Model Roles with children C++ classes

Karim

Hi,

I'm currently pototyping a kind of AVOD portal in QML with a Qt based C++ backend for the media catalog.
I basically have a kind of MediaObject base c++ class with children classes for MediaMovie, MediaAudio (mp3, albums) and MediaStream.

I've planed to implement a flickable object with each media cover, and as soon as a media is selected, display the related media data, depending of its type (movie, audio or stream).

Until then, I've never faced this issue, I used to have a model with roles accessed in the delegate.

In that particular case, roles might depend on the type of the media. In C++, this case might be fixes with the visitor pattern.
But how could it be handled with QML ?

Any suggestion is welcome.

Cheers.

K.

fcarney

@Karim said in Model Roles with children C++ classes:

But how could it be handled with QML ?

DelegateChooser

SGaist

Hi,

You may have missed the Qt Quick model view chapter in Qt's documentation. I think it should contain the information you are looking for.

Karim

Hello,

Of course I already read it for a while !
But its content is not focused on model with model-data classes with inheritance.

K

SGaist

You would like something like a dynamic delegate to match the underlying object ?

How big are the differences between your media classes ?

fcarney

If you want to return a QAbstractList/ItemModel you can do that as a role:

     QVariant value;
...
     case modelRole:

        value = QVariant::fromValue(m_somemodel); // object based upon QObject* or QAbstractItemModel* or similar
        break;

Edit: This is in the data() function call and value is returned.