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Dynamic Upadate of data to a ListModel

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  • raven-worxR raven-worx

    @m.sue said in Dynamic Upadate of data to a ListModel:

    Ah, I see, then they probably emit the *AboutToBe* signals, as somehow, of course, the widget must know about these actions.

    yes, the QAbstractItemView of course does connect to those signals. If you have a custom object/widget, you would also need to connect to those signals.

    @saitej said in Dynamic Upadate of data to a ListModel:

    I didn't get you. If I need to change the existing data, how do i do it with out datachanged() signal

    i said: you only need in the case existing data has changed

    saitejS Offline
    saitejS Offline
    saitej
    wrote on last edited by
    #11

    @raven-worx

    void QAbstractItemModel::dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles = QVector<int> ())
    

    Is this used to update the entire model or Can it be used to update a specific item in the listview? If It can be used to update a specific item then what are the arguments (instead of bootrom right)?

    Thanks!!

    raven-worxR 1 Reply Last reply
    0
    • saitejS saitej

      @raven-worx

      void QAbstractItemModel::dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles = QVector<int> ())
      

      Is this used to update the entire model or Can it be used to update a specific item in the listview? If It can be used to update a specific item then what are the arguments (instead of bootrom right)?

      Thanks!!

      raven-worxR Offline
      raven-worxR Offline
      raven-worx
      Moderators
      wrote on last edited by raven-worx
      #12

      @saitej
      if it's just a single cell, then topLeft and bottomRight are the same index.
      If you want to update the whole row, then topLeft is QModelIndex(row,0) and bottomRight is QModelIndex(row,colCount-1).
      Also it is possible to set topLeft to QModelIndex(0,0) and bottomRight to QModelIndex(rowCount-1,colCount-1) to update the whole table/list.

      Note that ranges are only supported when topLeft and bottomRight have the same parent index. So as long as you don't use your model in a treeview your are fine.

      --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
      If you have a question please use the forum so others can benefit from the solution in the future

      saitejS 2 Replies Last reply
      1
      • raven-worxR raven-worx

        @saitej
        if it's just a single cell, then topLeft and bottomRight are the same index.
        If you want to update the whole row, then topLeft is QModelIndex(row,0) and bottomRight is QModelIndex(row,colCount-1).
        Also it is possible to set topLeft to QModelIndex(0,0) and bottomRight to QModelIndex(rowCount-1,colCount-1) to update the whole table/list.

        Note that ranges are only supported when topLeft and bottomRight have the same parent index. So as long as you don't use your model in a treeview your are fine.

        saitejS Offline
        saitejS Offline
        saitej
        wrote on last edited by
        #13

        @raven-worx

        Thanks a lot!!

        1 Reply Last reply
        0
        • raven-worxR raven-worx

          @saitej
          if it's just a single cell, then topLeft and bottomRight are the same index.
          If you want to update the whole row, then topLeft is QModelIndex(row,0) and bottomRight is QModelIndex(row,colCount-1).
          Also it is possible to set topLeft to QModelIndex(0,0) and bottomRight to QModelIndex(rowCount-1,colCount-1) to update the whole table/list.

          Note that ranges are only supported when topLeft and bottomRight have the same parent index. So as long as you don't use your model in a treeview your are fine.

          saitejS Offline
          saitejS Offline
          saitej
          wrote on last edited by saitej
          #14

          @raven-worx

          Hi

          I am trying to connect a property change signal to datachanged signal through the following code.

          for(int i=0;i<model.rowCount();i++)
              {
                   if(model.data(model.index(i),UAVDataModel::NameRole).toString() == "Initial Polygon Area" ){
                       connect(&av1,SIGNAL(initialPolygonAreaChanged(qreal)),&model,SIGNAL(dataChanged(model.index(i),model.index(i))));
                   }
          
              }
          

          I am getting an error

          QObject::connect: No such signal DataModel::dataChanged(model.index(i),model.index(i))

          Note: I have not redeclared the signal in the model as it is inherited from QAbstractListModel

          raven-worxR 1 Reply Last reply
          0
          • saitejS saitej

            @raven-worx

            Hi

            I am trying to connect a property change signal to datachanged signal through the following code.

            for(int i=0;i<model.rowCount();i++)
                {
                     if(model.data(model.index(i),UAVDataModel::NameRole).toString() == "Initial Polygon Area" ){
                         connect(&av1,SIGNAL(initialPolygonAreaChanged(qreal)),&model,SIGNAL(dataChanged(model.index(i),model.index(i))));
                     }
            
                }
            

            I am getting an error

            QObject::connect: No such signal DataModel::dataChanged(model.index(i),model.index(i))

            Note: I have not redeclared the signal in the model as it is inherited from QAbstractListModel

            raven-worxR Offline
            raven-worxR Offline
            raven-worx
            Moderators
            wrote on last edited by
            #15

            @saitej
            thats not how signal/slot connections work.
            Rather you should connect the model's dataChanged() signal to a slot of yours, and in the slot check the passed index if it's the row/column you want.

