QTableView - Not Getting Selection Changed Signal

[jwomble]

I am fairly new to QT, and am having trouble understanding how the QTableView selection changed signal is handled. I have setup a window with an openGL widget and a QTableView. I have a data model class that is correctly populating the tableview, so I added a public slot to that class:

@class APartsTableModel : public QAbstractTableModel
{
public:
AVehicleModel *vehicle;
explicit APartsTableModel(QObject *parent = 0);

//MVC functions
int rowCount(const QModelIndex &parent) const;
int columnCount(const QModelIndex &paret) const;
QVariant data(const QModelIndex &index, int role) const;
QVariant headerData(int section, Qt::Orientation orientation, int role) const;

public slots:
void selectionChangedSlot(const QItemSelection &newSelection,
const QItemSelection &oldSelection);

};@

When I am ready to show the window with the table view, I allocate/initialize it like this:

@//create the display view
AStarModelView *displayWindow = new AStarModelView(this,
starModel->vehicle);

//create the datamodel for the table view
APartsTableModel *dataModel = new APartsTableModel(displayWindow);
dataModel->vehicle = starModel->vehicle;

//create selection model for table view
QItemSelectionModel *selModel = new QItemSelectionModel(dataModel);
displayWindow->materialsTable->setSelectionModel(selModel);

//setup model and signal
displayWindow->materialsTable->setModel(dataModel);

connect(selModel,
SIGNAL(selectionChanged(const QItemSelection &, const QItemSelection &)),
dataModel,
SLOT(selectionChangedSlot(const QItemSelection &, const QItemSelection &)));

//show the view
displayWindow->show();@

When I set a breakpoint in the implementation of the slot function, I never hit it. I've also tried not allocating a new QItemSelectionModel, but that didn't work either. I'm really not sure what I'm doing wrong here.

[daviddoria]

(There indeed is no selectionChanged signal of a QTableView, sorry)
-Do you really need the QItemSelectionModel? It doesn't sound like you are doing anything that complex. I think you want to connect the selectionChanged model of the VIEW to a slot.-

-connect(materialsTable,-
-SIGNAL(selectionChanged(const QItemSelection &, const QItemSelection &)),-
-dataModel,-
-SLOT(selectionChangedSlot(const QItemSelection &, const QItemSelection &)));-

I would also name your materialsTable materialsTableView or something like that - as to not confuse if the 'table' is a 'tableModel' or a 'tableView'.

[jwomble]

Does QTableView have a selectionChanged signal? I can't find it in the class reference.

[daviddoria]

Yep, it's in the superclass: http://developer.qt.nokia.com/doc/qt-4.8/qabstractitemview.html#signalSection

I was just complaining about that here :) : http://developer.qt.nokia.com/forums/viewthread/12604/

[jwomble]

I see a slot for selectionChanged() in QAbstractItemView, but not a signal.

[daviddoria]

Yikes - please ignore everything I've said so far - I was a bit confused (clearly).

Can you do this - handle the clicked() signal of the view (or the mouseRelease event if you're making bigger selections) and then use the view's selectedIndexes function to get the selection?

[daviddoria]

Gah - it is listed under public functions (http://developer.qt.nokia.com/doc/qt-4.8/qlistview.html#memberSection) even though it is protected (it even says protected right in the declaration in the doc!). Sorry, without subclassing the view this method won't do it for you.

[jwomble]

As far as I can tell, using the selectionModel is the correct way to do this, I just can't figure out what I'm doing wrong.

[jwomble]

What's the first thing you should check in QT when signals/slots don't seem to be working correctly? That your class has the Q_OBJECT macro in it. Added this to the APartsTable class definition, and now I'm hitting the breakpoint.

When does Friday get here?

[daviddoria]

Here is a compilable example:

http://programmingexamples.net/wiki/Qt/ModelView/ItemSelectionModel

[goetz]

The table implicitly has a selction model, get with <code>tableView->selectionModel()</code>, you don't need to create a new one.