Accessing QAbstractItemModel fields in QML

[ODБOï]

hi,
I am trying to access model (QAbstractItemModel ) fields inside the itemDelegate of a QML TreeView (QtQuick.Controls 1.4)

I'm able to show the field i need using TableViewColumn and implementing roleNames() method

TableViewColumn {
           title: "isSub"
           role: "sub"
           width: 100
       }

QHash<int, QByteArray> OpcUaModel::roleNames() const
{
        QHash<int, QByteArray> roles;
        roles[NodeSubActive] = "sub";
        return roles;
}

this works as expected, it shows the value of my sub variable.

My problem is that I don't know how to access to that variable from somwhere else like :

itemDelegate: Text {
           text: styleData.value
           color: myUaModel.sub   ? "blue" : "red"
          // or   color: styleData.sub  ? "blue" : "red"
       }

Can someone tell how this should be done please ?

Thank you

[raven-worx]

@LeLev
a variable is attached to each item delegate instance according to the item/row displayed
so simply use the roleName in the delegate context

Edit: ah, i misread. you are using controls1

as a workaround you can add a custom invokable method which gives you the role value for "styleData.row". This custom invokable method, simply calls data() with the itemrole value taken from roleNames()

[ODБOï]

hi, thank you very much for your answer
@raven-worx said in Accessing QAbstractItemModel fields in QML:

as a workaround you can add a custom invokable method which gives you the role value for "styleData.row". This custom invokable method, simply calls data() with the itemrole value taken from roleNames()

I was trying to do that but i was wondering if things will get refreshed correctly, I will try and let you know.

[ODБOï]

@raven-worx hi
I am trying to write the q_invokable method you suggested to me but i have lots of troubles, this is what i try

itemDelegate: Text {
     text: styleData.value 
     color: myUaModel.getSubActiveByIndex(styleData.row,styleData.column) ? "green" : "blue"
}

  Q_INVOKABLE bool getSubActiveByIndex(int r, int c){ 
        qDebug() << "r : " << r << ";" << "c : " << c;
        QModelIndex idx = QAbstractItemModel::createIndex(r,c);
        qDebug() << "ModelIndex : " << idx;
        if(idx.isValid()){
            auto item = static_cast<TreeItem *>(idx.internalPointer());
            qDebug()  << item; // always outputs QObject(0x0)
        }else{
            qDebug()<< "Bad qModelIndex";
        }

i get this output when i show the tree view in QML, this are the 3 children of my root node, but it looks like i already have an issue here because qDebug() << item; shows QObject(0x0)

r :  0 ; c :  0
ModelIndex :  QModelIndex(0,0,0x0,OpcUaModel(0x127b460))
QObject(0x0)
r :  0 ; c :  1
ModelIndex :  QModelIndex(0,1,0x0,OpcUaModel(0x127b460))
QObject(0x0)
r :  0 ; c :  2
ModelIndex :  QModelIndex(0,2,0x0,OpcUaModel(0x127b460))
QObject(0x0)

Then if i access items attributes or data() method, obviously my app crashes, do you see what I did wrong ?

To me it looks like i'm doing something wrong about QModelIndex creation, because if i pass the QModelIndex directly from qml to c++ like this :

TreeView{
    onDoubleClicked: myUaModel.subscribe(index)
}
//c++
Q_INVOKABLE void subscribe(QModelIndex ind ){
       auto item = static_cast<TreeItem *>(ind.internalPointer());
// ...
}

this way i can construct and interact with the TreeItems.
The probleme is that index is not avalable in the itemDelegate, thats why i pass styleData.row and styleData.column

color : myUaModel.getSubActiveByIndex(styleData.row,styleData.column) ? "green" : "red"

and try construct the QModelIndex in cpp

Q_INVOKABLE bool getSubActiveByIndex(int r, int c){
  QModelIndex idx = QAbstractItemModel::createIndex(r,c); 

TreeItem and the model class come from this example : https://doc.qt.io/QtOPCUA/qtopcua-opcuaviewer-example.html (i'm just trying to change the view from QtreeView to QML TreeView. My first post about this )

[ODБOï]

@LeLev said in Accessing QAbstractItemModel fields in QML:

To me it looks like i'm doing something wrong about QModelIndex creation, because if i pass the QModelIndex directly from qml to c++ like this :

indeed this was the problem, instead of passing styleData.row and styleData.column to my Q_Invokable method i can pass
styleData.index

itemDelegate: Text {
 color:  myUaModel.getSubActiveByIndex(styleData.index) ? "green" : "blue"
}

Q_INVOKABLE bool getSubActiveByIndex(QModelIndex ind){
        bool isSub = false;
        if(!ind.isValid()) return isSub;

        auto item = static_cast<TreeItem *>(ind.internalPointer());
        isSub = item->data(7).toBool();
        return isSub;
    }