So when I run the project, it loads 1000 rows and 10 columns of data to the _dataList in about 1-2 minutes. ( In the for loop I showed above)

It "cannot" take that long to execute those statements 1,000 times so I don't know what to say. Can only suggest you step through in debugger or set up a completely standalone program to do what you show and try there.

sorry, i didn't understand completely. Can you show an example from my code?

For

columnList.append(_model->data(_model->index(row,col)).toString());

if you have access to the "datalist" for your dedicated _model you are reading from, something like:

columnList.append(_the_model_datalist[col][row]);

to avoid going through _model->data() etc.

But now that you have said "minutes" to do the copying loop this should be irrelevant in comparison to that as-yet-unexplained slowness.

"Uzun bir süre" tanımlayın. "Çok az" zaman almalıdır.

Yes, I should have explained this part a little more. So when I run the project, it loads 1000 rows and 10 columns of data to the _dataList in about 1-2 minutes. ( In the for loop I showed above)
Don't you think it's a long time?

@JonB said in subclass queryModel:

If you want fastest, why do you go through your existing model at the _model->data(_model->index(row,col)) level?

what should I do ?

@JonB said in subclass queryModel:

If you have access to the underlying actual model/data (like your _dataList) you can read from that directly to avoid the model indexing overhead.

sorry, i didn't understand completely. Can you show an example from my code?

For example, a model with 1000 rows and 15 columns takes a long time to load into these vectors. Is there a more convenient or faster method for this?

Define "a long time". It should take "very little" time.

What here is taking much time? If you want fastest, why do you go through your existing model at the _model->data(_model->index(row,col)) level? If you have access to the underlying actual model/data (like your _dataList) you can read from that directly to avoid the model indexing overhead.

Nonetheless, I still would not expect your code to take long for "1000 rows and 15 columns".

myModel::myModel(QVector<QVector<QString> > *dataList,QVector<QString> headerDataList, QObject *parent,int rowcount,int colcount) :
    QAbstractTableModel{parent},_dataList(dataList),_headerDataList(headerDataList),_rowCount(rowcount),_colCount(colcount)
{




}

QVariant myModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid())
           return QVariant();
    if(index.row()>_dataList->at(0).count()-1 || index.column()>_dataList->count()-1)
        return QVariant();

    switch (role) {
    case Qt::DisplayRole:
        return _dataList->at(index.column()).at(index.row());

    case Qt::TextAlignmentRole:
        return Qt::AlignCenter;
    }
    return QVariant();

}



int myModel::rowCount(const QModelIndex &parent) const
{

    return _dataList->at(0).count();
}

int myModel::columnCount(const QModelIndex &parent) const
{

    return _dataList->count();
}

QVariant myModel::headerData(int section, Qt::Orientation orientation, int role) const
{
    if(orientation == Qt::Horizontal)
    {
        if(role == Qt::DisplayRole)
        {
            return _headerDataList.at(section);

        }
   }

    return QVariant();
}

But I'm asking for better speed.
For example, a model with 1000 rows and 15 columns takes a long time to load into these vectors. Is there a more convenient or faster method for this?

   _dataList = new QVector<QVector<QString> >;
   QVector<QString> _headerDataList;
   rowcount = _model->rowCount(); // this _model is another normal QSqlQueryModel.
   colcount = _model->columnCount();    
    
    for(int col = 0; col<colcount; col++)
       {  
           QVector<QString> columnList;
           for(int row = 0; row <rowcount ; row++)
           {
                columnList.append(_model->data(_model->index(row,col)).toString());
               
           }
           _dataList->append(columnList);
           _headerDataList.append(_model->headerData(col,Qt::Horizontal).toString());
       }

It's like taking the frame of an SUV to use it as a go-kart.

Use the right tool for your purpose and in your case QAbstractTableModel is the one that makes sense.

Hi,
First thing: why are you subclassing QSqlQueryModel when you want to show a custom data structure ? QAbstractTableModel would make more sense.

why do you suggest me to use QAbstractTableModel? what is the difference of this ?
Thanks, I'll look into the other things you said.

First thing: why are you subclassing QSqlQueryModel when you want to show a custom data structure ? QAbstractTableModel would make more sense.
Then, why not use something like QVector<QStringList> or even QVector<QVector<QString>> so you can more easily manipulate your data ? That would also allow you to have row and column count determined by the actual size of your 2D data rather than on fixed values.