QPersistentModelIndex problem

[laugusti]

Hi all,

Here is my problem ... I have a widget containing 4 tree views connected to the same model. I store QModelIndex to be able to restore expanded items when I switch from a tree view to another.
In order to do it, I want to use QPersistentModelIndex because if I delete a QModelIndex from my model, the QPersistentModelIndex would become invalid. At least, it's what I understood from the documentation.

Here is my code:

/**
 * List of expanded items.
 */
QModelIndexList m_expandedItemList;
 
//================================================================
void QResourceTree::addExpandedItem(const QModelIndex& index)
{
	QResourceProxyModel * proxyModel = (QResourceProxyModel*)model();
	QModelIndex sourceIndex = proxyModel->mapToSource(index);
	m_expandedItemList.append(QPersistentModelIndex(sourceIndex));
}
 
//================================================================
void QResourceTree::restoreExpandedItems() {
 
	if (!m_expandedItemList.empty()) {
 
		/* Restore expanded items */
		QModelIndexList::iterator it;
		for (it=m_expandedItemList.begin() ; it != m_expandedItemList.end(); it++) {
 
			if ((*it).isValid()) {
 
				QResourceProxyModel * proxyModel = (QResourceProxyModel*)model();
				QModelIndex index = proxyModel->mapFromSource(*it);
 
				if (index.isValid() && !isExpanded(index)) {
					this->expand(index);
				}
			}
		}
	}
}

/**
 * List of expanded items.
 */
QModelIndexList m_expandedItemList;

//================================================================
void QResourceTree::addExpandedItem(const QModelIndex& index)
{
	QResourceProxyModel * proxyModel = (QResourceProxyModel*)model();
	QModelIndex sourceIndex = proxyModel->mapToSource(index);
	m_expandedItemList.append(QPersistentModelIndex(sourceIndex));
}

//================================================================
void QResourceTree::restoreExpandedItems() {

	if (!m_expandedItemList.empty()) {

		/* Restore expanded items */
		QModelIndexList::iterator it;
		for (it=m_expandedItemList.begin() ; it != m_expandedItemList.end(); it++) {

			if ((*it).isValid()) {

				QResourceProxyModel * proxyModel = (QResourceProxyModel*)model();
				QModelIndex index = proxyModel->mapFromSource(*it);

				if (index.isValid() && !isExpanded(index)) {
					this->expand(index);
				}
			}
		}
	}
}

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Code for deletion:

// Is it the right order?
1/ m_root->removeChildren(index.row());
2/ changePersistentIndex(index, QModelIndex());

// Is it the right order?
1/ m_root->removeChildren(index.row());
2/ changePersistentIndex(index, QModelIndex());

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Anytime I delete an expanded item, when I restore the expanded item list, it crashes because my QPersistentModelIndex is still valid.
How do we get a persistent index from a model index? I thought it would be by using the constructor, maybe I am wrong?
Anybody has an example showing how to use QPersistentModelIndex?


Thanks,
Lionel

[caduel]

you must not store the perstistent model indexes in a QModelIndexList; use

QList<QPersistentModelIndex>

QList<QPersistentModelIndex>

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instead

HTH

[laugusti]

Thank you Caduel,

It works perfectly now!

Regards,
Lionel