QAbstractListModel & QML

[qdlbp]

Hello

I have some problems to get my qml to work with a QAbstractListModel.

Here is my code:

Data.h
@
#ifndef DATA_H
#define DATA_H

#include <QAbstractListModel>
#include <QApplication>
#include <QDebug>
#include <QHash>
#include <QList>
#include <QObject>
#include <QVariant>
#include <QVariantMap>

class Data : public QAbstractListModel
{
Q_OBJECT

protected:
Data(QObject *parent);

private:
enum Role
{
Role_Name = Qt::UserRole + 1,
Role_Age
};

public:
static Data* instance();

private:
QHash<int, QByteArray> mRoleNames;
QList<QVariantMap> mItems;

public:
virtual QHash<int, QByteArray> roleNames() const;
virtual QVariant data(const QModelIndex &index, int role) const;
virtual int rowCount(const QModelIndex &) const;
};

#endif // DATA_H
@

Data.cpp
@
#include "Data.h"

Data::Data(QObject *parent)
: QAbstractListModel(parent)
{
mRoleNames[Role_Name] = "name";
mRoleNames[Role_Age] = "age";

for (int i = 0; i < 10; ++i)
{
    QVariantMap item;

    item[mRoleNames[Role_Name]] = QString("Name %1").arg(i);
    item[mRoleNames[Role_Age]]  = i;

    mItems << item;
}

}

Data *Data::instance()
{
static Data *p = new Data(qApp);
return p;
}

QHash<int, QByteArray> Data::roleNames() const
{
return mRoleNames;
}

QVariant Data::data(const QModelIndex &index, int role) const
{
Q_ASSERT(index.isValid());

if ((role >= Role_Name) && (role <= Role_Age))
{
    return mItems[index.row()][mRoleNames[role]];
}

return QVariant();

}

int Data::rowCount(const QModelIndex &) const
{
return mItems.count();
}
@

main.cpp
@
#include <QApplication>
#include <QQmlApplicationEngine>
#include <QtQml>

#include "Data.h"

int main(int argc, char *argv[])
{
QApplication app(argc, argv);

QQmlApplicationEngine engine;
engine.rootContext()->setContextProperty("data", Data::instance());
engine.load(QUrl(QStringLiteral("qrc:///main.qml")));

return app.exec();

}
@

main.qml
@
import QtQuick 2.2
import QtQuick.Controls 1.1

ApplicationWindow {
visible: true
width: 300
height: 300
title: qsTr("Hello World")

ListView {
    anchors.fill: parent
    model: data
    delegate: Text {
        text: name + ", " + age
    }
}

}
@

When i run the application i get this message:
@
QQmlExpression: Expression qrc:///main.qml:68:16 depends on non-NOTIFYable properties: QQuickListView::data
@

Also i see that no one methods of the Data class, except instance(), are called.

What is wrong with my code?

[hpollak]

You hava to implement the notification if the data changed.

There is a good tutorial about C++ models to QML "see: ":http://lemirep.wordpress.com/2013/04/06/a-practical-case-exposing-qt-c-models-to-qml/

[qdlbp]

Thanks for your reply.

But in the "documentation":http://qt-project.org/doc/qt-5/qtquick-modelviewsdata-cppmodels.html#qabstractitemmodel i found next:
@A QAbstractItemModel can also automatically notify a QML view when the model data changes.@

[qdlbp]

I modified my Data.cpp:
@
#include "Data.h"

Data::Data(QObject *parent)
: QAbstractListModel(parent)
{
qDebug() << "Data::Data()";
mRoleNames[Role_Name] = "name";
mRoleNames[Role_Age] = "age";

const int n = 10;

beginInsertRows(QModelIndex(), 0, n);

for (int i = 0; i < n; ++i)
{
    QVariantMap item;

    item[mRoleNames[Role_Name]] = QString("Name %1").arg(i);
    item[mRoleNames[Role_Age]]  = i;

    mItems << item;
}
qDebug() << mItems.count();

endInsertRows();

}

Data *Data::instance()
{
qDebug() << "Data::instance()";
static Data *p = new Data(qApp);
return p;
}

QHash<int, QByteArray> Data::roleNames() const
{
qDebug() << "Data::roleNames()";
return mRoleNames;
}

QVariant Data::data(const QModelIndex &index, int role) const
{
qDebug() << "Data::data()";
Q_ASSERT(index.isValid());

if ((role >= Role_Name) && (role <= Role_Age))
{
    return mItems[index.row()][mRoleNames[role]];
}

return QVariant();

}

int Data::rowCount(const QModelIndex &) const
{
qDebug() << "Data::rowCount()" << mItems.count();
return mItems.count();
}
@

So now i get this output:
@
Data::instance()
Data::Data()
Data::rowCount() 0
10
QQmlExpression: Expression qrc:///main.qml:76:16 depends on non-NOTIFYable properties: QQuickListView::data
@

Strange...

[fxam]

Change the model name in QML's ListView to something other than data, seems like it is referring to Item's "data":http://qt-project.org/doc/qt-5/qml-qtquick-item.html#data-prop property. I renamed my working model to data and had the same error.

[qdlbp]

Oh, right. Thanks