QListView drag error with qmetatype

[baray98]

I made a QListView which has a source of QStandardItemModel. I set the view to have the following settings

setMovement(QListView::Snap);
setResizeMode(QListView::Adjust);
setSpacing(5);
setViewMode(QListView::IconMode);

setMovement(QListView::Snap);
setResizeMode(QListView::Adjust);
setSpacing(5);
setViewMode(QListView::IconMode);

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My model's item is a QStandardItem and i added my "metatype registered value" at Qt::UserRole + 1. When I started draging the item in my view the whole things just crushes, but when i took my metatype registered value in my item it works fine. This will only happen when i drag those icons. I have accessed and displayed my custom data through the modelIndex and its fine no crushes.

below is how i declare my metatype value

struct s_SqlListInfo
        {
           QVariant queryName;
           QVariant dataBaseName;
           QList <QString> reqTableList;
           QString sqlStatement;
        };
 
// Qt MetaType Declaration
Q_DECLARE_METATYPE(s_SqlListInfo)
 
//spot where i added my value to the item
 
        QVariant myVal = hander->list().at(0); // hander->list() ,returns a QList of Qvariant   with my custom data
        if (myVal .canConvert<s_SqlListInfo>())
        {
            s_SqlListInfo info = myVal .value<s_SqlListInfo>();
 
            QStandardItem* item = new QStandardItem();
 
            item->setData(info.queryName.toString(),Qt::DisplayRole);
            item->setData(QIcon(":/ListIcon.png"),Qt::DecorationRole);
            item->setData(myVal ,Qt::UserRole+1);  // spot where i added my custom data
            item->setData(info.sqlStatement,Qt::ToolTipRole);
            item->setFlags(item->flags()& ~Qt::ItemIsEditable);
 
            m_userListModel->appendRow(item);
        }

struct s_SqlListInfo
        {
           QVariant queryName;
           QVariant dataBaseName;
           QList <QString> reqTableList;
           QString sqlStatement;
        };

// Qt MetaType Declaration
Q_DECLARE_METATYPE(s_SqlListInfo)

//spot where i added my value to the item

        QVariant myVal = hander->list().at(0); // hander->list() ,returns a QList of Qvariant   with my custom data
        if (myVal .canConvert<s_SqlListInfo>())
        {
            s_SqlListInfo info = myVal .value<s_SqlListInfo>();

            QStandardItem* item = new QStandardItem();

            item->setData(info.queryName.toString(),Qt::DisplayRole);
            item->setData(QIcon(":/ListIcon.png"),Qt::DecorationRole);
            item->setData(myVal ,Qt::UserRole+1);  // spot where i added my custom data
            item->setData(info.sqlStatement,Qt::ToolTipRole);
            item->setFlags(item->flags()& ~Qt::ItemIsEditable);

            m_userListModel->appendRow(item);
        }

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[wysota]

Can you provide a minimal compilable example reproducing the problem?

[baray98]

here we go

#include <QtGui>
 
struct myStruct
{
    QVariant queryName;
    QVariant dataBaseName;
    QList <QString> reqTableList;
    QString sqlStatement;
};
Q_DECLARE_METATYPE(myStruct)
 
int main (int argc,char *argv[])
{
    QApplication app(argc,argv);
    QListView *view = new QListView;
 
    view->setViewMode(QListView::IconMode);
 
    QStandardItemModel* model = new QStandardItemModel();
 
    for (int i=0; i < 5; ++i)
    {
        QStandardItem* item = new QStandardItem();
        item->setData(QString("Item %1").arg(i),Qt::DisplayRole);
       // custom data
        myStruct st;
        QVariant v;
        v.setValue(st);
        item->setData(v);
 
        model->appendRow(item);
    }
 
    view->setModel(model);
    view->show();
 
    return app.exec();
}

#include <QtGui>

struct myStruct
{
    QVariant queryName;
    QVariant dataBaseName;
    QList <QString> reqTableList;
    QString sqlStatement;
};
Q_DECLARE_METATYPE(myStruct)

int main (int argc,char *argv[])
{
    QApplication app(argc,argv);
    QListView *view = new QListView;

    view->setViewMode(QListView::IconMode);

    QStandardItemModel* model = new QStandardItemModel();

    for (int i=0; i < 5; ++i)
    {
        QStandardItem* item = new QStandardItem();
        item->setData(QString("Item %1").arg(i),Qt::DisplayRole);
       // custom data
        myStruct st;
        QVariant v;
        v.setValue(st);
        item->setData(v);

        model->appendRow(item);
    }

    view->setModel(model);
    view->show();

    return app.exec();
}

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[wysota]

It works fine for me on Qt 4.5.2.

[baray98]

I am still @ 4.5.1 I did not realize they have 4.5.2 already....

[wysota]

I don't think this is a matter of different releases.

[baray98]

When you said it work.. did you try dragging an item somewher else?

[baray98]

I think it's the Q_ASSERT_X thats doing it(crashing) . When it crash it gave an ASSERT Error on line 1951 in qvariant.cpp . I tried recompiling it on release mode and it work.

Why would qvariant assert something legal , maybe a warning would be fine not QUIT.. or maybe i am using qvariant the wrong way..

[wysota]

When you said it work.. did you try dragging an item somewher else?

Somewhere else meaning where?