What error causes the Treeview data model QAbstractItemModel replacement method to be unavailable?

[mirro]

bool TreeModel::replaceRows(int row, int count, QModelIndex parent)
{
    if (parent.isValid())
    {
        QModelIndex idxRemove = parent.child(row, 0);
        TreeItem* fiModify    = static_cast<TreeItem*>(idxRemove.internalPointer());
        if (fiModify.child(0, 0).isValid())
        {
            beginRemoveRows(QModelIndex(),row,0);
            removeRows(0, 0, index(row, 0, QModelIndex()));
            endRemoveRows();
            QList<QVariant> TestItem;
            TestItem.append("TestItem");
            TreeItem* TestItem_Item = new TreeItem(TestItem);
            rootItem->replace(row,TestItem_Item);
            dataChanged(index(row,0),index(row,0),{NameEnum});
            return true;
        }
    }
    else
    {
        beginRemoveRows(QModelIndex(), row, 0);
        removeRows(row, 0, index(row, 0, QModelIndex()));
        endRemoveRows();
        QList<QVariant> TestItem;
        TestItem.append("TestItem");
        TreeItem* TestItem_Item = new TreeItem(TestItem);
        rootItem->replace(row,TestItem_Item);
        dataChanged(index(row,0),index(row,0),{NameEnum});
        return true;
    }
    return false;
}

[JonB]

@mirro
Your question reads

What error causes the Treeview data model QAbstractItemModel replacement method to be unavailable?

How does this relate to the code you show?

[mirro]

@JonB How are dataChanged signals used?Why can't the data be completely replaced.

The data method is called once when I use the dataChanged signal.

The data method is called three when I use the beginInsertRows(QModelIndex(), row, row) signal

class ReaderModel :  public QAbstractListModel
{
    Q_OBJECT
    Q_PROPERTY(Reader* me READ me WRITE setMe NOTIFY meChanged)
public:
    enum ReaderRole {
        IdRole = Qt::DisplayRole, //0
        PasswordRole = Qt::UserRole,
        RecordRole
    };
    Q_ENUM(ReaderRole)

    ReaderModel(QObject *parent = nullptr){Q_UNUSED(parent);}

    int rowCount(const QModelIndex & = QModelIndex()) const;
    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
    QHash<int, QByteArray> roleNames() const;

    Q_INVOKABLE void replace(int row, const QString &id,
                         const QString &password);
private:
    QList<Reader*> m_readers;
};

QVariant ReaderModel::data(const QModelIndex &index, int role) const
{
    if(index.row() < rowCount())
        switch(role){
        case IdRole: return m_readers.at(index.row())->id();
        case PasswordRole: return m_readers.at(index.row())->password();
        case RecordRole: return m_readers.at(index.row())->record();
        default: return QVariant();
        }
    return QVariant();
}

void ReaderModel::replace(int row, const QString &id, const QString &password)
{
    if (row < 0 || row >= m_readers.count())
        return;
    Reader *r = new Reader(id, password == ""? m_readers[row]->password() : password);
    m_readers.replace(row, r);
    dataChanged(index(row, 0), index(row, 0), { IdRole,PasswordRole});
}

[JonB]

@mirro
Again, I'm sorry, but I just don't know what your question is, what behaviour you expect vs what happens, etc.? Perhaps someone else will understand better than I.

Just one observation: you seem to be implementing a QAbstractListModel which is editable, so just as you have overridden the data() method I would expect to see you overriding the setData() method.

[fcarney]

Why are you removing a row? You end up overwriting the next row down? Either remove and add a new row. Or overwrite the existing row. You cannot do both.

[mirro]

@JonB When I select a node, How do I traverse the children and sibling node in QML?
Do I need to add methods to the QAbstractItemModel in C++ ?

import QtQuick 2.2
import QtQuick.Controls 1.4
import QtQml.Models 2.2

ApplicationWindow {
    visible: true
    width: 640
    height: 480
    title: qsTr("File System")

    ItemSelectionModel {
        id: sel
        model: fileSystemModel
        onSelectionChanged: {
            console.log("selected", selected)
            console.log("deselected", deselected)
        }
        onCurrentChanged: console.log("current", current)
    }
    TreeView {
        id: view
        anchors.fill: parent
        anchors.margins: 2 * 12
        model: fileSystemModel
        selection: sel
        onCurrentIndexChanged: console.log("current index", currentIndex)

        itemDelegate: Rectangle {
            color: ( styleData.row % 2 == 0 ) ? "white" : "lightblue"
            height: 40
            Text {
                anchors.verticalCenter: parent.verticalCenter
                anchors.left: parent.left
                text: styleData.value 
            }
        }
        TableViewColumn {
            title: "Title"
            role: "name"
            resizable: true
        }
        TableViewColumn {
            title: "Summary"
            role: "summary"
            width: view.width/2
        }
        onClicked: console.log("clicked the index is ?", index)
        onDoubleClicked: isExpanded(index) ? collapse(index) : expand(index)
    }
}

[mirro]

@fcarney

HI~What method can I use to traverse the children under the selected node in QML?
Do I need to add methods to the QAbstractItemModel in C++ ?

MouseArea{
    OnPressed:{
             //...
             if(styleData.depth === 1)
             {
                      var curIndex = treeView.indexAt(mouse.x,mouse.y)
             }
    }
}