Selections in a TableView with a QItemSelectionModel

[xelag]

Hello,

I have a problem with a Model-View-Controler.

I can't get the index of the selected items in my view. It seems that there are no connection between my model and my selection model

Here is my MVC,

• model : QAbstractTableModel
• view : QTableView Proxy
• proxy : QSortFilterProxyModel
• delegate : QAbstractItemDelegate
• selection model : QItemSelectionModel

My view selection setting is set as :

setSelectionMode (QAbstractItemView::ExtendedSelection);
setSelectionBehavior (QAbstractItemView::SelectRows);

setSelectionMode (QAbstractItemView::ExtendedSelection);
setSelectionBehavior (QAbstractItemView::SelectRows);

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In my model, each data gets a Qt::ItemFlags as Qt::ItemIsSelectable :

Qt::ItemFlags DSTableModel::flags(const QModelIndex &_index) const
{
    if (!_index.isValid())
    {
        return QAbstractItemModel::flags(_index) | Qt::ItemIsEnabled;
    }
    return QAbstractItemModel::flags(_index) | Qt::ItemIsEditable | Qt::ItemIsSelectable;
}

Qt::ItemFlags DSTableModel::flags(const QModelIndex &_index) const
{
    if (!_index.isValid())
    {
        return QAbstractItemModel::flags(_index) | Qt::ItemIsEnabled;
    }
    return QAbstractItemModel::flags(_index) | Qt::ItemIsEditable | Qt::ItemIsSelectable;
}

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In my main program, i use this slot function to delete the selected rows in the view:

void DSMainWindow::deleteDataSlot()
{
    //Get the QModelIndex list of items selected in the view
    QModelIndexList tmpModelIndexList = selectionModel->selectedIndexes();
 
    if(tmpModelIndexList.count()==0)
    {
        //---> Always comes here because no items have been detected selected, despite 
        //the fact that the user has selected rows for real in the view !!!!!!!!!!!!!!!!!!
       QMessageBox::information(this, tr("DataSearch delete data"),
                    tr("No data is selected"),
                    QMessageBox::Ok,0,0);
        return;
    }
    else{}
 
    int tmpMsgRet = QMessageBox::question(this, tr("DataSearch delete data"),
                    tr("Are you sure you want to delete the selected data?") +
                    tr("\nThe data deleted will be lost."),
                    QMessageBox::Yes,QMessageBox::No | QMessageBox::Default,0);
 
    if (tmpMsgRet == QMessageBox::Yes)
    {
        //list used to store the row already deleted (multiple QModelIndex for a row
        QList<int> tmpRowRemoved;
 
        int currentRow;
 
 
        for(int i=0; i<tmpModelIndexList.count();i++)
        {
            currentRow = tmpModelIndexList.at(i).row();
 
            //test if the row has not been deleted yet
            if(tmpRowRemoved.indexOf(currentRow) > 0)
            {
                //delete the row in the model
                tableModel->removeRows(currentRow,1,tableView->currentIndex());
                tmpRowRemoved.append(currentRow);
            }
        }
    }
    else{}
}

void DSMainWindow::deleteDataSlot()
{
    //Get the QModelIndex list of items selected in the view
    QModelIndexList tmpModelIndexList = selectionModel->selectedIndexes();

    if(tmpModelIndexList.count()==0)
    {
        //---> Always comes here because no items have been detected selected, despite 
        //the fact that the user has selected rows for real in the view !!!!!!!!!!!!!!!!!!
       QMessageBox::information(this, tr("DataSearch delete data"),
                    tr("No data is selected"),
                    QMessageBox::Ok,0,0);
        return;
    }
    else{}
    
    int tmpMsgRet = QMessageBox::question(this, tr("DataSearch delete data"),
                    tr("Are you sure you want to delete the selected data?") +
                    tr("\nThe data deleted will be lost."),
                    QMessageBox::Yes,QMessageBox::No | QMessageBox::Default,0);

    if (tmpMsgRet == QMessageBox::Yes)
    {
        //list used to store the row already deleted (multiple QModelIndex for a row
        QList<int> tmpRowRemoved;
        
        int currentRow;
        
        
        for(int i=0; i<tmpModelIndexList.count();i++)
        {
            currentRow = tmpModelIndexList.at(i).row();
            
            //test if the row has not been deleted yet
            if(tmpRowRemoved.indexOf(currentRow) > 0)
            {
                //delete the row in the model
                tableModel->removeRows(currentRow,1,tableView->currentIndex());
                tmpRowRemoved.append(currentRow);
            }
        }
    }
    else{}
}

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Can the delegate or the proxy cause a problem? Is there something to add in the model?

Please help. I'm searching for a long time where it bugs... But those MVCs are quite tough to debug...

Thx,
Xelag

[wysota]

Why does the "selectionModel" variable hold? How and when did you initialise it?

[xelag]

I don't understand your 1st question?

