QTreeView Drag and Drop with MyData

[baray98]

I have QTreeView which is connected to QStandardItemModel and I would like to support D&D in my view.

QStandardItem in my model contains my "MyData" as QVariant in Qt::UserRole like this

s_SqlListInfo info;
            //fill data
            [...]
 
            var.setValue(info);
            item->setData(var,Qt::UserRole);
            item->setData(info.queryName,Qt::DisplayRole);
            item->setData(QIcon(":/ListIcon.png"),Qt::DecorationRole);
            item->setFlags(item->flags()& ~Qt::ItemIsEditable);

s_SqlListInfo info;
            //fill data
            [...]

            var.setValue(info);
            item->setData(var,Qt::UserRole);
            item->setData(info.queryName,Qt::DisplayRole);
            item->setData(QIcon(":/ListIcon.png"),Qt::DecorationRole);
            item->setFlags(item->flags()& ~Qt::ItemIsEditable);

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I have declared myData like this

struct s_SqlListInfo
        {
           QVariant queryName;
           QVariant dataBaseName;
           QList <QString> reqTableList;
           QString sqlStatement;
        };
// Qt MetaType Declaration
Q_DECLARE_METATYPE(s_SqlListInfo)

struct s_SqlListInfo
        {
           QVariant queryName;
           QVariant dataBaseName;
           QList <QString> reqTableList;
           QString sqlStatement;
        };
// Qt MetaType Declaration
Q_DECLARE_METATYPE(s_SqlListInfo)

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Now, When I start dragging on my treeView it will assert with this message

ASSERT failure in QVariant::save "Invalid type to save", file kernel\qvariant.cpp line 1951

It seems like QVariant can not save my "MyData" that's why its asserting .... how can I fix this problem?

baray98

[numbat]

You can make your type savable by providing stream operators and calling qRegisterMetaTypeStreamOperators. It might be easier to just store the data individually, in Qt::UserRole + 1, etc, as Qt understands QVariant and QString automatically.

EDIT: This should do it:

QDataStream &operator<<(QDataStream &out, const s_SqlListInfo &myObj)
{
        out << myObj.queryName << myObj.dataBaseName << myObj.sqlStatement << myObj.reqTableList;
        return out;
}
 
QDataStream &operator>>(QDataStream &in, s_SqlListInfo &myObj)
{
        in >> myObj.queryName >> myObj.dataBaseName >> myObj.sqlStatement >> myObj.reqTableList;
        return in;
}
 
//Before use...
qRegisterMetaTypeStreamOperators<s_SqlListInfo>("s_SqlListInfo");

QDataStream &operator<<(QDataStream &out, const s_SqlListInfo &myObj)
{
        out << myObj.queryName << myObj.dataBaseName << myObj.sqlStatement << myObj.reqTableList;
        return out;
}

QDataStream &operator>>(QDataStream &in, s_SqlListInfo &myObj)
{
        in >> myObj.queryName >> myObj.dataBaseName >> myObj.sqlStatement >> myObj.reqTableList;
        return in;
}

//Before use...
qRegisterMetaTypeStreamOperators<s_SqlListInfo>("s_SqlListInfo");

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[baray98]

Thanks for the reply ...

But I am not sure where to add the above code in the project .. pardon my being newbie

should i put it before my declaration of my struct ?

baray98

[baray98]

QDataStream &operator<<(QDataStream &out, const DMUtils::s_SqlListInfo &myObj)
{
    out << myObj.queryName << myObj.dataBaseName << myObj.sqlStatement << myObj.reqTableList;
    return out;
}
 
QDataStream &operator>>(QDataStream &in, DMUtils::s_SqlListInfo &myObj)
{
    in >> myObj.queryName >> myObj.dataBaseName >> myObj.sqlStatement >> myObj.reqTableList;
    return in;
}
 
int main (int argc,char *argv[])
{
    QApplication app(argc,argv);
 
    qRegisterMetaTypeStreamOperators<DMUtils::s_SqlListInfo>("s_SqlListInfo");
    qRegisterMetaType<DMUtils::s_SqlListInfo>("s_SqlListInfo");
 
 
    DMMainWindow *mainWin = new DMMainWindow;
 
    mainWin->show();
 
    return app.exec();
}

QDataStream &operator<<(QDataStream &out, const DMUtils::s_SqlListInfo &myObj)
{
    out << myObj.queryName << myObj.dataBaseName << myObj.sqlStatement << myObj.reqTableList;
    return out;
}

QDataStream &operator>>(QDataStream &in, DMUtils::s_SqlListInfo &myObj)
{
    in >> myObj.queryName >> myObj.dataBaseName >> myObj.sqlStatement >> myObj.reqTableList;
    return in;
}

int main (int argc,char *argv[])
{
    QApplication app(argc,argv);

    qRegisterMetaTypeStreamOperators<DMUtils::s_SqlListInfo>("s_SqlListInfo");
    qRegisterMetaType<DMUtils::s_SqlListInfo>("s_SqlListInfo");


    DMMainWindow *mainWin = new DMMainWindow;

    mainWin->show();

    return app.exec();
}

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I did it like this and it will still crash!!!!!!!!!!!!!!!!!

[baray98]

i got it thanks buddy

the problem was this

qRegisterMetaTypeStreamOperators<DMUtils::s_SqlListInfo>("s_SqlListInfo");
    qRegisterMetaType<DMUtils::s_SqlListInfo>("s_SqlListInfo");
 
//change to 
 
qRegisterMetaTypeStreamOperators<DMUtils::s_SqlListInfo>("DMUtils::s_SqlListInfo");
    qRegisterMetaType<DMUtils::s_SqlListInfo>("DMUtils::s_SqlListInfo");

qRegisterMetaTypeStreamOperators<DMUtils::s_SqlListInfo>("s_SqlListInfo");
    qRegisterMetaType<DMUtils::s_SqlListInfo>("s_SqlListInfo");

//change to 

qRegisterMetaTypeStreamOperators<DMUtils::s_SqlListInfo>("DMUtils::s_SqlListInfo");
    qRegisterMetaType<DMUtils::s_SqlListInfo>("DMUtils::s_SqlListInfo");

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