How to load a c++ treeModel in QML TreeView dynamicaly

buckTarle

Hello guys ! I just started to deal with QML and I have been kind of stuck with qml treeViews.

Here is what I have :

I have a working treeModel in C++ ( with the QAbstractItemModel class )

I have this line in the main.cpp wich ,I assume, allow my qml file to find it :

engine.rootContext()->setContextProperty("currentTreeModel",myTreeModel);

Than I construct my treeView with :

TreeView {

        id : treeView
        anchors.fill: parent
        model : currentTreeModel;

        TableViewColumn {
            role: "role"
            title: "title"
        }
}

It's working good and I get a nice treeView

Here is the problem :

I want my model to be rebuilt each time the user pick a new kind of data and I have no clue how to do so ...

What I have tried :

I have tried to make a function that return me a treeModel and make something like

TreeView {

        id : treeView
        anchors.fill: parent
////////////////////////////////////
        model  : getModel();
////////////////////////////////////
        TableViewColumn {
            role: "role"
            title: "title"
        }
}

with a c++ function like that :

Q_INVOKABLE TreeModel getModel()
{
  . . .
  . . .
  . . .
  return newTreeModel;
}

but it won't compile because a model cannot be copied

Do someone know how to deal with it or at least have any clue ?
Is it somehow possible to "redeclare" to the engine a new model ?

Thank you for helping

raven-worx

@buckTarle
are the models similiar regarding their structure?
Basically it's simply enough to reset the model and fill it with new data.

buckTarle

Hmmm not sure about what do you mean by similar.

They should be quite similar in fact all item are based on the same C structure so they have the same roles.
But they do not have the same tree-form and not the same lenght.

raven-worx

@buckTarle said in How to load a c++ treeModel in QML TreeView dynamicaly:

They should be quite similar in fact all item are based on the same C structure so they have the same roles.

yes that was what i meant.
Then simply update your model by doing the following and your qml view also updates:

void MyModel::refreshData()
{
     this->beginResetModel();
     // remove old data and re-initialize new data here
     this->endResetModel();
}

buckTarle

Ok I'm going to give it a try ! Thank you very much.

buckTarle

ok so i finaly got it to work with tons of tries !

I implemented the refreshData() method but I have had hard time figuring out how to pass the data needed for the new model.

I end up declaring the TreeModel as a static atribute using a static member of another class I use in my project. The other class is Registered in the main.cpp like that :

    qmlRegisterType<MyClass>("com.myself", 1, 0, "MyClass");

class MyClass : public QObject
{
    Q_OBJECT
public
    Q_INVOKABLE void reloadModel();
    Q_INVOKABLE TreeModel* getModel();
private :
    static TreeModel* m_currentModel;

The first call to the model will allocate one and than I am sure to get the same pointer every time I want to modify data in it.

I'm not sure this is the cleanest way to go but It's working for now !

Thank for helping raven-worx

raven-worx

@buckTarle said in How to load a c++ treeModel in QML TreeView dynamicaly:

I'm not sure this is the cleanest way to go but It's working for now !

yes, thats actually perfect for shared models.