Using pointer in C++ model for QML

[JorisC]

Dear All,

I'm currently coding a c++ model for display it in a ListVieew in QML side. This point is OK for me, I have followed the c++ model in QML tutorial (https://www.youtube.com/watch?v=9BcAYDlpuT8&list=WL&index=29&t=1280s)

Problem: Contrary to the turorial, in my C++ list class I have a structure which contains a pointer ( serie_graphe* serie;) and I don't know how to access it in QML side. In QML side, I would like to deal with something like "model.serie"

serielist.h

#ifndef SERIELIST_H
#define SERIELIST_H

#include <QObject>
#include <QVector>
#include <serie_graphe.h>

struct SerieItem
{
    bool selection;
    serie_graphe* serie;
    QString nom;
    int id;
};

class SerieList : public QObject
{
   Q_OBJECT
public:
    explicit SerieList(QObject *parent = nullptr);

    QVector<SerieItem> items() const;

    bool setItemAt(int index, const SerieItem &item);

signals:
    void preItemAppended();
    void postItemAppended();

public slots:
    void appendItem(serie_graphe* nouvelle_serie);

public:
    QVector<SerieItem> mItems;

    int numero = 0;
};

#endif // SERIELIST_H

serielist.cpp

#include "serielist.h"

SerieList::SerieList(QObject *parent) : QObject(parent)
{
//    mItems.append({ true, QStringLiteral("Nick ta reum")});
//    mItems.append({ false, QStringLiteral("Fix the sink") });
}

QVector<SerieItem> SerieList::items() const
{
    return mItems;
}

bool SerieList::setItemAt(int index, const SerieItem &item)
{
    if (index < 0 || index >= mItems.size())
        return false;

    const SerieItem &oldItem = mItems.at(index);
    if (item.selection == oldItem.selection && item.nom == oldItem.nom)
        return false;

    mItems[index] = item;
    return true;
}

void SerieList::appendItem(serie_graphe* nouvelle_serie)
{
    emit preItemAppended();

    SerieItem item;
    item.selection = false;
    item.serie = nouvelle_serie;
    item.nom = nouvelle_serie->nom_serie;
    item.id = numero;
    mItems.append(item);

    numero++;                           //On incrémente le numéro de série en vue d'un prochain ajout

    emit postItemAppended();
}

Unfortunately, in the data function in seriemodel.cpp, I cannot handle "serieRole" with a Qvariant in my model (seriemodel class) ...

seriemodel.cpp

#include "seriemodel.h"

#include "serielist.h"

SerieModel::SerieModel(QObject *parent)
    :QAbstractListModel(parent)
    , mList(nullptr)
{
}


int SerieModel::rowCount(const QModelIndex &parent) const
{
    if (parent.isValid() || !mList )
        return 0;

    return mList->items().size();
}


QVariant SerieModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid() || !mList)
        return QVariant();

    const SerieItem item = mList->items().at(index.row());
    switch (role) {
    case SelectionRole:
        return QVariant(item.selection);
    case NomRole:
        return QVariant(item.nom);
    case SerieRole:
        return QVariant(item.serie);            //PROBLEM HERE because item.serie is a pointer .... and cannot be handle with QVARIANT
    case IDRole:
        return QVariant(item.id);
    }

    return QVariant();
}


Qt::ItemFlags SerieModel::flags(const QModelIndex &index) const
{
    if (!index.isValid())
        return Qt::NoItemFlags;

    return Qt::ItemIsEditable; // FIXME: Implement me!
}

QHash<int, QByteArray> SerieModel::roleNames() const
{
    QHash<int, QByteArray> names;
    names[SelectionRole] = "selection";
    names[NomRole] = "nom";
    names[SerieRole] = "serie";
    names[IDRole] = "id";
    return names;
}

SerieList *SerieModel::list() const
{
    return mList;
}

void SerieModel::setList(SerieList *list)
{
    beginResetModel();

    if (mList)
        mList->disconnect(this);

    mList = list;

    if (mList) {
        connect(mList, &SerieList::preItemAppended, this, [=]() {
            const int index = mList->items().size();
            beginInsertRows(QModelIndex(), index, index);
        });
        connect(mList, &SerieList::postItemAppended, this, [=]() {
            endInsertRows();
        });
       }
    endResetModel();


}

seriemodel.h

#ifndef SERIEMODEL_H
#define SERIEMODEL_H

#include <QAbstractListModel>

class SerieList;

class SerieModel : public QAbstractListModel
{
    Q_OBJECT
    Q_PROPERTY(SerieList *list READ list WRITE setList)

public:
    explicit SerieModel(QObject *parent = nullptr);

    enum {
        SelectionRole = Qt::UserRole,
        NomRole,
        SerieRole,
        IDRole
    };

    // Basic functionality:
    int rowCount(const QModelIndex &parent = QModelIndex()) const override;

    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;

    // Editable:
//    bool setData(const QModelIndex &index, const QVariant &value,
//                int role = Qt::EditRole) override;

    Qt::ItemFlags flags(const QModelIndex& index) const override;

    virtual QHash<int, QByteArray> roleNames() const override;

    SerieList *list() const;
    void setList(SerieList *list);

private:
    SerieList *mList;
};

#endif // SERIEMODEL_H

In QML I would like for example:

ListView {
            implicitWidth: parent.width
            implicitHeight:parent.height
            anchors.fill: parent
            clip: true

            model: SerieModel {
                list: serieList
            }

            delegate: RowLayout {
                width: parent.width
                height: 30

                CheckBox {
                    checked: model.selection
                    onClicked: {model.selection = checked;serieList_activePlot.appendItem(model.serie);} //HERE I would like to use model.serie
                }

                Text {
                    text: model.nom
                    Layout.fillWidth: true
                    minimumPixelSize: 10
                }

Thank you in advance if someone can help me to handle this pointer in order to use it in my model.serie.

Regards,
JC

[raven-worx]

@JorisC
the only way to make QML aware of the "serie_graphe" type is by letting "serie_graphe" derive from QObject.
Otherwise you would need to route each member/property of "serie_graphe" with adedicated item role.
Or convert your "serie_graphe" to a QVariantMap (key-value like)

[jalali_shikha]

@JorisC said in Using pointer in C++ model for QML:

    return QVariant(item.serie);            //PROBLEM HERE because item.serie is a pointer .... and cannot be handle with QVARIANT

You can use return QVariant::fromValue(item.serie);