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QAbstractTableModel + QML TableView: How to call setData?

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  • VRoninV VRonin

    From https://wiki.qt.io/How_to_Use_a_Custom_Class_in_C%2B%2B_Model_and_QML_View

    accessing our data is very easy we just use the roleName.propertyName syntax. Since we saved our data in Qt::EditRole we used edit as role name (a list of the default role names is In QAbstractItemModel's documentation)

    basically edit is the name of the role as returned by QAbstractItemModel::roleNames(). The example doesn't overload it so the default name coresponding to Qt::EditRole is used

    B Offline
    B Offline
    Bremenpl
    wrote on last edited by Bremenpl
    #7

    @VRonin Thanks for clarification, this gets complicated. My override looks as follows:

    /**
     * @brief	Obtains the role names needed on the QML side.
     * @return	A hash of role names.
     */
    QHash<int, QByteArray> CVarTableModel::roleNames() const
    {
    	QHash<int, QByteArray> roles;
    	const int colCount = columnCount();
    
    	for (int col = 0; col < colCount; col++)
    		roles[Qt::UserRole + col] = role(col).toByteArray();
    
    	return roles;
    }
    

    And the role method is:

    /**
     * @brief	Obtains the role name string assiociated to the provided \p column
     * @param	column: Column number/ index.
     * @return	Role name string (as Qvariant) in case \p column is valid.
     */
    QVariant CVarTableModel::role(const int column) const
    {
    	if (!isColumnValid(column))
    		return QString();
    
    	return QVariant::fromValue(static_cast<Columns>(column));
    }
    

    Columns is a simple enum:

    	/**
    	 * @brief	An enumeration class providing the columns and the amount of
    	 *			columns as well (use ZCOUNT as always last member).
    	 */
    	enum class Columns
    	{
    		Name = 0,
    		Unit,
    		Value,
    
    		ZCOUNT,
    	};
    	Q_ENUM(Columns)
    

    So my role names would be Name, Unit and Value. How would this be consistent with the edit way if its custom?
    I would appreciate further help.

    lprzenioslo.zut.edu.pl

    VRoninV 1 Reply Last reply
    0
    • B Bremenpl

      @VRonin Thanks for clarification, this gets complicated. My override looks as follows:

      /**
       * @brief	Obtains the role names needed on the QML side.
       * @return	A hash of role names.
       */
      QHash<int, QByteArray> CVarTableModel::roleNames() const
      {
      	QHash<int, QByteArray> roles;
      	const int colCount = columnCount();
      
      	for (int col = 0; col < colCount; col++)
      		roles[Qt::UserRole + col] = role(col).toByteArray();
      
      	return roles;
      }
      

      And the role method is:

      /**
       * @brief	Obtains the role name string assiociated to the provided \p column
       * @param	column: Column number/ index.
       * @return	Role name string (as Qvariant) in case \p column is valid.
       */
      QVariant CVarTableModel::role(const int column) const
      {
      	if (!isColumnValid(column))
      		return QString();
      
      	return QVariant::fromValue(static_cast<Columns>(column));
      }
      

      Columns is a simple enum:

      	/**
      	 * @brief	An enumeration class providing the columns and the amount of
      	 *			columns as well (use ZCOUNT as always last member).
      	 */
      	enum class Columns
      	{
      		Name = 0,
      		Unit,
      		Value,
      
      		ZCOUNT,
      	};
      	Q_ENUM(Columns)
      

      So my role names would be Name, Unit and Value. How would this be consistent with the edit way if its custom?
      I would appreciate further help.

      VRoninV Offline
      VRoninV Offline
      VRonin
      wrote on last edited by
      #8

      So my role names would be Name, Unit and Value. How would this be consistent with the edit way if its custom?

      easy, replace edit with Name, Unit or Value. For example, if the Name role will contain a QString you can use:

      delegate: TextInput  {
                      text: Name
                      onEditingFinished: {
                          Name = text
                      }
                  }
      

      My override looks as follows:

      This is a very convoluted way to go about it. You can just use QMetaEnum::fromType<Derived::Columns>().valueToKeys(col);

      for (int col = 0; col < colCount; col++)

