[Qt-interest] EditableTreeMode example crashing with modeltest

[Daniel Price]

Ok that makes sense.

I've added a check for that in rowCount(), which now returns 0 if the parent column is > 0 which now passes the first test! That's what the example Qt code was doing for index() but their rowCount() code is still wrong.

I think I've also found the problem with my inserts. The insertion code is column-sensitive. If you select the first column, and insert a row, all is fine. But if select the second, the code attempts to add the child to the second column (which as a result of the above change, cannot have children). This was masked by the face that my view was set to select rows, not items so it wasn't obvious that I was selecting the second column everytime.

You need to ensure that:
a) Regardless of the column selected, only the first column can have child nodes inserted.
b) QAbstractItemModel::insertRow(s) must return abort if the parent index column is anything other than zero!

This strangeness is the result of the treemodel being shoe-horned into a table-based framework, I think. It doesn't make sense for a tree to have 'columns' or for any column other than the first to have children (the modeltest checks this).

Thanks for your help!

-----Original Message-----
From: qt-interest-bounces at trolltech.com [mailto:qt-interest-bounces at trolltech.com] On Behalf Of Jan
Sent: 24 November 2009 11:45
To: qt-interest
Subject: Re: [Qt-interest] EditableTreeMode example crashing with modeltest



Daniel Price schrieb:
>> I suppose because if the column is > 0 it usually should not have a
>> parent (and therefore has no valid index) - only a sibling in column 0.

sorry, "should not have a *child*":
I suppose because if the column is > 0 it usually should not have a
*child* (and therefore has no valid index) - only a sibling in column 0.

If you have not changed the example except the part where you populate 
the model I suppose there is something wrong with parenting the children 
(just guessing though).

Jan

> 
> My understanding is that each column is represented by a separate QModelIndex, accessible through the sibling() member function. But each column index must have the same parent otherwise how would QAbstractItemModel::index(row, column, parent) et al work?
> 
>> Maybe make sure you provide as much item data as you have columns
>> (headers) in the root item
> 
>>   QVector<QVariant> rootData;
>>      foreach (QString header, headers)
>>          rootData << header;
> 
> Yes I have done this. If I don't have data, I just get empty columns which I can edit.
> 
> The assert is being triggered because the unit test is asking for the non-zero column-index of a valid row.
> 
> I'm not sure if this is the cause of my original issue (inconsistency between the view and the model) but there is something very wrong here!
> 
> Here is my adaptor in it's entirety (TreeNode is very similar to Qt's TreeItem):
> 
> TreeModelAdaptor::TreeModelAdaptor(const QStringList &headers, QObject *parent)
>         :
>         QAbstractItemModel(parent),
>         m_rootNode(NULL)
> {
>         QVector<QVariant> rootData;
>         foreach (QString header, headers)
>                 rootData << header;
> 
>         m_rootNode = new TreeNode(rootData);
> }
> 
> TreeModelAdaptor::~TreeModelAdaptor()
> {
>         delete m_rootNode;
> }
> 
> QModelIndex TreeModelAdaptor::index(int row, int column, const QModelIndex &parent) const
> {
>         if (parent.isValid() && parent.column() != 0)
>                 return QModelIndex();
> 
>         if (row < 0 || column < 0)
>                 return QModelIndex();
> 
>         TreeNode *parentNode = nodeFromIndex(parent);
> 
>         TreeNode *childNode = parentNode->child(row);
>         if (childNode)
>                 return createIndex(row, column, childNode);
>         else
>                 return QModelIndex();
> }
> 
> QModelIndex TreeModelAdaptor::parent(const QModelIndex &index) const
> {
>         if (!index.isValid())
>                 return QModelIndex();
> 
>         TreeNode *childNode = nodeFromIndex(index);
>         TreeNode *parentNode = childNode->parent();
> 
>         if (parentNode == m_rootNode)
>                 return QModelIndex();
> 
>         return createIndex(parentNode->childNumber(), 0, parentNode);
> }
> 
> int TreeModelAdaptor::rowCount(const QModelIndex &parent) const
> {
>         TreeNode *parentNode = nodeFromIndex(parent);
> 
>         return parentNode->childCount();
> }
> 
> int TreeModelAdaptor::columnCount(const QModelIndex &parent) const
> {
>         return m_rootNode->columnCount();
> }
> 
> QVariant TreeModelAdaptor::headerData(int section, Qt::Orientation orientation, int role) const
> {
>         if (orientation == Qt::Horizontal && role == Qt::DisplayRole)
>                 return m_rootNode->data(section);
> 
>         return QVariant();
> }
> 
> Qt::ItemFlags TreeModelAdaptor::flags(const QModelIndex &index) const
> {
>         if (!index.isValid())
>                 return 0;
> 
>         return Qt::ItemIsEditable | Qt::ItemIsEnabled | Qt::ItemIsSelectable;
> }
> 
> QVariant TreeModelAdaptor::data(const QModelIndex &index, int role) const
> {
>         if (!index.isValid())
>                 return QVariant();
> 
>         if (role != Qt::DisplayRole && role != Qt::EditRole)
>                 return QVariant();
> 
>         TreeNode *node = nodeFromIndex(index);
> 
>         return node->data(index.column());
> }
> 
> bool TreeModelAdaptor::setData(const QModelIndex &index, const QVariant &value, int role)
> {
>         if (role != Qt::EditRole)
>                 return false;
> 
>         TreeNode *node = nodeFromIndex(index);
>         bool result = node->setData(index.column(), value);
> 
>         if (result)
>                 emit dataChanged(index, index);
> 
>         return result;
> }
> 
> bool TreeModelAdaptor::insertColumns(int position, int columns, const QModelIndex &parent)
> {
>         beginInsertColumns(parent, position, position + columns - 1);
>                 bool success = m_rootNode->insertColumns(position, columns);
>         endInsertColumns();
> 
>         return success;
> }
> 
> bool TreeModelAdaptor::removeColumns(int position, int columns, const QModelIndex &parent)
> {
>         beginRemoveColumns(parent, position, position + columns - 1);
>                 bool success = m_rootNode->removeColumns(position, columns);
>         endRemoveColumns();
> 
>         if (m_rootNode->columnCount() == 0)
>                 removeRows(0, rowCount());
> 
>         return success;
> }
> 
> bool TreeModelAdaptor::insertRows(int position, int rows, const QModelIndex &parent)
> {
>         TreeNode *parentNode = nodeFromIndex(parent);
> 
>         beginInsertRows(parent, position, position + rows - 1);
>                 bool success = parentNode->insertChildren(position, rows, m_rootNode->columnCount());
>         endInsertRows();
> 
>         return success;
> }
> 
> bool TreeModelAdaptor::removeRows(int position, int rows, const QModelIndex &parent)
> {
>         TreeNode *parentNode = nodeFromIndex(parent);
> 
>         beginRemoveRows(parent, position, position + rows - 1);
>                 bool success = parentNode->removeChildren(position, rows);
>         endRemoveRows();
> 
>         return success;
> }
> 
> TreeNode* TreeModelAdaptor::nodeFromIndex(const QModelIndex &index) const
> {
>         if (index.isValid())
>         {
>                 TreeNode *item = static_cast<TreeNode*>(index.internalPointer());
>                 if (item)
>                         return item;
>         }
>         return m_rootNode;
> }
> 
> 
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