            --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
            If you have a question please use the forum so others can benefit from the solution in the future

            saitejS 1 Reply Last reply
            0
            • raven-worxR raven-worx

              @saitej
              thats not how signal/slot connections work.
              Rather you should connect the model's dataChanged() signal to a slot of yours, and in the slot check the passed index if it's the row/column you want.

              saitejS Offline
              saitejS Offline
              saitej
              wrote on last edited by
              #16

              @raven-worx

              I am not editing the data, it is only displaying data from a source. So connecting datachanged signal to a slot does not make sense.

              we can use connect() to connect 2 signals right?

              raven-worxR 1 Reply Last reply
              0
              • saitejS saitej

                @raven-worx

                I am not editing the data, it is only displaying data from a source. So connecting datachanged signal to a slot does not make sense.

                we can use connect() to connect 2 signals right?

                raven-worxR Offline
                raven-worxR Offline
                raven-worx
                Moderators
                wrote on last edited by
                #17

                @saitej said in Dynamic Upadate of data to a ListModel:

                So connecting datachanged signal to a slot does not make sense.

                sorry but that doesn't make sense. I think you still don't understand the concept.
                It doesn't matter if you edit the data or not.

                The dataChanged() signal notifies the receiver (-> slot) that the data of the given index(es) has changed, and the data needs to be retrieved from the model again.

                --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
                If you have a question please use the forum so others can benefit from the solution in the future

                saitejS 1 Reply Last reply
                0
                • raven-worxR raven-worx

                  @saitej said in Dynamic Upadate of data to a ListModel:

                  So connecting datachanged signal to a slot does not make sense.

                  sorry but that doesn't make sense. I think you still don't understand the concept.
                  It doesn't matter if you edit the data or not.

                  The dataChanged() signal notifies the receiver (-> slot) that the data of the given index(es) has changed, and the data needs to be retrieved from the model again.

                  saitejS Offline
                  saitejS Offline
                  saitej
                  wrote on last edited by
                  #18

                  @raven-worx

                  I got what datachanged signal does. I would like to explain my problem better. Sorry for the inconvenience.

                  For ex:
                  I have a signal initialPolygonAreaChanged(qreal) emitted when ever initialPolygonArea is changed . I know the index of initialPolygonArea in the model. I need to connect the initialPolygonAreaChanged(qreal) with datachanged() signal. Is this the right way?

                  raven-worxR 1 Reply Last reply
                  0
                  • saitejS saitej

                    @raven-worx

                    I got what datachanged signal does. I would like to explain my problem better. Sorry for the inconvenience.

                    For ex:
                    I have a signal initialPolygonAreaChanged(qreal) emitted when ever initialPolygonArea is changed . I know the index of initialPolygonArea in the model. I need to connect the initialPolygonAreaChanged(qreal) with datachanged() signal. Is this the right way?

                    raven-worxR Offline
                    raven-worxR Offline
                    raven-worx
                    Moderators
                    wrote on last edited by raven-worx
                    #19

                    @saitej said in Dynamic Upadate of data to a ListModel:

                    Is this the right way?

                    so far so good. You can also emit the dataChanged() signal whenever you emit initialPolygonAreaChanged(), since you know the index. (If the initialPolygonAreaChanged() signal is defined in the model)

                    --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
                    If you have a question please use the forum so others can benefit from the solution in the future

                    saitejS 1 Reply Last reply
                    0
                    • raven-worxR raven-worx

                      @saitej said in Dynamic Upadate of data to a ListModel:

                      Is this the right way?

                      so far so good. You can also emit the dataChanged() signal whenever you emit initialPolygonAreaChanged(), since you know the index. (If the initialPolygonAreaChanged() signal is defined in the model)

                      saitejS Offline
                      saitejS Offline
                      saitej
                      wrote on last edited by
                      #20

                      @raven-worx

                      It is not defined in the model so I was to trying to connect via this:

                      connect(&av1,SIGNAL(initialPolygonAreaChanged(qreal)),&model,SIGNAL(dataChanged(model.index(i),model.index(i))));

                      What should this be changed to?

                      raven-worxR 1 Reply Last reply
                      0
                      • saitejS saitej

                        @raven-worx

                        It is not defined in the model so I was to trying to connect via this:

                        connect(&av1,SIGNAL(initialPolygonAreaChanged(qreal)),&model,SIGNAL(dataChanged(model.index(i),model.index(i))));

                        What should this be changed to?

