QAbstractItemModel to wrap multiple QStandardItemModels throws ASSERT in QTreeView

Hi,

I'm trying to subclass QAbstractItemModel so I can add multiple QStandardItemModels and show them in a single QTreeView. Something like:

Code:

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CombinedTreeModel * combined = new CombinedTreeModel (0);
combined ->addStandardItemModel(model1);
combined ->addStandardItemModel(model2);
combined ->addStandardItemModel(model3);

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model1, 2, and 3 are QStandardItemModels and the addStandardItemModel(...) adds the top node of each model to an internal root node in CombinedTreeModel
I used the "simpletreemodel" as an example but instead of using a QStandardItem as the internal rootItem I created a private Root class which inherits from QStandardItem:

Code:

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class Root : public QStandardItem
    {
    public:
        QList<QStandardItem*> child;
 
    };

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I do this because I add the top nodes of the sub-models using model1->item(0) and NOT model1->takeItem(0). I want the original models to keep ownership. I will paste some of the methods I implemented in order to do this below. Unfortunately my code doesn't seem to work when plugging it into a "QTreeView-setModel(combined)". The first node expands just fine (it goes from child0->child1->child2->child3) but the other 2 top-nodes throw an ASSERT when i try to expand child2:

Quote:

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File: global\qglobal.cpp
Line: 2090

ASSERT: "i > -1" in file itemviews\qtreeview.cpp, line 3038

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The ASSERT appears to occur when the method "parent(...)" exits.

Does anybody know what I might be doing wrong or if I'm doing something that isn't possible at all.

Code:

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int CombinedTreeModel::rowCount(const QModelIndex &parent) const
{
    QStandardItem *item = getItem(parent);
    if (item == rootItem) {
        return rootItem->child.size();
    }    
    return item->rowCount();
}
 
int CombinedTreeModel::columnCount(const QModelIndex &parent) const
{
    return 1;
}
 
bool CombinedTreeModel::rootContains(QStandardItem *child) const
{
    for (int i = 0; i < rootItem->child.size(); i++) {
        if (child == rootItem->child.at(i)) {
            return true;
        }
    }
    return false;
}
 
QVariant CombinedTreeModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid())
        return QVariant();
 
    if (role != Qt::DisplayRole && role != Qt::EditRole)
        return QVariant();
 
    QStandardItem *item = getItem(index);
 
    return item->data(index.column());
}
 
Qt::ItemFlags CombinedTreeModel::flags(const QModelIndex &index) const
{       
    return getItem(index)->flags();
}
 
QModelIndex CombinedTreeModel::parent ( const QModelIndex & index ) const
{
    if (!index.isValid())
        return QModelIndex();
 
    QStandardItem *childItem = getItem(index);
    QStandardItem *parentItem = childItem->parent();    
 
    // parentItem == rootItem
    if (rootContains(childItem)) {    
        return QModelIndex();        
    }
 
    return createIndex(parentItem->row(), 0, parentItem); 
}
 
QModelIndex CombinedTreeModel::index( int row, int column, const QModelIndex & parent ) const
{
    if (parent.column() > 0)
        return QModelIndex();
 
    QStandardItem* parentItem = getItem(parent);
    QStandardItem* childItem ;
 
    if (parentItem == rootItem) {       
       childItem = rootItem->child.at(row);
    } else {
       childItem = parentItem->child(row);
    }
 
    if (childItem)
        return createIndex(row, column, childItem);
    else
        return QModelIndex();
}
 
QStandardItem *CombinedTreeModel::getItem(const QModelIndex &index) const
{
    if (index.isValid()) {
        QStandardItem *item = static_cast<QStandardItem*>(index.internalPointer());
        if (item) return item;
    }
    return rootItem;
}

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