implementation/design quesiton

[AlphaX2]

Hi,

I'm a bit new to C++, but know Qt/QML more or less from PySide. But now I stuck a bit.

My GUI is written in QML, you select 3 different things and depending on the selection, different *.ics files are parsed, to do that I have a class (Freiertag) with a search method (all in seperate cpp/hpp) which is bound to QML via setContextProperty and I have a ListModel (FreiListModel) also bound to QML. My problem is the following: I don't know how to let the both parts communicate. How to transfer the parsed data (QStringList) from Freiertag to the model? The model has it's own function addEvent(), which I wanted to use.

So my idea was:
1. create a new instance of the model in main.cpp.
2. create instance of Freiertag (which offers parsing function) and pass the model by address to the Freiertag object
3. bind both via setContextProperty to QML
4. access the model in Freiertag and use the addEvent() function

I thought, if the model is passed by address and not const, it's data will change and it can be bound to QML as well.
But if I pass it in this way, it's can not be accessed from the parser/search function, in the constructor it is possible to call the addEvent() function, but not from anywhere else! I think it's not public in the other scopes, but how to "say" in the header that I want the passed Model available for public access?!

I think it's more a C++ sepcific question, but I did not find any example and maybe someone has a better idea?!

AlphaX2

[anda_skoa]

Can you post at least the header of Freiertag, of the model and how you create the two instance you already export?

Cheers,
_

[AlphaX2]

Thank you for this fast answer!

Here are the code, I hope it's okay to post it here, if PasteBin is better please let me know!


Freiertag.hpp

#ifndef FREIERTAG_HPP_
#define FREIERTAG_HPP_
 
#include <QObject>
#include <QString>
#include <QDebug>
 
#include "FreiListModel.hpp"
 
 
class Freiertag : public QObject {
	Q_OBJECT
 
public:
    Freiertag(FreiListModel *model, QObject *parent = 0);
    //FreiListModel freiModel; // use here the passed model?!
    Q_INVOKABLE void suche(QString bland, QString jahr, QString typ);
 
	~Freiertag();
 
private:
	void sucheFerien(const QString &bland, const QString &jahr);
	void sucheFeiertage();
	void sucheAlleFeiertage();
};
#endif /* FREIERTAG_HPP_ */

#ifndef FREIERTAG_HPP_
#define FREIERTAG_HPP_

#include <QObject>
#include <QString>
#include <QDebug>

#include "FreiListModel.hpp"


class Freiertag : public QObject {
	Q_OBJECT

public:
    Freiertag(FreiListModel *model, QObject *parent = 0);
    //FreiListModel freiModel; // use here the passed model?!
    Q_INVOKABLE void suche(QString bland, QString jahr, QString typ);

	~Freiertag();

private:
	void sucheFerien(const QString &bland, const QString &jahr);
	void sucheFeiertage();
	void sucheAlleFeiertage();
};
#endif /* FREIERTAG_HPP_ */

To copy to clipboard, switch view to plain text mode 

FreiListModel.hpp

ifndef FREILISTMODEL_HPP_
#define FREILISTMODEL_HPP_
 
#include <QAbstractListModel>
#include <QVariant>
#include <QList>
#include <QString>
 
 
class FreiEvent
{
public:
	QString eventName;
	QString eventDate;
 
	FreiEvent();
	FreiEvent(QString event, QString date);
	~FreiEvent();
};
 
 
class FreiListModel : public QAbstractListModel
{
	Q_OBJECT
 
	enum ModelRoles {
		EventRole = Qt::UserRole + 1,
		DateRole
	};
 
public:
    FreiListModel(QObject *parent = 0);
 
	int rowCount(const QModelIndex &parent) const;
	QVariant data(const QModelIndex &parent, int role=Qt::DisplayRole) const;
 
	void addEvent(QString event, QString date);
	void printInfo();
 
	~FreiListModel();
 
private:
	QList<FreiEvent> resultList;
 
};
#endif /* FREILISTMODEL_HPP_ */

ifndef FREILISTMODEL_HPP_
#define FREILISTMODEL_HPP_

#include <QAbstractListModel>
#include <QVariant>
#include <QList>
#include <QString>


class FreiEvent
{
public:
	QString eventName;
	QString eventDate;