                        raven-worxR Offline
                        raven-worxR Offline
                        raven-worx
                        Moderators
                        wrote on last edited by
                        #21

                        @saitej said in Dynamic Upadate of data to a ListModel:

                        connect(&av1,SIGNAL(initialPolygonAreaChanged(qreal)),&model,SIGNAL(dataChanged(model.index(i),model.index(i))));

                        This is not a valid connect statement. You are not allowed/supposed to do do a connection with the values already specified.

                        You will have to do something like this:

                        connect(&av1,SIGNAL(initialPolygonAreaChanged(qreal)),&model,SIGNAL(onInitialPolygonAreaChanged(qreal));
                        

                        In your model's onInitialPolygonAreaChanged(qreal) slot you then emit the dataChanged() signal with the correct indexes.

                        --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
                        If you have a question please use the forum so others can benefit from the solution in the future

                        saitejS 2 Replies Last reply
                        0
                        • raven-worxR raven-worx

                          @saitej said in Dynamic Upadate of data to a ListModel:

                          connect(&av1,SIGNAL(initialPolygonAreaChanged(qreal)),&model,SIGNAL(dataChanged(model.index(i),model.index(i))));

                          This is not a valid connect statement. You are not allowed/supposed to do do a connection with the values already specified.

                          You will have to do something like this:

                          connect(&av1,SIGNAL(initialPolygonAreaChanged(qreal)),&model,SIGNAL(onInitialPolygonAreaChanged(qreal));
                          

                          In your model's onInitialPolygonAreaChanged(qreal) slot you then emit the dataChanged() signal with the correct indexes.

                          saitejS Offline
                          saitejS Offline
                          saitej
                          wrote on last edited by
                          #22

                          @raven-worx

                          Oh .. !! I had thought of this but since there were lot of variables I was trying for a different way. I will go ahead this way.
                          Thanks!!

                          1 Reply Last reply
                          0
                          • raven-worxR raven-worx

                            @saitej said in Dynamic Upadate of data to a ListModel:

                            connect(&av1,SIGNAL(initialPolygonAreaChanged(qreal)),&model,SIGNAL(dataChanged(model.index(i),model.index(i))));

                            This is not a valid connect statement. You are not allowed/supposed to do do a connection with the values already specified.

                            You will have to do something like this:

                            connect(&av1,SIGNAL(initialPolygonAreaChanged(qreal)),&model,SIGNAL(onInitialPolygonAreaChanged(qreal));
                            

                            In your model's onInitialPolygonAreaChanged(qreal) slot you then emit the dataChanged() signal with the correct indexes.

                            saitejS Offline
                            saitejS Offline
                            saitej
                            wrote on last edited by
                            #23

                            @raven-worx

                            Mine is a list with a single column with three roles. I need to update only the value role , as suggested I am, emitting datachanged signal via

                            void DataModel::onInitialPolygonAreaChanged(qreal ){
                                //0 is the index of IPA
                                qDebug() << "IPA from model" ;
                               QVector<int> roleVector(ValueRole);
                            
                                emit dataChanged(index(0),index(0),roleVector);
                            }
                            

                            This also does not update the model.

                            raven-worxR 1 Reply Last reply
                            0
                            • saitejS saitej

                              @raven-worx

                              Mine is a list with a single column with three roles. I need to update only the value role , as suggested I am, emitting datachanged signal via

                              void DataModel::onInitialPolygonAreaChanged(qreal ){
                                  //0 is the index of IPA
                                  qDebug() << "IPA from model" ;
                                 QVector<int> roleVector(ValueRole);
                              
                                  emit dataChanged(index(0),index(0),roleVector);
                              }
                              

                              This also does not update the model.

