QSortFilterProxyModel with QStandardItemModel after appendRow are not working - qt

Question

Here what I have got:
a QTreeView widget (*);
Source model MainModel inherits from QStandardItemModel. No virtual data() const method reimplemented;
Proxy MainFilterProxyModel inherits from QSortFilterProxyModel;
The tree:
[PERIOD 1]
[CHILD 1]
[CHILD 2]
[SUBCHILD 2.1]
...
[CHILD N]
[PERIOD 2]
...
[PERIOD N]
So the main problem comes when I'm trying to add a CHILD-row like (**) code do. Filter proxy model, after document was added to source model, does not know about new row and didn't show it on the tree.
I'm sure that proxy didn't get signal from QStandardItemModel when appendRow method do his job, so proxy can't filter new row, and didn't make it visible.
Any help?
Thanks.
PS: If I turn off proxy, everything appended just fine. But the problem is not in proxy. Proxy just doesn't get the signal about new row appended to the main source model...
(*) Here is QTreeView:
MainView::MainView( QWidget* parent /* = 0 */ ) : QTreeView( parent )
{
if( !model_ )
{
model_ = new MainModel( this );
}
if( !proxy_ )
{
proxy_ = new MainFilterProxyModel( this );
proxy_->setDynamicSortFilter( true );
proxy_->setSourceModel( model_ );
setModel( proxy_ );
}
}
(**) Here is my append function:
void MainModel::addRow( const DocumentPtr& document, QStandardItem* parentItem )
{
assert( document );
QList< QStandardItem* > items;
items << ( new QStandardItem );
items << ( new QStandardItem );
items << ( new QStandardItem );
items << ( new QStandardItem );
items << ( new QStandardItem );
items << ( new QStandardItem );
items << ( new QStandardItem );
updateRow( document, items );
if( !parentItem )
{
BOOST_FOREACH( const TimePeriod& period, TimePeriod::all() )
{
if( period.contains( QDateTime::fromTime_t( document->creationDate() ) ) )
{
QStandardItem* periodItem = itemByPeriod( period );
Q_ASSERT( periodItem );
periodItem->appendRow( items );
break;
}
}
}
else
{
parentItem->appendRow( items );
}
}

Answer 1

The base class for modeling is QAbstractItemModel. It is better to use the methods of the abstract class to do what you want. QStandardItemModel is a simple implementation of the abstract methods of QAbstractItemModel and most of the QStandardItemModel new methods are used by the reimplemented abstract functions. Here is a code to add item and subitem using the abstract class methods:
QAbstractItemModel * pModel = new QStandardItemModel(parent);
int nRows = pModel->rowCount();
pModel->insertRow(nRows); // this will emit rowsAboutToBeInserted() and rowsInserted() signals
pModel->insertColumn(0); // this will emit columnsAboutToBeInserted() and columnsInserted() signals
const QModelIndex indexFirstItem = pModel->index(nRows, 0);
pModel->setData(indexFirstItem, "Item text"); // this will emit dataChanged() signal
int nChildRows = pModel->rowCount(indexFirstItem);
pModel->insertRow(nChildRows, indexFirstItem); // this will emit rowsInserted()
pModel->insertColumn(0, indexFirstItem); // we also need to do this for the item's children
const QModelIndex indexChild = pModel->index(nChildRows, 0, indexFirstItem);
pModel->setData(indexChild, "Child item text");
If we try to do the same using QStandardItemModel methods it will look like:
QStandardItemModel *pModel = new QStandardItemModel(parent);
QStandardItem *pItem = new QStandardItem("Item text");
pItem->appendRow(new QStandardItem); // pItem is not yet added to pModel and rowsInserted won't be emitted
pModel->appendRow(pItem); // this will probably emit rowsInserted() signal but since we set tha text of the item when creating the pItem the dataChanged() signal won't be emitted.
So if you do pItem->appendRow() to add sub items and if the pItem is not yet added to the model, you will probably not get the rowsInserted() signal and therefore the proxy model won't be notified. From my experience the first method works better and is more robust though you need to write a couple of extra lines. Working directly with QStandardItemModel methods will often end with missing signals or other headaches. All you need to look is the QAbstractItemModel and QModelIndex documentations.