      Looks like columns and roles are the same thing here but since 1 year ago they are now 2 distinct things (as they are in QtWidgets): https://blog.qt.io/blog/2018/08/29/tableview/

      "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

      B 1 Reply Last reply
      0
      • VRoninV VRonin

        So my role names would be Name, Unit and Value. How would this be consistent with the edit way if its custom?

        easy, replace edit with Name, Unit or Value. For example, if the Name role will contain a QString you can use:

        delegate: TextInput  {
                        text: Name
                        onEditingFinished: {
                            Name = text
                        }
                    }
        

        My override looks as follows:

        This is a very convoluted way to go about it. You can just use QMetaEnum::fromType<Derived::Columns>().valueToKeys(col);

        for (int col = 0; col < colCount; col++)

        Looks like columns and roles are the same thing here but since 1 year ago they are now 2 distinct things (as they are in QtWidgets): https://blog.qt.io/blog/2018/08/29/tableview/

        B Offline
        B Offline
        Bremenpl
        wrote on last edited by
        #9

        @VRonin Thank you for follow-up. As for the method optimization, I will get back to that. But for the main problem, I did:

        Component
        {
        	id: theInputComp;
        
        	TextInput
        	{
        		id: textInputId;
        		anchors.fill: parent;
        
        		onEditingFinished:
        		{
        			theLoader.visible = false;
        			theCellText.visible = true;
        			//tableModel.setData(styleData.row,
        							   //styleData.column, text);
        			Name = text;
        		}
        	}
        }
        

        And received: qrc:/UBasicTable.qml:109: Error: Invalid write to global property "Name"
        Am I missing something?

        lprzenioslo.zut.edu.pl

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        • VRoninV Offline
          VRoninV Offline
          VRonin
          wrote on last edited by
          #10

          Name might be a reserved word. Try changing Name = 0, to colName = 0, and use text: colName and colName = text

          "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

          B 1 Reply Last reply
          0
          • VRoninV VRonin

            Name might be a reserved word. Try changing Name = 0, to colName = 0, and use text: colName and colName = text

            B Offline
            B Offline
            Bremenpl
            wrote on last edited by
            #11

            @VRonin Doesnt matter how I call it:

            qrc:/UBasicTable.qml:109: Error: Invalid write to global property "colName"
            qrc:/UBasicTable.qml:109: Error: Invalid write to global property "colName1" // this doesnt exist
            

            Any other hints :/?

            lprzenioslo.zut.edu.pl

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            0
            • B Offline
              B Offline
              Bremenpl
              wrote on last edited by
              #12

              Just BTW... Figured out why doesnt the dataChanged signal fire the table update. I was calling it like this:

              emit dataChanged(index, index, {role});
              

              and role was always Qt::EditRole. Now I call it without roles parameter:

              emit dataChanged(index, index);
              

              And the TableView cells are being updated! Thanks for the help @VRonin, it led me to the right place for this one.
              I still havent figured out how to automatically call setData from the QML though (using the presented workaround). If you have any more ideas please let me know.

              lprzenioslo.zut.edu.pl

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              • VRoninV Offline
                VRoninV Offline
                VRonin
                wrote on last edited by VRonin
                #13

                Are you sure you are inside delegate:?
                This is a minimal working example:

                #include <QGuiApplication>
                #include <QQmlContext>
                #include <QQmlApplicationEngine>
                #include <QStringListModel>
                #include <QDebug>
                class MyModel : public QStringListModel{
                public:
                    MyModel(QObject *parent = nullptr) : QStringListModel(parent)
                    {}
                    QHash<int, QByteArray> roleNames() const override
                    {
                        QHash<int, QByteArray> roles;
                
                            roles[Qt::EditRole] = QByteArrayLiteral("TestRole");
                            roles[Qt::DisplayRole] = QByteArrayLiteral("AnotherRole");
                
                        return roles;
                    }
                };
                
                int main(int argc, char *argv[])
                {
                #if defined(Q_OS_WIN)
                    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
                #endif
                    QGuiApplication app(argc, argv);
                    QQmlApplicationEngine engine;
                    MyModel model;
                    QObject::connect(&model,&MyModel::dataChanged,[](const QModelIndex& idx){
                        qDebug() << "Changed: " << idx.row() << " " << idx.data().toString();
                    });
                    model.setStringList(QStringList{"aaa","bbb","ccc"});
                    engine.rootContext()->setContextProperty("mymodel", &model);
                    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
                    if (engine.rootObjects().isEmpty())
                        return -1;
                    return app.exec();
                }
                
                import QtQml 2.2
                import QtQuick 2.7
                import QtQuick.Window 2.2
                import QtQuick.Controls 2.3
                
