Error: 'qt_metatype_id' is not a member of 'QMetaTypeId<PlaylistModel>'

Hedge

I subclassed QAbstractListModel and wanted to use an instance of the subclass in a qml-file.
However I get the error:

@error: 'qt_metatype_id' is not a member of 'QMetaTypeId<PlaylistModel>'@

These are the headers of my subclass:

@class PlaylistModel : public QAbstractListModel {
Q_OBJECT
public:
enum PlaylistRoles {
TrackRole = Qt::UserRole
};

PlaylistModel(QObject *parent = 0);

    void addTrack(const QString &trackName);
    int rowCount(const QModelIndex & parent = QModelIndex()) const;
    QVariant data(const QModelIndex & index, int role = Qt::DisplayRole) const;

private:
     QStringList m_playlist;

};
@

This is the source:

@PlaylistModel::PlaylistModel(QObject *parent)
: QAbstractListModel(parent)
{
QHash<int, QByteArray> roles;
roles[TrackRole] = "track";
setRoleNames(roles);
}

int PlaylistModel::rowCount(const QModelIndex & parent) const {
return this->m_playlist.count();
}

QVariant PlaylistModel::data(const QModelIndex & index, int role) const {
if (index.row() < 0 || index.row() > this->m_playlist.count())
return QVariant();

const QString &track = this->m_playlist[index.row()];
    return track;

return QVariant();

}

void PlaylistModel::addTrack(const QString &trackName)
{
beginInsertRows(QModelIndex(), rowCount(), rowCount());
//m_playlist.append(trackname);
m_playlist << trackName;
endInsertRows();
}@

and this the part where I instantiate it and set the context property for use in the qml-file:

@ PlaylistModel playlistModel;
playlistModel.addTrack("Item 1");
playlistModel.addTrack("Item 2");

context->setContextProperty("myModel", QVariant::fromValue(playlistModel));@

What am I doing wrong?

ZapB

Do you mean in a QML file rather than XML file? If so you need to add:

@
qmlRegisterType<PlaylistModel>( "MyComponents", 1, 0, "PlaylistModel" );
@

before you try to set the "myModel" context property. This just registers your custom type with the QML backend.

You also need to add:

@
import MyComponents 1.0
@

to the QML file where you use it.

Hedge

Yeah, I meant qml instead of xml.

I added what you said but the error remains.

I am using the model like this in my qml-file:

@ TableView{

                        HeaderSection {
                            property: "track"
                            caption: "Track"
                            width: 200

                        }

                        model: myModel
                        width: 200
                        height: 100

                        itemDelegate: Rectangle {
                                 height: 25
                                 width: 100
                                 Text { text: track }
                             }
                    }@

This is a screenshot of the whole output of the error:
http://img843.imageshack.us/img843/2239/qterror2.png

ZapB

Ah sorry I missed a step. You also need to add:

@
Q_DECLARE_METATYPE( PlaylistModel* )
@

at the end of your model's header file which will let the metatype system know about pointers to your model.

Then I just noticed that you expose the model incorrectly. Your code should look like this instead:

@
context->setContextProperty("myModel", &playListModel );
@

Although beware, your model is created on the stack and so wil be deleted when it goes out of scope at the end of that function. It would be better to add

@
PlayListModel* m_playListModel;
@

as a member of whatever class it is that exposes it to the qml side of things.

Hedge

It compile now but the qml-part complains that:

@qrc:/desktop-components/components/TableView.qml:278: TypeError: Result of expression 'root.model.get' [undefined] is not a function.@

I set the context in the main-function so I should be alright but thanks for the tip.

Here is the source of TableView.qml if it's needed:
http://qt.gitorious.org/qt-components/desktop/blobs/master/components/TableView.qml

EDIT: It works with a ListView, so I must be doing something wrong with the TableView:

@ ListView{
model: myModel
width: 200
height: 100
delegate: Rectangle {
height: 25
width: 100
Text { text: track }
}
}@

ZapB

OK. I have never used TableView so I can't really help you with that. Maybe someone else here has experience with it? Does TableView ship with a demo that shows it's usage?

Hedge

Here's the example which comes shipped with it:
http://qt.gitorious.org/qt-components/desktop/blobs/master/examples/ModelView.qml

The part which shows it's usage is this:

@XmlListModel {
id: flickerModel
source: "http://api.flickr.com/services/feeds/photos_public.gne?format=rss2&tags=" + "Qt"
query: "/rss/channel/item"
namespaceDeclarations: "declare namespace media="http://search.yahoo.com/mrss/";"
XmlRole { name: "title"; query: "title/string()" }
XmlRole { name: "imagesource"; query: "media:thumbnail/@url/string()" }
XmlRole { name: "credit"; query: "media:credit/string()" }
}

TableView{
    model: flickerModel
    anchors.fill: parent

    HeaderSection {
        property: "title"
        caption: "Title"
        width: 120
    }
    HeaderSection {
        property: "credit"
        caption: "Credit"
        width: 120
    }
    HeaderSection {
        property: "imagesource"
        caption: "Image source"
        width: 200
        visible: true
    }
 
}

@

Jens

The TableView is a completely new design I haven't actually tried it out on much code yet so I am eager to get feedback on it. Just providing a StringList is not enough since you have to tell the TableView what information to put in each column. The treeview in the example can also be populated like this:

ListModel {
ListElement{title:"a title" ; imageSource: "some source" ; caption: "a caption"
ListElement{title:"a title" ; imageSource: "some source" ; caption: "a caption"
}
}

But as you see, it is important that you provide the proper named property and assign a HeaderSection to show it in a column. If you have a c++ model you need to map this yourself. I believe you can look at the dirmodel used by the qmlviewer source code itself as an example. Note that I still have some performance issues when scrolling on large lists, so it doesn't scale too well at the moment. But I will work on this. Emphasis has been functionality and styling so far.

Hedge

Thanks for jumping in on the discussion, Jens.

The approach you've shown (via ListModel) works but how do I map any data-structures to create List-elements?

I thought subclassing QAbstractListModel should work.

Jens

I googled a bit and found this blog. It seems to explain what you want:
http://cdumez.blogspot.com/2010/11/how-to-use-c-list-model-in-qml.html