setContextProperty : why is a method of a contextProperty not recognized ?

[Quentin91]

hi !

I created two C++ class which instanciates two others as ContextProperties.
i can call a method of one of the class from the QML and it works fine when I launch it with a button. If I do the same with a method of the other object,
TypeError: Property 'savePreset' of object VIEW::PresetModel<adress> is not a function. Why ?

Here are the codes :
setContextProperties :

MainModelView* mp_mainModel;
PresetModel* mp_presetModel;
QQmlContext::PropertyPair m_mainModelProperty, m_presetModelProperty;

this->engine()->addImportPath(QString(QML_HOME));
mp_mainModel = new MainModelView(this); 
mp_presetModel = new PresetModel(this);
QVector<QQmlContext::PropertyPair> w_properties;
if (mp_mainModel && mp_mainModel)
{
	m_mainModelProperty.name = "MainModel";
	m_mainModelProperty.value = QVariant::fromValue(mp_mainModel);
	w_properties.append(m_mainModelProperty);
	m_presetModelProperty.name = "PresetModel";
	m_presetModelProperty.value = QVariant::fromValue(mp_presetModel);
	w_properties.append(m_presetModelProperty);
				
	this->engine()->rootContext()->setContextProperties(w_properties);
	//this->engine()->rootContext()->setContextProperty("MainModel",mp_mainModel);
	//this->engine()->rootContext()->setContextProperty("PresetModel", mp_presetModel);

(should I use two setContextProperty or one setContextProperties ? the documentation says it's better to set everything at one time but I have to create a vector, two objects, two QVariant casts... is it really more efficient ?)
Prototype of the methods of MainModelView that is working fine

Q_INVOKABLE void nameOfTheMethod(void);

QML programm that calls the method that works

 EditPanelButton {
        id: reset_button
        width: position === Qt.LeftEdge || position === Qt.RightEdge ? parent.width/1.5 : parent.height/1.5
        height: width
        x: position === Qt.LeftEdge || position === Qt.RightEdge ? parent.width/2-width/2 : parent.width-width-10
        y: position === Qt.LeftEdge || position === Qt.RightEdge ? parent.height-height-10 : parent.height/2-height/2
        text: "RESET"
        onClicked: {MainModel.resetParameters();console.log("reset_button clicked")}
}

and this call doesn't work

EditPanelButton {
        id: save_preset
        x: position === Qt.LeftEdge || position === Qt.RightEdge ? limit3.x : limit3.x + 10
        y: position === Qt.LeftEdge || position === Qt.RightEdge ? limit3.y + 10 : limit3.y
        width: position === Qt.LeftEdge || position === Qt.RightEdge ? parent.width/3 : parent.height/3
        height: width
        image: "../../resources/save-128.png"

        onClicked: { PresetModel.savePreset(); preset_view.currentIndex = preset_view.count-1;console.debug("EditPanel savepreset clicked") }
    }

how can I launch savePreset() as I launch resetParameters() ?

[dheerendra]

Can you show what is the PresetModel header file ? I suspect the issue with declaration of savePreset().

Can you try registering the objects using setContextProperty & check it works ?

[J.Hilk]

hi @Quentin91

is your

Q_INVOKABLE void nameOfTheMethod(void);

public ?

[Quentin91]

Thank you very much for your answers

@dheerendra sure, here is the declaration of the class

class PresetModel : public QAbstractListModel
		{
			Q_OBJECT
		private:
			QQuickView * mp_view;
			QList<Preset> m_preset_list;
			/*!
			*  \brief constructeur par copie
			*
			*	constructeur par copie privé
			*
			*	\param [IN] air_presetModel : référence à l'objet à copier.
			*/
			PresetModel(const PresetModel& air_presetModel);
			
			Preset* mp_preset_base;
		public:
			
			enum t_presetRole
			{
				NameRole = Qt::UserRole + 1
			} mstruct_roles;

			static const int ms_NameRole = Qt::UserRole +1;
			/*!
			*  \brief constructeur
			*
			*	\param [IN] aip_view : pointeur sur la QQuickView correspondant à la fenêtre principale
			*	\param [IN] aip_parent : parent QObject de la classe, null par défaut
			*/
			PresetModel(QQuickView* aip_view, QObject* aip_parent = nullptr);
			/*!
			*  \brief donne le nombre d'éléments du model
			*/
			~PresetModel();
			/*!
			*  \brief ajoute un modèle Preset à la fin de la QList
			*
			*	\param [IN] aip_p : référence const sur le Preset à ajouter
			*/
			void addPreset(const Preset& air_p);
			/*!
			*  \brief donne le nombre d'éléments du model
			*
			*	\param [IN] air_parent : QModelIndex& qui localise les données dans le model de données
			*	\return int : nombre de lignes du parent
			*/
			int rowCount(const QModelIndex& air_parent = QModelIndex())const override;
			/*!
			*  \brief donne accès à l'objet enregistré sous un certain index
			*
			*	\param [IN] air_index : QModelIndex& qui localise les données dans le model de données
			*	_param [IN] ai_role : int correspondant au role. Aucune idée de ce que c'est que cette histoire
			*	\return QVariant : nom de l'Item enregistré à l'index donné si tout va bien. Sinon, un QVariant vide
			*/
			QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
			/*!
			 *	\brief getter de mstruct_roles
			 * 
			 * \return t_presetRole : contenu de la structure. A savoir un integer
			 */
			t_presetRole roleName(void);
			/*!
			 * \brief initilialise un élément de base dans la liste
			 * 
			 */
			void setPresetBase(void);
			/*!
			 * \brief 
			 * 
			 * \param ai_index correspond à la configuration à charger
			 */
			Q_INVOKABLE void applyPreset(int ai_index);
			/*!
			* \brief sauvegarde la configuration actuelle
			*/
			Q_INVOKABLE void savePreset(void);
	
			/*!
			 * \brief charge les paramètres des items QML depuis un fichier
			 * 
			 */
			bool loadPresetFromFile(void);
		public slots:
		
		void onPresetChanged();

		};

Can you try registering the objects using setContextProperty & check it works ?

I tried again, the behaviour of the program is exactly the same. Do you think i should use 2 setContextProperty instead of setContextProperties ?

@J-Hilk Yes, the methods are public
Here is the definition of the method savePreset that can't get CALLED. As you can see, it's the simplest I can do.

void PresetModel::savePreset(void)
{
	TRACE_DEBUG("presetModel::savePreset....................CALLED");
        printf("but does nothing yet\n");
}