                Window {
                    visible: true
                    width: 640
                    height: 480
                    title: qsTr("Test Edit")
                
                        ListView {
                            anchors.fill: parent;
                            width: 200; height: 250
                            model: mymodel
                            delegate: TextInput  {
                                text: TestRole
                                onEditingFinished: {
                                    TestRole = text
                                }
                            }
                        }
                }
                

                "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

                B 1 Reply Last reply
                1
                • VRoninV VRonin

                  Are you sure you are inside delegate:?
                  This is a minimal working example:

                  #include <QGuiApplication>
                  #include <QQmlContext>
                  #include <QQmlApplicationEngine>
                  #include <QStringListModel>
                  #include <QDebug>
                  class MyModel : public QStringListModel{
                  public:
                      MyModel(QObject *parent = nullptr) : QStringListModel(parent)
                      {}
                      QHash<int, QByteArray> roleNames() const override
                      {
                          QHash<int, QByteArray> roles;
                  
                              roles[Qt::EditRole] = QByteArrayLiteral("TestRole");
                              roles[Qt::DisplayRole] = QByteArrayLiteral("AnotherRole");
                  
                          return roles;
                      }
                  };
                  
                  int main(int argc, char *argv[])
                  {
                  #if defined(Q_OS_WIN)
                      QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
                  #endif
                      QGuiApplication app(argc, argv);
                      QQmlApplicationEngine engine;
                      MyModel model;
                      QObject::connect(&model,&MyModel::dataChanged,[](const QModelIndex& idx){
                          qDebug() << "Changed: " << idx.row() << " " << idx.data().toString();
                      });
                      model.setStringList(QStringList{"aaa","bbb","ccc"});
                      engine.rootContext()->setContextProperty("mymodel", &model);
                      engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
                      if (engine.rootObjects().isEmpty())
                          return -1;
                      return app.exec();
                  }
                  
                  import QtQml 2.2
                  import QtQuick 2.7
                  import QtQuick.Window 2.2
                  import QtQuick.Controls 2.3
                  
                  Window {
                      visible: true
                      width: 640
                      height: 480
                      title: qsTr("Test Edit")
                  
                          ListView {
                              anchors.fill: parent;
                              width: 200; height: 250
                              model: mymodel
                              delegate: TextInput  {
                                  text: TestRole
                                  onEditingFinished: {
                                      TestRole = text
                                  }
                              }
                          }
                  }
                  
                  B Offline
                  B Offline
                  Bremenpl
                  wrote on last edited by Bremenpl
                  #14

                  @VRonin Hmmm... Here is the thing- I am inside itemDelegate not delegate. delegate is available in different QtQuick.Controls version. If I switch to it, I will no longer have my other components available, ie Popup. Isnt itemDelegate and delegate the same thing?

                  Look at the docs, TableView has no delegate member: https://doc.qt.io/qt-5/qml-qtquick-controls-tableview.html#rowDelegate-prop

                  lprzenioslo.zut.edu.pl

                  1 Reply Last reply
                  0
                  • VRoninV Offline
                    VRoninV Offline
                    VRonin
                    wrote on last edited by VRonin
                    #15

                    Looks like you are still using Qt Quick controls 1.
                    Qt Quick controls 2 is already 3 years old.

                    If I switch to it, I will no longer have my other components available, ie Popup

                    Qt Quick Controls 2 has https://doc.qt.io/qt-5/qml-qtquick-controls2-popup.html

                    "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

                    B 1 Reply Last reply
                    1
                    • VRoninV VRonin

                      Looks like you are still using Qt Quick controls 1.
                      Qt Quick controls 2 is already 3 years old.