	FreiEvent();
	FreiEvent(QString event, QString date);
	~FreiEvent();
};


class FreiListModel : public QAbstractListModel
{
	Q_OBJECT

	enum ModelRoles {
		EventRole = Qt::UserRole + 1,
		DateRole
	};

public:
    FreiListModel(QObject *parent = 0);

	int rowCount(const QModelIndex &parent) const;
	QVariant data(const QModelIndex &parent, int role=Qt::DisplayRole) const;

	void addEvent(QString event, QString date);
	void printInfo();

	~FreiListModel();

private:
	QList<FreiEvent> resultList;

};
#endif /* FREILISTMODEL_HPP_ */

To copy to clipboard, switch view to plain text mode 

part of main.cpp

//create a new ListModel for the results
    FreiListModel *freiModel = new FreiListModel(app);
 
    //create a new instance of our object that is doing the most work
    Freiertag *frei = new Freiertag(freiModel, app);
 
    QDeclarativeView viewer;
 
    viewer.rootContext()->setContextProperty("frei", frei);
    viewer.rootContext()->setContextProperty("freiModel", freiModel);

//create a new ListModel for the results
    FreiListModel *freiModel = new FreiListModel(app);

    //create a new instance of our object that is doing the most work
    Freiertag *frei = new Freiertag(freiModel, app);

    QDeclarativeView viewer;

    viewer.rootContext()->setContextProperty("frei", frei);
    viewer.rootContext()->setContextProperty("freiModel", freiModel);

To copy to clipboard, switch view to plain text mode 

Thank you!

AlphaX2

[anda_skoa]

That looks good as far as I can tell.

What you are currently missing (if I understand your goal correctly) is a member in Freiertag that keeps the model pointer around.

Something like

class Freiertag : public QObject {
	Q_OBJECT
 
public:
    Freiertag(FreiListModel *model, QObject *parent = 0);
    //FreiListModel freiModel; // use here the passed model?!
    Q_INVOKABLE void suche(QString bland, QString jahr, QString typ);
 
	~Freiertag();
 
private:
	void sucheFerien(const QString &bland, const QString &jahr);
	void sucheFeiertage();
	void sucheAlleFeiertage();
 
private:
  FreiListModel *m_model;
};

class Freiertag : public QObject {
	Q_OBJECT
 
public:
    Freiertag(FreiListModel *model, QObject *parent = 0);
    //FreiListModel freiModel; // use here the passed model?!
    Q_INVOKABLE void suche(QString bland, QString jahr, QString typ);
 
	~Freiertag();
 
private:
	void sucheFerien(const QString &bland, const QString &jahr);
	void sucheFeiertage();
	void sucheAlleFeiertage();

private:
  FreiListModel *m_model;
};

To copy to clipboard, switch view to plain text mode 

And initialize the member like this from the constructor argument:

Freiertag::Freiertag(FreiListModel *model, QObject *parent)
  : QObject(parent)
  , m_model(model)
{}

Freiertag::Freiertag(FreiListModel *model, QObject *parent)
  : QObject(parent)
  , m_model(model)
{}

To copy to clipboard, switch view to plain text mode 

Then you have access to the model througout Freiertag's methods.

Cheers,
_

[AlphaX2]

Hmm it seems to be thing I was looking for, because qDebug() << m_model and qDebug() << freiModel gives me in: "FreiListModel(0x70658890)" So the memory seems to be the same, so the model seems to be the same.
My plan was, to explain it a bit better, to pass the model by reference/adress to Freiertag, but make it not const or something, so that the data can be changed from Freiertag and also the changes are visible in QML so in the end I want m_model and also freiModel (main.cpp) to be the exact same object. Both QML and Freiertag should "share" the same object and so the same data. Hope that makes it more clear what the plan is.

But in the QML ListView is not any result shown, also if I try to add some directly with m_model->addEvent("Test", "Date"). Not sure - is there a signal that have to be emited, that QML "knows" that something changed?!

I'm not sure whats wrong.

[AlphaX2]

Okay, I think I got it. I added a this->reset() in the method addEvent of the model, because this forces the Model/View to update. Maybe not the best solution, but not really clear to me, how to get the dataChanged() signal to work, because it want that I pass two QModelIndex Objects, but how to create them with the right indezes?!

AlphaX2

[anda_skoa]

Since you are adding something to the model you have to call beginInsertRows() before adding, then add, then call endInsertRows().
Since you are in a list model, the parent model index for beginInsertRows() is the invalid model index, i.e. QModelIndex()

Cheers,
_

[AlphaX2]

That's it! Thank you very much! I pass to the method just a QModelIndex and 0 as beginn and <mylistofdata>.length() as end. This works very well!

Thanks again!

AlphaX2