach in QML is to not use data() and setData(). You should use model.roleName instead - bot for reading and writing.

    Ok, got it. But something is not working and I don't understand where and why.
    When I read data using model.plotted or similar, I always get undefined.
    Instead, when I try to replace some data, e.g. with model.plotted = true, the function setData() is never entered (I observed that on debug).

    If you have to use setData(), this should work:

    modelId.setData(modelId.index(row, column), value, role)
    

    You need to create the index from the model. Using just integer won't work.

    I've tried also this approach. In my previous response I used var index = model.index(i, 1) to iterate through indexes, but without success.

    May be a problem that my DataDelegate is in another QML file?

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    • E Offline
      E Offline
      ed_robcont_
      wrote on last edited by ed_robcont_
      #6

      DONE!!
      I was picking an invalid index using 1 instead of 0 for column. Also the role values was wrong.
      Here below the "solution".

      // Read
      dmodel.data(dmodel.index(n, 0), DataModel.PlottedRole)
      
      // Write: 
      dmodel.setData(dmodel.index(n, 0), checked, DataModel.PlottedRole)
      

      Last question. By using index(row, column) is the only way to access to the n item of the list? Or I should implement my "custom getter" like this?

      DataItem DataModel::get(int row)
      {
          return mList.at(row);
      }
      
      sierdzioS 1 Reply Last reply
      1
      • 6thC6 Offline
        6thC6 Offline
        6thC
        wrote on last edited by
        #7
        This post is deleted!
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        • E ed_robcont_

          DONE!!
          I was picking an invalid index using 1 instead of 0 for column. Also the role values was wrong.
          Here below the "solution".

          // Read
          dmodel.data(dmodel.index(n, 0), DataModel.PlottedRole)
          
          // Write: 
          dmodel.setData(dmodel.index(n, 0), checked, DataModel.PlottedRole)
          

          Last question. By using index(row, column) is the only way to access to the n item of the list? Or I should implement my "custom getter" like this?

          DataItem DataModel::get(int row)
          {
              return mList.at(row);
          }
          
          sierdzioS Offline
          sierdzioS Offline
          sierdzio
          Moderators
          wrote on last edited by
          #8

          @ed_robcont_ said in Use setData() from QML:

          DONE!!
          I was picking an invalid index using 1 instead of 0 for column. Also the role values was wrong.

          Thanks for posting.

          DataItem DataModel::get(int row)
          {
              return mList.at(row);
          }
          

          Since you're not using the standard approach anyway, I'd say it's up to you. A simple getter like this makes absolute sense.

          (Z(:^

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          • sierdzioS sierdzio

            @ed_robcont_ said in Use setData() from QML:

            DONE!!
            I was picking an invalid index using 1 instead of 0 for column. Also the role values was wrong.

            Thanks for posting.

            DataItem DataModel::get(int row)
            {
                return mList.at(row);
            }
            

            Since you're not using the standard approach anyway, I'd say it's up to you. A simple getter like this makes absolute sense.

            E Offline
            E Offline
            ed_robcont_
            wrote on last edited by
            #9

            @sierdzio

            It's working, so it's ok for me. Anyway, I'm still not understanding how the standard approach works.

            Task: Modify the temperature field in row 3 when a signal is emitted from another QML component.
            How to access this field in the standard way, without using setData()?

            sierdzioS 1 Reply Last reply
            0
            • E ed_robcont_

              @sierdzio

              It's working, so it's ok for me. Anyway, I'm still not understanding how the standard approach works.

              Task: Modify the temperature field in row 3 when a signal is emitted from another QML component.
              How to access this field in the standard way, without using setData()?

              sierdzioS Offline
              sierdzioS Offline
              sierdzio
              Moderators
              wrote on last edited by
              #10

              @ed_robcont_ said in Use setData() from QML:

              Task: Modify the temperature field in row 3 when a signal is emitted from another QML component.
              How to access this field in the standard way, without using setData()?

              Signal emitted from QML should go to your model. Then model should emit dataChanged() and this will update all affected delegates on QML side.

              (Z(:^

              E 1 Reply Last reply
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              • sierdzioS sierdzio

                @ed_robcont_ said in Use setData() from QML:

                Task: Modify the temperature field in row 3 when a signal is emitted from another QML component.
                How to access this field in the standard way, without using setData()?

                Signal emitted from QML should go to your model. Then model should emit dataChanged() and this will update all affected delegates on QML side.

                E Offline
                E Offline
                ed_robcont_
                wrote on last edited by ed_robcont_
                #11

                @sierdzio said in Use setData() from QML:

                Signal emitted from QML should go to your model. Then model should emit dataChanged() and this will update all affected delegates on QML side.

                Ok, it works, thank you!

                One more thing, it'll be the last I promise.
                Actually, DataModel is the owner of my list. What I want is to add it from another class, i.e. DataServer. I tried this code but is not working. Any suggestion?

                @DataServer.cpp

                void DataServer::showList()
                {
                    QVector<DataItem*> list;
                    list.append(new DataItem(...);
                    list.append(new DataItem(...);
                    list.append(new DataItem(...);
                
                    emit listChanged(QVariant::fromValue(list));
                }
                

                @DataModel

                void DataModel::setList(QVariant list)
                {
                    m_list = list;
                }
                

                @QML

                Button {
                    id: btn
                    onPressed: dserver.showList()
                }
                
                DataServer {
                    id: dserver
                    onListChanged: dmodel.setList(list)
                }
                
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                • sierdzioS Offline
                  sierdzioS Offline
                  sierdzio
                  Moderators
                  wrote on last edited by
                  #12

                  void DataServer::setList(QVariant list)
                  {
                  m_list = list;
                  }

                  You don't have emit dataChanged() here. Or, in this case, you should probably do:

                  beginResetModel();
                  m_list = list;
                  endResetModel();
                  

                  (Z(:^

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                  • sierdzioS sierdzio

                    void DataServer::setList(QVariant list)
                    {
                    m_list = list;
                    }

                    You don't have emit dataChanged() here. Or, in this case, you should probably do:

                    beginResetModel();
                    m_list = list;
                    endResetModel();
                    
                    E Offline
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                    ed_robcont_
                    wrote on last edited by ed_robcont_
                    #13

                    @sierdzio said in Use setData() from QML:

                    You don't have emit dataChanged() here. Or, in this case, you should probably do:

                    beginResetModel();
                    m_list = list;
                    endResetModel();
                    

                    Yes. No signal dataChanged() should be emitted.
                    I did the same you suggested, but I've getting this error.

                    qrc:/main.qml:21: Error: Unknown method parameter type: QVector<DataItem*>
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                    • E Offline
                      E Offline
                      ed_robcont_
                      wrote on last edited by
                      #14

                      Done, by inserting rows one by one.

                      1 Reply Last reply
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