using QList from c++ backend in QML

[Allerknappe]

Hello Guys,

i´ve tried to put my own backend c++ code in a QML model.
i write a new class with this code:

class DataObject : public QObject
{
    Q_OBJECT

    Q_PROPERTY(QString text READ text WRITE setText NOTIFY textChanged)
    Q_PROPERTY(QString detailText READ detailText WRITE setDetailText NOTIFY detailTextChanged)
 ...

i add then with:
QList dataList;
dataList.append(new DataObject(chat->kon[i]->getname(), QVariant(ia).toString()));

a new QList.

so far so good.
Now i add in the main.cpp with:

engine.rootContext()->setContextProperty("modelContact", QVariant::fromValue(cont->dataList));

a modelContact property.

so in the example code it´s in the qml code the following area that i want to change:

// Model should be loaded from your messaging backend
        //  model: [
        //    { text: "Tom McEloy", detailText: "Sorry for the late reply ...", image: Qt.resolvedUrl("../../assets/portrait0.jpg") },
        //    { text: "Leah Douglas", detailText: "Hahaha :D", image: Qt.resolvedUrl("../../assets/portrait1.jpg") }
        //  ]

so like the comment i want to load the model from the backend, so i try:

model: modelContact

but i get no text or detailtext, where is the problem?

[SGaist]

Hi,

Are you following the Using C++ Models with Qt Quick Views chapter of Qt's documentation ?

[Allerknappe]

yeah i used exactly this documentation.
i think that the model is correctly loaded, but how can i change this code

 // Model should be loaded from your messaging backend
        //  model: [
        //    { text: "Tom McEloy", detailText: "Sorry for the late reply ...", image: Qt.resolvedUrl("../../assets/portrait0.jpg") },
        //    { text: "Leah Douglas", detailText: "Hahaha :D", image: Qt.resolvedUrl("../../assets/portrait1.jpg") }
        //  ]

with the modelData object from the Using C++ Models with Qt Quick Views chapter documentation.
if i try this code

 model : [ { text: model.modelData.text } ]

nothing happen...

[SGaist]

Then I think you have to follow the Exposing C++ Data Model to QML.

[raven-worx]

@Allerknappe
QML can convert QLists using basic data types. For lists containing Items or QObjects you need to implement a QQuickListProperty property. See the birthday party example as reference.

[GrecKo]

A QQmlListProperty is needed when you want to populate a list declaratively from QML.

When you data is coming from c++, you can expose a list with a QList<QObject*> (but not a QList<DerivedFromQObject*>), a QVarantList or a QAbstractItemModel (a QAbstractListModel generally). The latter is more generic, allow more fine grained changes to the model and is more type safe.

Implementing a QAbstractItemModel can be a tedious task, if you don't want to do it yourself I recommend one of those 2 librairies : http://gitlab.unique-conception.org/qt-qml-tricks/qt-qml-models & https://github.com/benlau/qsyncable