QML ListView in qml is not updated when model changed

lomilomi

I am trying to update a model in a QML ListView from a cpp file..

this is my model implementation albummodel.h



#include <QAbstractListModel>
#include <QStringList>
#include <QQmlListProperty>

class Album
{
public:
    Album(const QString &type, const QString &size);


    QString type() const;
    QString size() const;

private:
    QString m_type;
    QString m_size;

};

class AlbumModel : public QAbstractListModel
{
    Q_OBJECT
    Q_PROPERTY(QQmlListProperty<QObject> myModel NOTIFY listChanged)

public:

    enum AlbumRoles {
        TypeRole = Qt::UserRole + 1,
        SizeRole
    };

    AlbumModel(QObject *parent = 0);

    //QQmlListProperty<QObject> getList();

    void addAlbum(const Album &album);

    int rowCount(const QModelIndex & parent = QModelIndex()) const;

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

protected:
    QHash<int, QByteArray> roleNames() const;
private:
    QList<Album> m_albums;
signals:
    void listChanged();
#include <QAbstractListModel>
#include <QStringList>
#include <QQmlListProperty>

class Album
{
public:
    Album(const QString &type, const QString &size);


    QString type() const;
    QString size() const;

private:
    QString m_type;
    QString m_size;

};

class AlbumModel : public QAbstractListModel
{
    Q_OBJECT
    Q_PROPERTY(QQmlListProperty<QObject> myModel NOTIFY listChanged)

public:

    enum AlbumRoles {
        TypeRole = Qt::UserRole + 1,
        SizeRole
    };

    AlbumModel(QObject *parent = 0);

    //QQmlListProperty<QObject> getList();

    void addAlbum(const Album &album);

    int rowCount(const QModelIndex & parent = QModelIndex()) const;

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

protected:
    QHash<int, QByteArray> roleNames() const;
private:
    QList<Album> m_albums;
signals:
    void listChanged();
};

This is my albummodel.cpp

#include "albummodel_mediaplayer.h"

Album::Album(const QString &type, const QString &size)
    : m_type(type), m_size(size)
{
}

QString Album::type() const
{
    return m_type;
}

QString Album::size() const
{
    return m_size;
}

AlbumModel::AlbumModel(QObject *parent)
    : QAbstractListModel(parent)
{
}

void AlbumModel::addAlbum(const Album &album)
{
    beginInsertRows(QModelIndex(), rowCount(), rowCount());
    m_albums << album;
    endInsertRows();

    emit listChanged();
}

int AlbumModel::rowCount(const QModelIndex & parent) const {
    Q_UNUSED(parent);
    return m_albums.count();
}

QVariant AlbumModel::data(const QModelIndex & index, int role) const {
    if (index.row() < 0 || index.row() >= m_albums.count())
        return QVariant();

    const Album &Album = m_albums[index.row()];
    if (role == TypeRole)
        return Album.type();
    else if (role == SizeRole)
        return Album.size();
    return QVariant();
}


QHash<int, QByteArray> AlbumModel::roleNames() const {
    QHash<int, QByteArray> roles;
    roles[TypeRole] = "type";
    roles[SizeRole] = "size";
    return roles;
}


/*QQmlListProperty<QObject> AlbumModel::getList(){
    return QQmlListProperty<QObject>(this, *list);
}*/

and my qml file

ListView {
model: myModel

....
}

But the model isn't updated.....Can someone help me to get the connection right?

sierdzio

@lomilomi said in QML ListView in qml is not updated when model changed:

Q_PROPERTY(QQmlListProperty<QObject> myModel NOTIFY listChanged)

This is wrong, you don't need any Q_PROPERTY when using a QAbstract*Model.

In QML, you should simply point model to an instance of AlbumModel. I don't know how you create/ pass it from C++ to QML so I can't exactly tell you how to do it in your case.

In general, though, setting it through root context property of the QQmlEngine is the easiest route and works well.

lomilomi

@sierdzio

This is my main program

void main() {
      qmlRegisterType<AlbumModel>("AlbumModel",1,0,"AlbumModel");
      Album g("test", "test");
       AlbumModel h();
       h.addAlbum(g);
  }

Qml file

import AlbumModel 1.0 ListView { model: AlbumModel.myModel delegate: playListThumbnail Component { id: playListThumbnail

            Item {
 Text {
                    id: albumTitleText
                    text:  type//item_title 
}}
....
}

sierdzio

You create 2 different instances of AlbumModel: one in C++ and one in QML. Then you add an album in C++ - but obviously the other object in QML won't know about it.

Solution: do not create 2 objects. For example, in C++:

void main() {
      Album g("test", "test");
       AlbumModel h();
       h.addAlbum(g);
       engine.rootContext()->setContextProperty("AlbumModel", &h);
  }

With this it should work fine.

VRonin

This is almost verbatim the same as this example on the wiki