Getting the Value of a Enum Name from QML

Throndar

Hello,

I use a self-declared QAbstractListModel on which I add Objects to it with initialized Base values. To change the Values or set Values not initialized on start I override the setData Function.

This all works fine but I to Change a Property I need int of the Role I want to Change. So I wonder if there is a way to get the integer of the role by its name to use it in the setData Function. At the Moment if change a Property of an Item I call something like:

MovieClientModel.setData(MovieClientModel.index(row, 0), "New Value", 256);

where 256 is the Integer of the Role in the Enum. Is there a way to access the Integer of the Enum by its name from QML?

Gojir4

@Throndar Hi, you probably need to implement method QAbstractListModel::rolesNames() in your model.

//.cpp
QHash<int, QByteArray> MyModel::roleNames() const
{
    QHash<int, QByteArray> roles = QAbstractListModel::roleNames();
    roles[MyRole1] = "role1";
    roles[MyRole2] = "role2";
    return roles;
}

Then you can use

MovieClientModel.setData(MovieClientModel.index(row, 0), "New Value", "role1");

Pablo J. Rogina

@Throndar you may want to take a look at this post, as it may give you an idea of using C++ stuff in QML by registering the class(es)

Throndar

Hello @Gojir4 ,

I am a little bit confused, I allready use the "roleNames()" Function (cut to only a few Values): (added the = QAbstractListModel::rolesNames() which I didn't have in my Function

QHash<int, QByteArray> MovieClientModel::roleNames() const
{
    QHash<int, QByteArray> roles  = QAbstractListModel::roleNames();
    roles[NameRole] = "name";
    roles[AddressRole] = "address";
    roles[VersionRole] = "version";
    roles[PortRole] = "port";
    return roles;
}

but when I trie to use

MovieClientModel.setData(MovieClientModel.index(row, 0), "new Value", "name");

the Property don't get set (like if I use the integer of the Enum).

To be sure the setData isn't wrong:

bool MovieClientModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
    if(!hasIndex(index.row(), index.column(), index.parent()) || !value.isValid())
            return false;

    MovieClient &movieClient = m_movieClients[index.row()];
    if(role == NameRole)
        movieClient.setName(value.toString());
    else if(role == AddressRole)
        movieClient.setAddress(value.toString());

    emit dataChanged(index, index, {role});
    return true;
}

But the setData only works with the Integer, on the name of the Role it didn't switch

Gojir4

@Throndar You are right, my bad, so in this case the solution from @Pablo-J-Rogina seems better.

But I'm not sure why you need to call setData from your code. Usually it is called by the model itself to handle data modification from a view.
From the delegate, you should be able to set the new value with something like:

name = "new value"
//or
styleData.name = "new value"

Diracsbracket

@Throndar
You already got the answer to that in your other post
https://forum.qt.io/topic/94461/access-list-of-objects-in-qml/8

The C++ enum item NameRole is not directly accessible in QML: You must register it using the Q_ENUM macro, but this requires you to register the MoveClientModel type too.
http://doc.qt.io/qt-5/qtqml-cppintegration-data.html#enumeration-types
When you do all the above, you can access the data as:
console.log(movieClientModel.data(movieClientModel.index(0,0), MovieClientModel.NameRole))

So:

You need to use the Q_ENUM macro
http://doc.qt.io/qt-5/qtqml-cppintegration-data.html#enumeration-types
You must register your class MovieClientModel
http://doc.qt.io/qt-5/qqmlengine.html#qmlRegisterType

Then, you can access the enum value in QML as e.g.

MovieClientModel.NameRole

And use that in your setData() function.

Throndar

Hello @Pablo-J.-Rogina,

thank you very much. It works perfectly now.

Throndar

Hello @Diracsbracket ,

thank you for your help, I really appreciate you helping me again.