                              raven-worxR Offline
                              raven-worxR Offline
                              raven-worx
                              Moderators
                              wrote on last edited by
                              #24

                              @saitej said in Dynamic Upadate of data to a ListModel:

                              This also does not update the model.

                              what do you mean?
                              The dataChanged() signal just informs (the view) about the change. So you need to trigger this signal after the data for this role has changed.
                              Who exactly is using the ValueRole?

                              Please show the code of your model.

                              --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
                              If you have a question please use the forum so others can benefit from the solution in the future

                              saitejS 1 Reply Last reply
                              0
                              • raven-worxR raven-worx

                                @saitej said in Dynamic Upadate of data to a ListModel:

                                This also does not update the model.

                                what do you mean?
                                The dataChanged() signal just informs (the view) about the change. So you need to trigger this signal after the data for this role has changed.
                                Who exactly is using the ValueRole?

                                Please show the code of your model.

                                saitejS Offline
                                saitejS Offline
                                saitej
                                wrote on last edited by saitej
                                #25

                                @raven-worx

                                I have triggered it exactly when my data is being changed.

                                My model:

                                class DataList{
                                public:
                                    DataList(const QString &name, const QString &value, const QString &category);
                                
                                    QString name() const;
                                    QString value() const;
                                    QString category() const;
                                
                                private:
                                    QString m_name;
                                    QString m_value;
                                    QString m_category;
                                };
                                
                                class DataModel : public QAbstractListModel
                                {
                                    Q_OBJECT
                                public:
                                    enum Roles {
                                        NameRole = Qt::UserRole + 1,
                                        ValueRole,
                                        CategoryRole
                                    };
                                
                                    DataModel(QAbstractItemModel *parent = 0);
                                    virtual ~DataModel() {}
                                    void addData(const DataList &datalist);
                                    int rowCount(const QModelIndex & parent = QModelIndex()) const;
                                
                                    QVariant data(const QModelIndex & index, int role=NameRole) const;
                                protected:
                                    QHash<int, QByteArray> roleNames() const;
                                
                                private:
                                    QList<DataList> m_datalist;
                                
                                public slots:
                                    void onInitialPolygonAreaChanged(qreal);
                                
                                
                                };
                                
                                
                                raven-worxR 1 Reply Last reply
                                0
                                • saitejS saitej

                                  @raven-worx

                                  I have triggered it exactly when my data is being changed.

                                  My model:

                                  class DataList{
                                  public:
                                      DataList(const QString &name, const QString &value, const QString &category);
                                  
                                      QString name() const;
                                      QString value() const;
                                      QString category() const;
                                  
                                  private:
                                      QString m_name;
                                      QString m_value;
                                      QString m_category;
                                  };
                                  
                                  class DataModel : public QAbstractListModel
                                  {
                                      Q_OBJECT
                                  public:
                                      enum Roles {
                                          NameRole = Qt::UserRole + 1,
                                          ValueRole,
                                          CategoryRole
                                      };
                                  
                                      DataModel(QAbstractItemModel *parent = 0);
                                      virtual ~DataModel() {}
                                      void addData(const DataList &datalist);
                                      int rowCount(const QModelIndex & parent = QModelIndex()) const;
                                  
                                      QVariant data(const QModelIndex & index, int role=NameRole) const;
                                  protected:
                                      QHash<int, QByteArray> roleNames() const;
                                  
                                  private:
                                      QList<DataList> m_datalist;
                                  
                                  public slots:
                                      void onInitialPolygonAreaChanged(qreal);
                                  
                                  
                                  };
                                  
                                  
                                  raven-worxR Offline
                                  raven-worxR Offline
                                  raven-worx
                                  Moderators
                                  wrote on last edited by
                                  #26

                                  @saitej said in Dynamic Upadate of data to a ListModel:

                                  I have triggered it exactly when my data is being changed.

                                  but who reads the ValueRole?! The view doesn't, it uses the `Qt::DisplayRole' by default.

                                  Also posting the header file of your model implementation is almost as good as providing nothing ;)

                                  --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
                                  If you have a question please use the forum so others can benefit from the solution in the future

                                  saitejS 1 Reply Last reply
                                  0
                                  • raven-worxR raven-worx

                                    @saitej said in Dynamic Upadate of data to a ListModel:

                                    I have triggered it exactly when my data is being changed.

                                    but who reads the ValueRole?! The view doesn't, it uses the `Qt::DisplayRole' by default.

