QStandardItemModel appendRow doesn't update QML TreeView

BitteWenden

No idea?

SGaist

Hi,

Please practice some patience, allow 24 hours before bumping your own thread. Not all people on this forum live in the same timezone as you.

Did you follow the example about [Inserting and removing rows](http://doc.qt.io/qt-5/model-view-programming.html ?

BitteWenden

I guess? Do I need to reimplement insertRows? If so, how does that work for my QStandardItems?

SGaist

What did you change in you subclass regarding QStandardItemModel ?

BitteWenden

Nothing apart from custom roles I use in childEntry->setData.

class ProjectTreeModel : public QStandardItemModel
{
    Q_OBJECT
public:
    explicit ProjectTreeModel(QObject *parent = 0);
    virtual ~ProjectTreeModel() = default;

    Q_INVOKABLE QString initializeModel(QString dirLoation);
    enum ProjectTreeModel_Roles
    {
        ProjectTreeModel_Role_Name = Qt::DisplayRole,
        ProjectTreeModel_Role_Type = Qt::WhatsThisRole,
        ProjectTreeModel_Role_Icon = Qt::DecorationRole
    };

    QHash<int, QByteArray> roleNames() const override;

private:
    void addChildEntry( const QString& name, const QString& type, const QString& icon, QStandardItem parent);
    void addRootEntry( const QString& name, const QString& type, const QString& icon);
    QHash<int, QByteArray> m_roleNameMapping;
};

This is my class, so as you can see there is nothing really done with it.

SGaist

How/where are you appending rows outside the constructor ?

BitteWenden

In the addRootEntry (and later in the addChildEntry where it should add a child to a given QStandardItem) in reaction to a button press.

auto rootEntry = new QStandardItem( name );

    rootEntry->setData( icon, ProjectTreeModel_Role_Icon );
    rootEntry->setData( type, ProjectTreeModel_Role_Type );
    rootEntry->setData( name, ProjectTreeModel_Role_Name );

    invisibleRootItem()->appendRow(rootEntry);

This is what it does.

BitteWenden

Do I need to tell my view somehow that the model got updated?

SGaist

I'd emit dataChanged with the new index passing your custom roles.

BitteWenden

I added emit dataChanged(QModelIndex(), QModelIndex(), roles); after my appendRow, which should update the whole view(?), but it still doesn't work.

BitteWenden

This is my whole class right now, in case that helps:

ProjectTreeModel::ProjectTreeModel(QObject *parent) :
    QStandardItemModel(parent)
{

    m_roleNameMapping[ProjectTreeModel_Role_Name] = "name_role";
    m_roleNameMapping[ProjectTreeModel_Role_Type] = "type_role";
    m_roleNameMapping[ProjectTreeModel_Role_Icon] = "icon_role";


}

void ProjectTreeModel::addRootEntry( const QString& name, const QString& type, const QString& icon)
{
    auto rootEntry = new QStandardItem( name );

    rootEntry->setData( icon, ProjectTreeModel_Role_Icon );
    rootEntry->setData( type, ProjectTreeModel_Role_Type );
    rootEntry->setData( name, ProjectTreeModel_Role_Name );

    invisibleRootItem()->appendRow(rootEntry);
    qDebug() << rootEntry;
    qDebug() << this->rowCount();

    QVector<int> vector(0);
    vector.append(ProjectTreeModel_Role_Icon);
    vector.append(ProjectTreeModel_Role_Type);
    vector.append(ProjectTreeModel_Role_Name);

    emit dataChanged(QModelIndex(), QModelIndex(), vector);
}


QHash<int, QByteArray> ProjectTreeModel::roleNames() const
{
    return m_roleNameMapping;
}

SGaist

AFAIK, no. You are passing two invalid indexes. If you want to trigger a refresh, give the top left and bottom right indexes of the part of the model that should get refreshed on the view.

BitteWenden

Okay, tried it with emit dataChanged(invisibleRootItem()->index(), rootEntry->index(), vector); which should work, but it doesn't.

BitteWenden

Or at least I think that should update everything from the root item to the newly created entry.

SGaist

How are you adding that new row outside the constructor ?

BitteWenden

With the appendRow() method (on the invisible root item) as mentioned earlier.

SGaist

I meant, where are you calling appendRow ?

BitteWenden

In a function that is called in response to a button click. (that function calls addRootItem multiple times)

Orkblutt

What about using beginInsertRows() / endInsertRow() ?

BitteWenden

That doesn't seem to work either.