Why does the "selectionModel" variable hold? How and when did you initialise it?

2nd question :

How and when did you initialise it?

I initialise it in the main program :

int main(int argc, char *argv[])
{
    DSTableModel *tableModel = new DSTableModel();
    DSSortFilterProxy *sortFilterProxy = new DSSortFilterProxy();
    DSTableView *tableView = new DSTableView(0);
    DSTableDelegate *tableDelegate = new DSTableDelegate();
    //here
    QItemSelectionModel *selectionModel = new QItemSelectionModel(tableModel);
 
//After that, I create my main window; I pass through the constructor the different adress 
//of MVC elements :
     DSMainWindow *mainWin = new DSMainWindow(tableModel,
                                             sortFilterProxy,
                                             tableView,
                                             tableDelegate,
                                             selectionModel);
}

int main(int argc, char *argv[])
{
    DSTableModel *tableModel = new DSTableModel();
    DSSortFilterProxy *sortFilterProxy = new DSSortFilterProxy();
    DSTableView *tableView = new DSTableView(0);
    DSTableDelegate *tableDelegate = new DSTableDelegate();
    //here
    QItemSelectionModel *selectionModel = new QItemSelectionModel(tableModel);
    
//After that, I create my main window; I pass through the constructor the different adress 
//of MVC elements :
     DSMainWindow *mainWin = new DSMainWindow(tableModel,
                                             sortFilterProxy,
                                             tableView,
                                             tableDelegate,
                                             selectionModel);
}

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In the main window, each MVC element is a property class initialise in constructor with arguments writtent above.

DSMainWindow::DSMainWindow(DSTableModel *_tableModel,
                           DSSortFilterProxy *_sortFilterProxy,
                           DSTableView * _tableView,
                           DSTableDelegate *_tableDelegate,
                           QItemSelectionModel *_selectionModel,
                           QWidget *parent,
                           Qt::WFlags flags)
                           : QMainWindow(parent, flags)
{
 //Initialisation of properties
    tableModel = _tableModel;;
    sortFilterProxy = _sortFilterProxy;
    tableView = _tableView;
    tableDelegate = _tableDelegate;
    selectionModel = _selectionModel;
 
 //Initialisation of the model structure
    sortFilterProxy->setSourceModel(tableModel);
    tableView->setModel(sortFilterProxy);
    tableView->setItemDelegate(tableDelegate);
    tableView->setSelectionModel(selectionModel);
//...

DSMainWindow::DSMainWindow(DSTableModel *_tableModel,
                           DSSortFilterProxy *_sortFilterProxy,
                           DSTableView * _tableView,
                           DSTableDelegate *_tableDelegate,
                           QItemSelectionModel *_selectionModel,
                           QWidget *parent,
                           Qt::WFlags flags)
                           : QMainWindow(parent, flags)
{
 //Initialisation of properties
    tableModel = _tableModel;;
    sortFilterProxy = _sortFilterProxy;
    tableView = _tableView;
    tableDelegate = _tableDelegate;
    selectionModel = _selectionModel;

 //Initialisation of the model structure
    sortFilterProxy->setSourceModel(tableModel);
    tableView->setModel(sortFilterProxy);
    tableView->setItemDelegate(tableDelegate);
    tableView->setSelectionModel(selectionModel);
//...

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[wysota]

I don't understand your 1st question?

Sorry, should be "what" instead of "why"

2nd question :

I initialise it in the main program :

int main(int argc, char *argv[])
{
// ...
    DSTableView *tableView = new DSTableView(0);
// ...
    QItemSelectionModel *selectionModel = new QItemSelectionModel(tableModel);

int main(int argc, char *argv[])
{
// ...
    DSTableView *tableView = new DSTableView(0);
// ...
    QItemSelectionModel *selectionModel = new QItemSelectionModel(tableModel);

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//Initialisation of the model structure
    sortFilterProxy->setSourceModel(tableModel);
    tableView->setModel(sortFilterProxy);
//...
    tableView->setSelectionModel(selectionModel);
//...

//Initialisation of the model structure
    sortFilterProxy->setSourceModel(tableModel);
    tableView->setModel(sortFilterProxy);
//...
    tableView->setSelectionModel(selectionModel);
//...

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How about:

QTableView *view = new QTableView(...);
tableView->setModel(sortFilterProxy);
QItemSelectionModel = tableView->selectionModel(); // <-- use this one

QTableView *view = new QTableView(...);
tableView->setModel(sortFilterProxy);
QItemSelectionModel = tableView->selectionModel(); // <-- use this one

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You don't need to create your own selection model, the view already has one. The selection model will tell you about selections of the model which is set in the view - in your case the proxy model, so you need to map indexes to the source model using QAbstractProxyModel::mapToSource() if you want to operate on the model directly. But it is possible that you can do most operations by operating on the proxy instead - then you don't need to map indexes.