                                    Also posting the header file of your model implementation is almost as good as providing nothing ;)

                                    saitejS Offline
                                    saitejS Offline
                                    saitej
                                    wrote on last edited by saitej
                                    #27

                                    @raven-worx

                                    
                                    DataList::DataList(const QString &name, const QString &value, const QString &category){
                                        m_name = name;
                                        m_value = value;
                                        m_category = category;
                                    
                                    }
                                    
                                    QString DataList::name() const{
                                        return m_name;
                                    
                                    }
                                    
                                    QString DataList::value() const{
                                        return m_value;
                                    }
                                    
                                    QString DataList::category() const{
                                        return m_category;
                                    }
                                    
                                    
                                    DataModel::DataModel(QAbstractItemModel *parent) :
                                        QAbstractListModel(parent)
                                    {
                                    
                                    }
                                    
                                    void DataModel::addData(const DataList &datalist){
                                        beginInsertRows(QModelIndex(), rowCount(), rowCount());
                                        m_datalist << datalist;
                                    
                                    
                                    }
                                    
                                    int DataModel::rowCount(const QModelIndex &parent) const{
                                        Q_UNUSED(parent);
                                        return m_datalist.count();
                                    }
                                    
                                    QVariant DataModel::data(const QModelIndex &index, int role) const{
                                        if (index.row() < 0 || index.row() >= m_datalist.count())
                                                return QVariant();
                                        const DataList &datalist = m_datalist[index.row()];
                                    
                                        if(role ==NameRole )
                                            return datalist.name();
                                        else if(role == ValueRole)
                                            return datalist.value();
                                        else if(role == CategoryRole)
                                            return datalist.category();
                                    
                                        return QVariant();
                                    }
                                    
                                    QHash<int, QByteArray> DataModel::roleNames() const {
                                        QHash<int, QByteArray> roles;
                                        roles[NameRole] = "name";
                                        roles[ValueRole] = "value";
                                        roles[CategoryRole] = "category";
                                        return roles;
                                    }
                                    
                                    void DataModel::onInitialPolygonAreaChanged(qreal ){
                                        //0 is the index of iPA
                                        qDebug() << "IPA from model" ;
                                       QVector<int> roleVector(ValueRole);
                                    
                                        emit dataChanged(index(0),index(0),roleVector);
                                    }
                                    
                                    
                                    raven-worxR 1 Reply Last reply
                                    0
                                    • saitejS saitej

                                      @raven-worx

                                      
                                      DataList::DataList(const QString &name, const QString &value, const QString &category){
                                          m_name = name;
                                          m_value = value;
                                          m_category = category;
                                      
                                      }
                                      
                                      QString DataList::name() const{
                                          return m_name;
                                      
                                      }
                                      
                                      QString DataList::value() const{
                                          return m_value;
                                      }
                                      
                                      QString DataList::category() const{
                                          return m_category;
                                      }
                                      
                                      
                                      DataModel::DataModel(QAbstractItemModel *parent) :
                                          QAbstractListModel(parent)
                                      {
                                      
                                      }
                                      
                                      void DataModel::addData(const DataList &datalist){
                                          beginInsertRows(QModelIndex(), rowCount(), rowCount());
                                          m_datalist << datalist;
                                      
                                      
                                      }
                                      
                                      int DataModel::rowCount(const QModelIndex &parent) const{
                                          Q_UNUSED(parent);
                                          return m_datalist.count();
                                      }
                                      
                                      QVariant DataModel::data(const QModelIndex &index, int role) const{
                                          if (index.row() < 0 || index.row() >= m_datalist.count())
                                                  return QVariant();
                                          const DataList &datalist = m_datalist[index.row()];
                                      
                                          if(role ==NameRole )
                                              return datalist.name();
                                          else if(role == ValueRole)
                                              return datalist.value();
                                          else if(role == CategoryRole)
                                              return datalist.category();
                                      
                                          return QVariant();
                                      }
                                      
                                      QHash<int, QByteArray> DataModel::roleNames() const {
                                          QHash<int, QByteArray> roles;
                                          roles[NameRole] = "name";
                                          roles[ValueRole] = "value";
                                          roles[CategoryRole] = "category";
                                          return roles;
                                      }
                                      
                                      void DataModel::onInitialPolygonAreaChanged(qreal ){
                                          //0 is the index of iPA
                                          qDebug() << "IPA from model" ;
                                         QVector<int> roleVector(ValueRole);
                                      
