rowCount() is calling for all the top level items

[prasad_N]

This example shows that the view does not query the whole model when it initializes:

No, it's a default behaviour of QTreeView since the tree wants to know whether each of the items has child items:

these 2 statements are conflicting right ?

1. In my model rowCount is calling for all the top level items.

my model is :

QModelIndex TreeModel::index( int row, int column, const QModelIndex &parent ) const
{
    if ( ! hasIndex(row, column, parent) )
        return QModelIndex();
 
   TreeItem *parentItem;
 
    if ( ! parent.isValid() )
     parentItem = m_rootItem;
    else
     parentItem = static_cast<TreeItem*>( parent.internalPointer() );
 
    TreeItem *childItem = parentItem->child( row );
    if ( childItem )
     return createIndex( row, column, childItem );
    else
     return QModelIndex();
}
 
QModelIndex TreeModel::parent( const QModelIndex &index ) const
{
    if ( ! index.isValid() )
        return QModelIndex();
 
    TreeItem *childItem  = static_cast<TreeItem*>( index.internalPointer() );
    TreeItem *parentItem = childItem->parent();
 
    if ( (parentItem == m_rootItem)  || (parentItem == NULL))
        return QModelIndex();
 
    return createIndex( parentItem->row(), 0, parentItem );
}
 
int TreeModel::rowCount( const QModelIndex &parent ) const
{
       if ( parent.column() > 0 )
        return 0;
 
    TreeItem *parentItem;
    if ( ! parent.isValid() )
        parentItem = m_rootItem;
    else
        parentItem = static_cast<TreeItem*>( parent.internalPointer() );
 
    return parentItem->childCount();
}

QModelIndex TreeModel::index( int row, int column, const QModelIndex &parent ) const
{
    if ( ! hasIndex(row, column, parent) )
        return QModelIndex();

   TreeItem *parentItem;

    if ( ! parent.isValid() )
     parentItem = m_rootItem;
    else
     parentItem = static_cast<TreeItem*>( parent.internalPointer() );

    TreeItem *childItem = parentItem->child( row );
    if ( childItem )
     return createIndex( row, column, childItem );
    else
     return QModelIndex();
}

QModelIndex TreeModel::parent( const QModelIndex &index ) const
{
    if ( ! index.isValid() )
        return QModelIndex();

    TreeItem *childItem  = static_cast<TreeItem*>( index.internalPointer() );
    TreeItem *parentItem = childItem->parent();

    if ( (parentItem == m_rootItem)  || (parentItem == NULL))
        return QModelIndex();

    return createIndex( parentItem->row(), 0, parentItem );
}

int TreeModel::rowCount( const QModelIndex &parent ) const
{
       if ( parent.column() > 0 )
        return 0;

    TreeItem *parentItem;
    if ( ! parent.isValid() )
        parentItem = m_rootItem;
    else
        parentItem = static_cast<TreeItem*>( parent.internalPointer() );

    return parentItem->childCount();
}

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2. When I change your model little bit on order to check tree function calling. in the index if(parent.isValid()) is not at all executing.

int rowCount(const QModelIndex &parent = QModelIndex()) const {
    qDebug() << Q_FUNC_INFO << parent;
    if(parent.isValid()) return 2;    //each parent with 2 child
    return 10;                            // 10 top most parrents
  }
 
  QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const {
      if(parent.isValid()){        // this condition is not at all executing 
          qDebug() << "Yes isValid = " << parent.child(row, column);
          return createIndex(row, column, (void*)parent.child(row, column).internalPointer());   //create &return child index
      }
 
    return createIndex(row, column, (void*)0);    // return top most elements index's
  }

int rowCount(const QModelIndex &parent = QModelIndex()) const {
    qDebug() << Q_FUNC_INFO << parent;
    if(parent.isValid()) return 2;    //each parent with 2 child
    return 10;                            // 10 top most parrents
  }

  QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const {
      if(parent.isValid()){        // this condition is not at all executing 
          qDebug() << "Yes isValid = " << parent.child(row, column);
          return createIndex(row, column, (void*)parent.child(row, column).internalPointer());   //create &return child index
      }

    return createIndex(row, column, (void*)0);    // return top most elements index's
  }

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What wrong am I doing here ?

I don't want to use treeItems in my model for tree(if possible, I think it is possible with above implementation).