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Use setData() from QML

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  • E Offline
    E Offline
    ed_robcont_
    wrote on last edited by
    #1

    Hi community,
    I reimplemented QAbstractListModel in order to display a list of my custom objects.
    C++ side works fine, but I have some problems using setData(), data() and others function directly from QML.
    What am I doing wrong? Below my relevant code.

    DataModel.cpp

    DataModel::DataModel(QObject *parent)
        : QAbstractListModel(parent)
    {
        for (int i = 1; i < 8; i++)
            mList.append({ i, 0, 0.0, 0, false });
    
        setData(index(3,0), true, PlottedRole);
    }
    
    Qt::ItemFlags DataModel::flags(const QModelIndex &index) const
    {
        if (!index.isValid())
            return Qt::NoItemFlags;
    
        return Qt::ItemIsEditable | Qt::ItemIsUserCheckable;
    }
    
    QVariant DataModel::data(const QModelIndex &index, int role) const
    {
        if (!index.isValid())
            return QVariant();
    
        if (index.row() >= mList.size())
            return QVariant();
    
        const DataItem item = mList.at(index.row());
    
        switch (role)
        {
        case ChannelRole:
            return QVariant(item.channel);
        case SensorRole:
            return QVariant(item.sensor);
        case TemperatureRole:
            return QVariant(item.temperature);
        case AlarmRole:
            return QVariant(item.alarm);
        case PlottedRole:
            return QVariant(item.plotted);
        default:
            return QVariant();
        }
    
        return QVariant();
    }
    
    bool DataModel::setData(const QModelIndex &index, const QVariant &value, int role)
    {
        if (data(index, role) != value)
        {
            DataItem item = mList.at(index.row());
    
            switch (role)
            {
            case ChannelRole:
                item.channel = value.toInt();
                break;
            case SensorRole:
                item.sensor = value.toInt();
                break;
            case TemperatureRole:
                item.temperature = value.toDouble();
                break;
            case AlarmRole:
                item.alarm = value.toInt();
                break;
            case PlottedRole:
                item.plotted = value.toBool();
                break;
            default:
                return false;
            }
    
            mList.replace(index.row(), item);
    
            emit dataChanged(index, index, QVector<int>() << role);
            return true;
        }
        return false;
    }
    
    int DataModel::rowCount(const QModelIndex &parent) const
    {
        if (parent.isValid())
            return 0;
    
        return mList.size();
    }
    
    bool DataModel::insertRows(int row, int count, const QModelIndex &parent)
    {
        if (row < 0 || row >= mList.size())
            return false;
    
        beginInsertRows(parent, row, row + count - 1);
    
        for (int i = 0; i < count; i++)
            mList.insert(row, { row, 0, 0.0, 0, false });
    
        endInsertRows();
    
        return true;
    }
    
    bool DataModel::removeRows(int row, int count, const QModelIndex &parent)
    {
        if (row < 0 || row >= mList.size() || count > mList.size())
            return false;
    
        beginRemoveRows(parent, row, row + count - 1);
    
        for (int i = 0; i < count; i++)
            mList.removeAt(row);
    
        endRemoveRows();
    
        return true;
    }
    
    QHash<int, QByteArray> DataModel::roleNames() const
    {
        QHash<int, QByteArray> roles;
        roles[ChannelRole] = "channel";
        roles[SensorRole] = "sensor";
        roles[TemperatureRole] = "temperature";
        roles[AlarmRole] = "alarm";
        roles[PlottedRole] = "plotted";
    
        return roles;
    }
    

    DataList.qml

    GroupBox {
        id: root
        title: qsTr("<b> CHANNEL DATA</b>")
        implicitWidth: 1180
        implicitHeight: 500
    
        ColumnLayout {
            anchors.fill: parent
    
            DataHeader {
                id: header
                Layout.fillWidth: true
    
                onHeaderPlotChecked: {
                    console.log(dmodel.index(3,1)); // THIS NOT WORK
                }
            }
    
            ListView {
                id: listView
                clip: true
                Layout.fillWidth: true
                Layout.fillHeight: true
    
                delegate: DataDelegate {
                    id: ddelegate
                    width: listView.width
                }
    
                model: DataModel {
                    id: dmodel
                }
    
                ScrollIndicator.vertical: ScrollIndicator {}
            }
        }
    }
    

    DataDelegate.qml

    ItemDelegate {
        id: root
    
        signal delegatePlotChecked(int row, bool checked)
    
        RowLayout {
            anchors.fill: parent
            spacing: 0
    
            Frame {
                Label {
                    text: channel
                    ...
                }
            }
    
            Frame {
                Label {
                    text: sensor
                    ...
                }
            }
    
            Frame {
                Label {
                    text: temperature
                    ...
                }
            }
    
            Frame {
                Label {
                    text: alarm
                    ...
                }
            }
    
            Frame {
                CheckBox {
                    checked: plotted
                    ...
                    onCheckStateChanged: root.delegatePlotChecked(index, checked)
                }
            }
        }
    }
    
    1 Reply Last reply
    0
    • sierdzioS Offline
      sierdzioS Offline
      sierdzio
      Moderators
      wrote on last edited by
      #2

      ... and your problem is? Your code looks OK. If the delegate does not see the data (since it's in another file), you can try model.channel instead of channel.

      (Z(:^

      E 1 Reply Last reply
      0
      • sierdzioS sierdzio

        ... and your problem is? Your code looks OK. If the delegate does not see the data (since it's in another file), you can try model.channel instead of channel.

        E Offline
        E Offline
        ed_robcont_
        wrote on last edited by ed_robcont_
        #3

        @sierdzio
        First of all, thanks for your quick response.
        The problem is that I don't know how to use setData, index, or others model-related functions from QML. When I try console.log(model.channel) I alwasy get undefined.

        My final goal is to check/uncheck all the delegates' checkboxes when the header checkbox has been checked. My idea was somethig similar

        onHeaderPlotChecked: {
            console.log("check all " + checked);
           
            for (var i = 0; i < model.rowCounts(); < i++) {
                var index = model.index(i, 1); // get row
                model.setData(index, checked, model.PlottedRole); // replace data
            }
        }
        
        1 Reply Last reply
        0
        • sierdzioS Offline
          sierdzioS Offline
          sierdzio
          Moderators
          wrote on last edited by
          #4

          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.

          (Z(:^

          E 1 Reply Last reply
          1
          • 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?

            1 Reply Last reply
            0
            • 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!
                1 Reply Last reply
                0
                • 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(:^

                  E 1 Reply Last reply
                  0
                  • 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
                      1
                      • 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)
                        }
                        
                        1 Reply Last reply
                        0
                        • 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(:^

                          E 1 Reply Last reply
                          0
                          • 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
                            E Offline
                            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*>
                            1 Reply Last reply
                            0
                            • 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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