incremental data fetching logic distorted when resetting the model

[user4592357]

i have implemented incremental data fetching for my tree view class.
at some point in time i need to clear the tree view content:

void TreeModel::resetModel()
{
	beginResetModel();
	getRootNode()->clear();
	endResetModel();
}

where:

void TreeNode::clear()
{
	qDeleteAll(m_children);
	m_children.clear();
}

however, my tree view is not cleared because after removing the children the root node still exists, and my canFetchMore() returns true and tree view is filled again.

i'm thinking of keeping a bool to determine whether or not to return true or false from canFetchMore() but i don't think that's a good solution. what else can i do?

by the way:

bool TreeModel::canFetchMore(const QModelIndex &parent) const
{
	if (!parent.isValid())
		return m_pRootNode->childCount() < m_pRootNode->actualChildCount();

	// get the node pointer
	auto node = static_cast<TreeNode *>(parent.internalPointer());
	return node->childCount() < node->actualChildCount();
}

[VRonin]

@user4592357 said in incremental data fetching logic distorted when resetting the model:

and my canFetchMore() returns true

This is the problem, nothing to do with the view.

I assume getRootNode() returns m_pRootNode? if so can you show the code for childCount and actualChildCount?

[user4592357]

@VRonin
yes that's right.

int TreeNode::childCount() const
{
	return m_children.size();
}

int TreeNode::actualChildCount() const
{
	return m_nActualChildCount;
}

and m_nActualChildCount is calculated once

[VRonin]

@user4592357 said in incremental data fetching logic distorted when resetting the model:

and m_nActualChildCount is calculated once

This needs to be recalculated if you reset the model