Migrate QTreeView to QML TreeView: how to manage multiples roles?

Question

I'm trying to rewrite my application using QML modules and droping Qt Widgets. I have a very complex QTreeView which is used to display Tracks, Albums and Artists.

Here's what I have right now:

I'm building subclasses of QStandardItem where I've redefined type() in order to paint them correctly in my delegate, like this:

switch (item->type()) {
    case Miam::IT_Album:
        this->paintRect(painter, o);
        this->drawAlbum(painter, o, item);
    break;
    case Miam::IT_Artist:
        this->paintRect(painter, o);
        this->drawArtist(painter, o, item);
    break;
    ...
    default:
    QStyledItemDelegate::paint(painter, o, index);
    break;
}

It was painful to write (managing brushes, pixels, drawing lines), but it worked quite well!

Now let's rewrite to QML

Work in progress:

My problem is to be able to display multiples data roles on the same column. From what I've understood, in QML you need to use a TableViewColumn for each Column of your TreeView (or TableView). And each column is mapped to a single role.

This is my work-in-progress TreeView:

TreeView {
    alternatingRowColors: false
    TableViewColumn {
        id: column
        title: qsTr("Artists")
        role: "text"
        delegate: Rectangle {
            implicitHeight: height
            implicitWidth: width
            color: Material.background
            Image {
                id: disc
                sourceSize.height: 20
                sourceSize.width: 20
                source: "qrc:/images/disc.png"
                visible: libraryItemModel.data("cover")
            }
            Label {
                anchors.left: disc.visible ? disc.right : undefined
                text: styleData.value
                color: Material.foreground
            }
        }
    }
    model: libraryItemModel
    anchors.top: parent.top
    anchors.bottom: parent.bottom
    anchors.left: parent.left
    anchors.rightMargin: jumpLetters.width
    anchors.right: parent.right
    horizontalScrollBarPolicy: Qt.ScrollBarAlwaysOff
    style: TreeViewStyle {
        backgroundColor: appSettings.menuPaneColor
        frame: Rectangle {
            border.width: 0

        }
    }
}

In my legacy LibraryItemModel class, I was doing stuff like this when reading my local SQLite database:

    auto loadTrack = [=] (QSqlRecord& r) -> TrackItem* {
    TrackItem *trackItem = new TrackItem;
    trackItem->setText(r.value(trackTitle).toString());
    trackItem->setData(r.value(uri).toString(), Miam::DF_URI);
    trackItem->setData(r.value(trackNumber).toString(), Miam::DF_TrackNumber);
    trackItem->setData(r.value(disc).toString(), Miam::DF_DiscNumber);
    trackItem->setData(r.value(trackLength).toUInt(), Miam::DF_TrackLength);
    if (r.value(rating).toInt() != -1) {
        trackItem->setData(r.value(rating).toInt(), Miam::DF_Rating);
    }
    trackItem->setData(r.value(artist).toString(), Miam::DF_Artist);
    trackItem->setData(r.value(album).toString(), Miam::DF_Album);
    trackItem->setData(!r.value(host).toString().isEmpty(), Miam::DF_IsRemote);
    return trackItem;
};

QSqlQuery q(...);
while (q.next()) {
    ...
    albumItem->appendRow(loadTrack(r));
}

What solutions do I have to make a multi-role Column? What else can I do? The line :

visible: libraryItemModel.data("cover")

doesn't work for instance.

Llamma Llamma · Accepted Answer · 2018-01-18T10:24:53

try model.text instead of styleData.value and remove the role property from the column.

With model.[role] you can get every role from the model for this specific item.

Migrate QTreeView to QML TreeView: how to manage multiples roles?

Now let's rewrite to QML

1 Answers