                      If I switch to it, I will no longer have my other components available, ie Popup

                      Qt Quick Controls 2 has https://doc.qt.io/qt-5/qml-qtquick-controls2-popup.html

                      B Offline
                      B Offline
                      Bremenpl
                      wrote on last edited by
                      #16

                      @VRonin QtQuick.Controls 2.5 do have delegate but dont have TableViewColumn which I am using for columns setting. Is there a better way now?

                      lprzenioslo.zut.edu.pl

                      VRoninV 1 Reply Last reply
                      0
                      • B Bremenpl

                        @VRonin QtQuick.Controls 2.5 do have delegate but dont have TableViewColumn which I am using for columns setting. Is there a better way now?

                        VRoninV Offline
                        VRoninV Offline
                        VRonin
                        wrote on last edited by
                        #17

                        @Bremenpl said in QAbstractTableModel + QML TableView: How to call setData?:

                        Is there a better way now?

                        @VRonin said in QAbstractTableModel + QML TableView: How to call setData?:

                        Looks like columns and roles are the same thing here but since 1 year ago they are now 2 distinct things (as they are in QtWidgets): https://blog.qt.io/blog/2018/08/29/tableview/

                        "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

                        B 1 Reply Last reply
                        1
                        • VRoninV VRonin

                          @Bremenpl said in QAbstractTableModel + QML TableView: How to call setData?:

                          Is there a better way now?

                          @VRonin said in QAbstractTableModel + QML TableView: How to call setData?:

                          Looks like columns and roles are the same thing here but since 1 year ago they are now 2 distinct things (as they are in QtWidgets): https://blog.qt.io/blog/2018/08/29/tableview/

                          B Offline
                          B Offline
                          Bremenpl
                          wrote on last edited by
                          #18

                          @VRonin Ok... So now everything I got ahead of with styleData is no longer working. This time I am really confused. Those links threat about animations the most and what I need for now is to be able to send/ receive data from the C++ model. Is there any example for that?

                          lprzenioslo.zut.edu.pl

                          VRoninV 1 Reply Last reply
                          0
                          • B Bremenpl

                            @VRonin Ok... So now everything I got ahead of with styleData is no longer working. This time I am really confused. Those links threat about animations the most and what I need for now is to be able to send/ receive data from the C++ model. Is there any example for that?

                            VRoninV Offline
                            VRoninV Offline
                            VRonin
                            wrote on last edited by
                            #19

                            @Bremenpl said in QAbstractTableModel + QML TableView: How to call setData?:

                            So now everything I got ahead of with styleData is no longer working.

                            What is styleData?

                            "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

                            B 1 Reply Last reply
                            1
                            • VRoninV VRonin

                              @Bremenpl said in QAbstractTableModel + QML TableView: How to call setData?:

                              So now everything I got ahead of with styleData is no longer working.

                              What is styleData?

                              B Offline
                              B Offline
                              Bremenpl
                              wrote on last edited by Bremenpl
                              #20

                              @VRonin It was available in itemDelegate: https://doc.qt.io/qt-5/qml-qtquick-controls-tableview.html#itemDelegate-prop
                              One could use it to locate itself in the table as well as read model data.

                              lprzenioslo.zut.edu.pl

                              VRoninV 1 Reply Last reply
                              0
                              • B Bremenpl

                                @VRonin It was available in itemDelegate: https://doc.qt.io/qt-5/qml-qtquick-controls-tableview.html#itemDelegate-prop
                                One could use it to locate itself in the table as well as read model data.

                                VRoninV Offline
                                VRoninV Offline
                                VRonin
                                wrote on last edited by
                                #21

                                @Bremenpl said in QAbstractTableModel + QML TableView: How to call setData?:

                                One could use it to locate itself in the table as well as read model data.

                                now you don't need it anymore. you just access role names directly to read data and you can use index, row and column directly to locate yourself within the model

                                Btw, this doesnt call setData:

                                Yes it does. If the dataChanged signal is not enough to convince you you can add the below to MyModel

                                bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) override{
                                        qDebug() << "Called setData";
                                        return QStringListModel::setData(index,value,role);
                                    }
                                

                                "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

                                B 1 Reply Last reply
                                1
                                • VRoninV VRonin

                                  @Bremenpl said in QAbstractTableModel + QML TableView: How to call setData?:

                                  One could use it to locate itself in the table as well as read model data.

