QML TableView with dynamic number of columns

Question

I have been trying to use a QML TableView to display a QAbstractTableModel. The missing part of the equation seems to be that it is not possible to

Answer 1

You could create dynamically as many TableViewColumn as you need, using the resources property of your TableView.

You will have to add a method in your custom model class which will give you the roleNames you want to display.

QML:

Component
{
    id: columnComponent
    TableViewColumn{width: 100 }
}

TableView {
    id: view
    anchors.fill: parent
    resources:
    {
        var roleList = myModel.customRoleNames
        var temp = []
        for(var i=0; i<roleList.length; i++)
        {
            var role  = roleList[i]
            temp.push(columnComponent.createObject(view, { "role": role, "title": role}))
        }
        return temp
    }

    model: myModel

MyModel.h:

class MyModel: public QAbstractListModel
{
    Q_OBJECT
    Q_PROPERTY(QStringList userRoleNames READ userRoleNames CONSTANT)

public:
    explicit MyModel(QObject *parent = 0);

    enum MyModelRoles {
        UserRole1 = Qt::UserRole + 1,
        UserRole2,
        ...
    };

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

private:
    QHash<int, QByteArray> roleNames() const;
    ...

};

MyModel.cpp:

...
...

QHash<int, QByteArray> MyModel::roleNames() const {
    QHash<int, QByteArray> roles = QAbstractListModel::roleNames ();
    roles[UserRole1] = "whatever";
    roles[UserRole2] = "youwant";
    return roles;
}

QStringList MyModel::userRoleNames() // Return ordered List of user-defined roles
{
    QMap<int, QString> res;
    QHashIterator<int, QByteArray> i(roleNames());
    while (i.hasNext()) {
        i.next();
        if(i.key() > Qt::UserRole)
            res[i.key()] = i.value();
    }
    return res.values();
}

...
...

Answer 2

The solution with resources does not work for me (Qt 5.6). The TableView is not updated.

This works for me:

Component{
    id: columnComponent
    TableViewColumn{width: 30 }
}

TableView {
    id: tableView
    model: listModel
    property var titles: somethingDynamic
    property var curTitles: {
        var t=[]
        for(var i=0;i<columnCount;i++){
            t.push(getColumn(i).title)
        }
        return t
    }
    onTitlesChanged:{
        for(var i=0;i<titles.length;i++){
            if(curTitles.indexOf(titles[i])==-1){
                var column = addColumn(columnComponent) 
                column.title=titles[i]
                column.role=titles[i]                   
            }
        }
        for(var i=curTitles.length-1;i>=0;i--){
            if(titles.indexOf(curTitles[i])==-1){
                removeColumn(i)
            }
        }
    }
}

}

It also correctly updates drag-drop-reordered columns.