[qt4,win,g++] model/view programming: selection, internal pointer wrong ?!

[jh]

hi,
i get a selection model from a treeview and connect signal
selectionChanged to the following method:

void
Container_Widget::selectionChanged(const QItemSelection& selected, 
				   const QItemSelection& deselected)
{
 
  printf("<Container_Widget::selection changed()>\n");
  fflush(stdout);
 
  QModelIndexList indexlist = selected.indexes();
  QListIterator<QModelIndex> it(indexlist);
 
  while(it.hasNext()) {
 
    QModelIndex modelindex = it.next();
 
    if(!modelindex.isValid()) {
      printf("Container_Widget::selectionChanged() : model index not valid \n");
      fflush(stdout);
      continue;
    }
 
    printf("Container_Widget::selectionChanged() : row = %d, col = %d \n",
	   modelindex.row(), modelindex.column() );
    fflush(stdout);
 
    Container_ModelItem* item
      = static_cast<Container_ModelItem*>(modelindex.internalPointer());
 
    ... call some method of item -> segfault !!
 
  }
 
  printf("</Container_Widget::selection changed()>\n");
  fflush(stdout);
 
}

void
Container_Widget::selectionChanged(const QItemSelection& selected, 
				   const QItemSelection& deselected)
{

  printf("<Container_Widget::selection changed()>\n");
  fflush(stdout);
  
  QModelIndexList indexlist = selected.indexes();
  QListIterator<QModelIndex> it(indexlist);

  while(it.hasNext()) {

    QModelIndex modelindex = it.next();

    if(!modelindex.isValid()) {
      printf("Container_Widget::selectionChanged() : model index not valid \n");
      fflush(stdout);
      continue;
    }
       
    printf("Container_Widget::selectionChanged() : row = %d, col = %d \n",
	   modelindex.row(), modelindex.column() );
    fflush(stdout);
   
    Container_ModelItem* item
      = static_cast<Container_ModelItem*>(modelindex.internalPointer());

    ... call some method of item -> segfault !!

  }
  
  printf("</Container_Widget::selection changed()>\n");
  fflush(stdout);

}

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the problem is that the internal pointer of the model index
cannot be of class Container_ModelItem,
since if i call a method of this class the program crashes.
i checke already all methods of the model which return a QModelIndex,
i could'nt find a mistake there.
where is the mistake?

bets regards,
jh

[wysota]

First of all use dynamic_cast instead of static one. And second of all, it's not possible to help you without seeing the source of the model, at least its index() method.

[jh]

i already found the problem. i used a sorting proxy model which was
invalid.

thanx.

jh