Exposing C++ model as Q_PROPERTY ?

[Babs]

Hello,
Is it possible to expose a C++ model as a Q_PROPERTY.
In my project , i have a class Planning containing a list of Object Palier that i must display as a table in QML. I create a model class for the object Palier.

class PalierModel: public QAbstractTableModel
{
    enum PalierDetails{
        valueRole=Qt::UserRole,
        debitRole=Qt::UserRole+1,
        distanceRole=Qt::UserRole+2,
        iradTimeRole=Qt::UserRole+3,
        debutRole=Qt::UserRole+4,
        finRole=Qt::UserRole+5,
        tempsMesRole=Qt::UserRole+6
    };

public:
    explicit PalierModel(QObject *parent= Q_NULLPTR);
    int rowCount(const QModelIndex &index=QModelIndex()) const override;
    int columnCount(const QModelIndex & = QModelIndex()) const override;
    QVariant data(const QModelIndex &index,int role=Qt::DisplayRole) const override;
    Qt::ItemFlags flags(const QModelIndex &index) const override;
    bool setData(const QModelIndex &index, const QVariant &value,int role) override;
    QHash<int,QByteArray> roleNames() const override;
    Planning *dataSource() const;
    void setDataSource(Planning *plan);

private:
    Planning *m_plan;
    bool m_signalConnected;
};

//Planning class

class Planning: public QObject
{
    Q_OBJECT
    Q_PROPERTY(int doseParameter READ doseParameter WRITE setDoseParameter NOTIFY doseParameterChanged)
    Q_PROPERTY(int numOfSteps READ numOfSteps WRITE setNumOfSteps NOTIFY numOfStepsChanged)
    Q_PROPERTY(double distance READ distance WRITE setDistance NOTIFY distanceChanged)
    Q_PROPERTY(int timeBetweenSteps READ timeBetweenSteps WRITE setTimeBetweenSteps NOTIFY timeBetweenStepsChanged)
    Q_PROPERTY(QString startManipTime READ startManipTime WRITE setStartManipTime  NOTIFY startManipTimeChanged)
    Q_PROPERTY(QTime startHour READ startHour WRITE setStartHour NOTIFY startHourChanged)
    Q_PROPERTY(QTime endHour READ endHour WRITE setEndHour NOTIFY endHourChanged)
    Q_PROPERTY(QTime tempsMesure READ tempsMesure WRITE setTempsMesure NOTIFY tempsMesureChanged)
    Q_PROPERTY(QString userName READ userName WRITE setUserName NOTIFY userNameChanged)
    Q_PROPERTY(PalierModel myModel READ myModel)

public:
    explicit Planning(QObject *parent=Q_NULLPTR);

public slots:

signals:

    void doseParameterChanged(int doseParameter);

    void numOfStepsChanged(int numOfSteps);

    void distanceChanged(double distance);

    void timeBetweenStepsChanged(int timeBetweenSteps);

    void startManipTimeChanged(QString startManipTime);

    void prePalierAdded();

    void postPalierAdded();

    void prePalierRemoved(int index);

    void postPalierRemoved();

    void startHourChanged(QTime startHour);

    void endHourChanged(QTime endHour);

    void tempsMesureChanged(QTime tempsMesure);

    void userNameChanged(QString userName);

private:
    QMap<int,Palier*> m_paliers;

};

#endif // PLANNING_H

I have a main class manager containing a list of objects Planning that i expose to QML.

#ifndef MANAGER_H
#define MANAGER_H

#include <QObject>

#include "planning.h"

class Manager:public QObject
{
    Q_OBJECT
public:
    Manager(QObject *parent=Q_NULLPTR);
   Q_INVOKABLE Planning * getPlanning(void);

public slots:
    Q_INVOKABLE void addPlanning(int i, Planning * plan);

private:
        QMap<int,QObject*> m_plannings;
};

#endif // MANAGER_H

My problem is that i need to display for each object planning a table in my QML. I will have multiple models thus. I'm wondering if i could just expose the model as Q_PROPERTY in classs Planning?
Can anyone help pls?

[Gojir4]

@Babs Hi,
Yes you can. You need to expose a pointer as property, and also register the type of the model so it's known by the Qml Engine.
Example :

Q_PROPERTY(QMyModel *myModel READ myModel NOTIFY myModelChanged)

You need to register the type before to use it, for example in the main() function:

int main(int argc, char *argv[]){
    QGuiApplication app (argc, argv);
    qmlRegisterType<MyModel>("MyApp.Core", 1, 0, "MyModel");
    //.... loading and initializing QML
    return app.exec()

Note that NOTIFY sinal is useless but only here to avoid the warning from Qml Engine "depends on non-NOTIFYable properties:"

[KroMignon]

@Gojir4 said in Exposing C++ model as Q_PROPERTY ?:

Note that NOTIFY sinal is useless but only here to avoid the warning from Qml Engine "depends on non-NOTIFYable properties:"

To avoid this warning, I guess it is better to declare the Q_PROTERTY as constant:

Q_PROPERTY(QMyModel *myModel READ myModel CONSTANT)

Another side note is to be aware of Data Ownership issues: ensure returned object instance has a parent or use QQmlEngine::setObjectOwnership(objectIntance, QQmlEngine::CppOwnership) to ensure Qml Engine will not take ownership and delete your object instance!

[raven-worx]

@Gojir4 said in Exposing C++ model as Q_PROPERTY ?:

You need to register the type before to use it, for example in the main() function:

i think its not mandatory to register it this way

[Babs]

Thanks you all. I'll try to do it.