                                          emit dataChanged(index(0),index(0),roleVector);
                                      }
                                      
                                      
                                      raven-worxR Offline
                                      raven-worxR Offline
                                      raven-worx
                                      Moderators
                                      wrote on last edited by
                                      #28

                                      @saitej

                                      1. DataModel constructor: not an issue, but i guess it's not necessary to require a QAbstractItemModel type as parent. I would change it to QObject
                                      2. you are not calling endInserteRows() in DataModel::addData() after you've appended the data.
                                      3. I ask one last time, since you are also not returning a DisplayRole value. How is your view using the ValueRole

                                      I don't see where the call to onInitialPolygonAreaChanged() comes from, and where the data update before this call happens.
                                      If you call addData() before triggering the onInitialPolygonAreaChanged() slot, all you need is to add the endInsertRows() call. If thats the case you also DO NOT need to make sure dataChanged() is triggered, because as i also already said, this is only necessary for EXISTING data changes. The updating on inserts is already handled by the beginInsertRows()/endInsertRows() calls.

                                      --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
                                      If you have a question please use the forum so others can benefit from the solution in the future

                                      saitejS 2 Replies Last reply
                                      0
                                      • raven-worxR raven-worx

                                        @saitej

                                        1. DataModel constructor: not an issue, but i guess it's not necessary to require a QAbstractItemModel type as parent. I would change it to QObject
                                        2. you are not calling endInserteRows() in DataModel::addData() after you've appended the data.
                                        3. I ask one last time, since you are also not returning a DisplayRole value. How is your view using the ValueRole

                                        I don't see where the call to onInitialPolygonAreaChanged() comes from, and where the data update before this call happens.
                                        If you call addData() before triggering the onInitialPolygonAreaChanged() slot, all you need is to add the endInsertRows() call. If thats the case you also DO NOT need to make sure dataChanged() is triggered, because as i also already said, this is only necessary for EXISTING data changes. The updating on inserts is already handled by the beginInsertRows()/endInsertRows() calls.

                                        saitejS Offline
                                        saitejS Offline
                                        saitej
                                        wrote on last edited by
                                        #29

                                        @raven-worx

                                        I have initialized the model in the main window.h :

                                        DataModel model;
                                        

                                        In the mainwindow.cpp file

                                         model.addData(DataList(QString("Initial Polygon Area"),QString::number(uav1.initialPolygonArea()) + " sq.km",QString("Area")));
                                            connect(&uav1,SIGNAL(initialPolygonAreaChanged(qreal)),&model,SLOT(onInitialPolygonAreaChanged(qreal)));
                                        

                                        This is how I am calling onInitialPolygonAreaChanged slot.

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                                        • raven-worxR raven-worx

                                          @saitej

                                          1. DataModel constructor: not an issue, but i guess it's not necessary to require a QAbstractItemModel type as parent. I would change it to QObject
                                          2. you are not calling endInserteRows() in DataModel::addData() after you've appended the data.
                                          3. I ask one last time, since you are also not returning a DisplayRole value. How is your view using the ValueRole

                                          I don't see where the call to onInitialPolygonAreaChanged() comes from, and where the data update before this call happens.
                                          If you call addData() before triggering the onInitialPolygonAreaChanged() slot, all you need is to add the endInsertRows() call. If thats the case you also DO NOT need to make sure dataChanged() is triggered, because as i also already said, this is only necessary for EXISTING data changes. The updating on inserts is already handled by the beginInsertRows()/endInsertRows() calls.

                                          saitejS Offline
                                          saitejS Offline
                                          saitej
                                          wrote on last edited by
                                          #30

                                          @raven-worx said in Dynamic Upadate of data to a ListModel:

                                          I ask one last time, since you are also not returning a DisplayRole value. How is your view using the ValueRole

                                          Where should I return DisplayRole and why ?

                                          This is how I am using in the view:

                                          qml file:

                                           ListView {
                                                      id: view
                                                      anchors.top: parent.top
                                                      anchors.bottom: parent.bottom
                                          
                                                      width: parent.width
                                                      model: UAVModel
                                                      delegate: Text { text: name + "     " + value; font.pixelSize: 18 ; color: "white"}
                                          
                                                      section.property: "category"
                                                      section.criteria: ViewSection.FullString
                                                      section.delegate: sectionHeading
                                                  }
                                          
                                          raven-worxR 1 Reply Last reply
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