                                  now you don't need it anymore. you just access role names directly to read data and you can use index, row and column directly to locate yourself within the model

                                  Btw, this doesnt call setData:

                                  Yes it does. If the dataChanged signal is not enough to convince you you can add the below to MyModel

                                  bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) override{
                                          qDebug() << "Called setData";
                                          return QStringListModel::setData(index,value,role);
                                      }
                                  
                                  B Offline
                                  B Offline
                                  Bremenpl
                                  wrote on last edited by
                                  #22

                                  @VRonin Ok, you are right! Thanks.
                                  It feels like we are really close this time. So this is the components now:

                                  		TableView
                                  		{
                                  			anchors.fill: parent;
                                  			model: tableModel;
                                  
                                  			delegate: TextInput
                                  			{
                                  				text: Name;
                                  
                                  				onEditingFinished:
                                  				{
                                  					Name = text
                                  				}
                                  			}
                                  		}
                                  

                                  My columns and roles are still mixed together because of the obsolete behavior- this needs to be disconnected. In this case, what should the roleNames override method return actually?

                                  lprzenioslo.zut.edu.pl

                                  1 Reply Last reply
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                                  • VRoninV Offline
                                    VRoninV Offline
                                    VRonin
                                    wrote on last edited by VRonin
                                    #23

                                    @Bremenpl said in QAbstractTableModel + QML TableView: How to call setData?:

                                    hat should the roleNames override method return actually?

                                    I would not override it at all and just use the default edit

                                    				text: edit
                                    
                                    				onEditingFinished:
                                    				{
                                    					edit = text
                                    				}
                                    

                                    "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

                                    B 1 Reply Last reply
                                    1
                                    • VRoninV VRonin

                                      @Bremenpl said in QAbstractTableModel + QML TableView: How to call setData?:

                                      hat should the roleNames override method return actually?

                                      I would not override it at all and just use the default edit

                                      				text: edit
                                      
                                      				onEditingFinished:
                                      				{
                                      					edit = text
                                      				}
                                      
                                      B Offline
                                      B Offline
                                      Bremenpl
                                      wrote on last edited by
                                      #24

                                      @VRonin , yeah I just came to realize that too. I did:

                                      delegate: TextInput
                                      			{
                                      				text: display;
                                      
                                      				onEditingFinished:
                                      				{
                                      					edit = text
                                      				}
                                      			}
                                      

                                      Which I believe in this context gives the same effect.
                                      Alright... Thank you very much for your feedback, you helped me a lot.
                                      Now I only need to figure out either headerData can be utilized and that would be it.

                                      lprzenioslo.zut.edu.pl

                                      VRoninV 1 Reply Last reply
                                      0
                                      • B Bremenpl

                                        @VRonin , yeah I just came to realize that too. I did:

                                        delegate: TextInput
                                        			{
                                        				text: display;
                                        
                                        				onEditingFinished:
                                        				{
                                        					edit = text
                                        				}
                                        			}
                                        

                                        Which I believe in this context gives the same effect.
                                        Alright... Thank you very much for your feedback, you helped me a lot.
                                        Now I only need to figure out either headerData can be utilized and that would be it.

                                        VRoninV Offline
                                        VRoninV Offline
                                        VRonin
                                        wrote on last edited by
                                        #25

                                        @Bremenpl said in QAbstractTableModel + QML TableView: How to call setData?:

                                        Now I only need to figure out either headerData can be utilized and that would be it.

                                        I'm afraid that part has not been developed by Qt yet

                                        We’re also working on a TableHeader, TableModel, as well as a DelegateChooser.

                                        "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

                                        B 1 Reply Last reply
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                                        • VRoninV VRonin

                                          @Bremenpl said in QAbstractTableModel + QML TableView: How to call setData?:

                                          Now I only need to figure out either headerData can be utilized and that would be it.

                                          I'm afraid that part has not been developed by Qt yet

                                          We’re also working on a TableHeader, TableModel, as well as a DelegateChooser.

                                          B Offline
                                          B Offline
                                          Bremenpl
                                          wrote on last edited by
                                          #26

                                          @VRonin So as for now, is there a way to set the column header at all?

                                          lprzenioslo.zut.edu.pl

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