Drag and Drop QStandardItemModel in QML

Solayer

Hi, i'm a newbie.
I want to drag and drop a item in Tree View in qml. I create item by QStandardItem::appendRow. But i don't understand how to drag and drop a item.
This is my code:
treeviewmodel.h

class TreeViewModel : public QStandardItemModel
{
    Q_OBJECT
public:
    explicit TreeViewModel(QObject *parent = nullptr);

    virtual ~TreeViewModel() = default;

    enum MyRoles {
        My_Role_ID = 1000,
        My_Role_Address,
        My_Role_Name,
        My_Role_Object,
        My_Role_Property,
        My_Role_Value
    };

    Qt::DropActions supportedDropActions() const override;

    Qt::DropActions supportedDragActions() const override;

    virtual Qt::ItemFlags flags(const QModelIndex &index) const override;

    QStringList mimeTypes() const override;

    QMimeData * mimeData(const QModelIndexList &indexes) const override;

    bool dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent) override;

    QHash<int, QByteArray> roleNames() const override;

public slots:

     void newParent(QString name);

private:
     QHash<int, QByteArray> m_roleNameMapping;
};

treeviewmodel.c

#include "treeviewmodel.h"
#include <QStandardItem>

TreeViewModel::TreeViewModel(QObject *parent)
    : QStandardItemModel(parent)
{
    m_roleNameMapping[My_Role_Name] = "name_role";
    m_roleNameMapping[My_Role_Property] = "property_role";
    m_roleNameMapping[My_Role_Value] = "value_role";
    this->mimeTypes();
    this->supportedDragActions();
    this->supportedDropActions();
}
Qt::DropActions TreeViewModel::supportedDropActions() const
{
    return Qt::CopyAction | Qt::MoveAction;
}

Qt::DropActions TreeViewModel::supportedDragActions() const
{
    return Qt::CopyAction | Qt::MoveAction;
}

Qt::ItemFlags TreeViewModel::flags(const QModelIndex &index) const
{
    if (!index.isValid()){
        return Qt::ItemIsDropEnabled | Qt::ItemIsDragEnabled;
    }

    return Qt::ItemIsDropEnabled | Qt::ItemIsDragEnabled | QAbstractItemModel::flags(index);
}

QStringList TreeViewModel::mimeTypes() const
{
    QStringList types;
    types << "application/vnd.text.list";
    return types;
}

QMimeData *TreeViewModel::mimeData(const QModelIndexList &indexes) const
{
    QMimeData *mimeData = new QMimeData();
    QByteArray encodedData;

    QDataStream stream(&encodedData, QIODevice::WriteOnly);

    foreach (const QModelIndex &index, indexes) {
        if (index.isValid()) {
            QString text = data(index, Qt::DisplayRole).toString();
            stream << text;
        }
    }

    mimeData->setData("application/vnd.text.list", encodedData);
    return mimeData;
}

bool TreeViewModel::dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent)
{
    if(action == Qt::IgnoreAction){
        return true;
    }
    if(!data->hasFormat("application/vnd.text.list")){
        return false;
    }
    if(column >= columnCount(parent)){
        return false;
    }
    int beginRow;
    if (row != -1){
         beginRow = row;
    }else if(parent.isValid()){
         beginRow = parent.row();
    } else{
         beginRow = rowCount(parent);
    }
    QByteArray encodedData = data->data("application/vnd.text.list");
    QDataStream stream(&encodedData,QIODevice::ReadOnly);
    QStringList newItems;
    int rows = 0;
    while(!stream.atEnd()){
        QString text;
        stream >> text;
        newItems << text;
         ++rows;
    }
    insertRows(beginRow, rows, parent);
    foreach (QString text, newItems) {
        QModelIndex idx = index(beginRow, 0, parent);
        setData(idx, text);
        beginRow++;
    }
    return true;
}
void TreeViewModel::newParent(QString name)
{
    QStandardItem *parent = new QStandardItem(name);
    parent->setFlags(parent->flags() & ~Qt::ItemIsDragEnabled);
    parent->setData(name,My_Role_Name);
    this->appendRow(parent);
}
QHash<int, QByteArray> TreeViewModel::roleNames() const
{
    return m_roleNameMapping;
}

main.cpp

TreeViewModel *list_divice = new TreeViewModel;
engine.rootContext()->setContextProperty("listdevice",list_divice);

qml file

C1.TreeView{
        id: listLeftSide
        anchors.fill: parent
        model: listdevice
        selectionMode: SelectionMode.SingleSelection
        onDoubleClicked: {
            let currentDevice = listdevice.data(listLeftSide.currentIndex,1000)
            console.log(currentDevice)
          }
        C1.TableViewColumn{
            role: "name_role"
            title: "Device"
            width: leftSide.width

        }

Sorry about my stupid question. I have sreached a lot but none of them not working. What's my wrong. Can someone give me a example. Thank you very much.
Sorry, my english's very bad

WaterStar

Me too, This is my problem, Does anybody help us???

Solayer

can someone help me, pls