beginInsertRows doesn't appear to be working?

[steg90]

Hi,

I had this working yesterday, my table was being updated / refreshed by doing the following :

QModelIndex index;
 
	beginInsertRows(index, 1, nAmount);
 
	if( pData )
	{
		for( int i = 0; i < nAmount; i++ )
		{
			m_Data.append(pData[i].strId);
			m_Data.append(pData[i].strTime);
			m_Data.append(pData[i].strData);
			QString strCount;
			strCount.sprintf( "%i", nCount );	
			m_Data.append(strCount);
			nCount++;
		}
	}
	endInsertRows();

QModelIndex index;

	beginInsertRows(index, 1, nAmount);

	if( pData )
	{
		for( int i = 0; i < nAmount; i++ )
		{
			m_Data.append(pData[i].strId);
			m_Data.append(pData[i].strTime);
			m_Data.append(pData[i].strData);
			QString strCount;
			strCount.sprintf( "%i", nCount );	
			m_Data.append(strCount);
			nCount++;
		}
	}
	endInsertRows();

To copy to clipboard, switch view to plain text mode 

Now, the table is only refreshed when it scrolls or I click on it?

Don't know what is wrong?!

Any help is appreciated.
Steve

[jpn]

void QAbstractItemModel::beginInsertRows(const QModelIndex& parent, int first, int last)

Have you noticed that parameters first and last are both indexes (starting from 0)? The last parameter is not the count of inserted items but the index of the last inserted item. I don't know your case, but a range of "from 1 to nAmount" sounds incorrect to me.

[steg90]

Ok thanks,

I now tried setting first and last to one, but still, doesn't refresh?!

Regards,
Steve

[wysota]

I suggest emitting rowsInserted().

[steg90]

This not a private member?

[jpn]

I suggest emitting rowsInserted().

Actually one should not do that because QAbstractItemModel might get "out of sync". Methods beginInsertRows() and endInsertRows() emit corresponding rowsAboutToBeInserted() and rowsInserted() for you.

[steg90]

Thanks jpn,

I think maybe this has something to do with the fact that I cannot dynamically change the amount of rows in my model, for some reason the amount of rows doesn't get changed visually and I'm confused as to why?

Kind regards,
Steve

[wysota]

I think we'd have to see more code to understand what is going on.

How is this thread related to this one?

[steg90]

Ok, here is most of the code :

int DATreeModel::rowCount( const QModelIndex& parent ) const
{
	int nCount = m_Data.count() / 4;
	return nCount;
}
 
int DATreeModel::columnCount(const QModelIndex &) const
{
	return 4;
}
 
QVariant DATreeModel::data( const QModelIndex& index, int role) const
{
	QVariant data;
 
	if (!index.isValid())
		return QVariant();
 
	if (index.row() > (m_Data.size() / 4) ) {
		return QVariant();
	}
 
	if(index.column() > 3 ) {
		return QVariant();
	}
 
	if( role == Qt::DisplayRole )
	{
		int nPos = index.column() + ( 4 * index.row() );
		if( nPos < m_Data.size() )
			data = m_Data.at( nPos );
	}
	return data;
}
 
void DATreeModel::setCanData( CANDATA *pData, int nAmount, int nCount )
{
	beginInsertRows(QModelIndex(), 1, 1);//nAmount );
 
	if( pData )
	{
		for( int i = 0; i < nAmount; i++ )
		{
			m_Data.append(pData[i].strId);
			m_Data.append(pData[i].strTime);
			m_Data.append(pData[i].strData);
			QString strCount;
			strCount.sprintf( "%i", nCount );	
			m_Data.append(strCount);
			nCount++;
 
		}
	}
	endInsertRows();
 
}

int DATreeModel::rowCount( const QModelIndex& parent ) const
{
	int nCount = m_Data.count() / 4;
	return nCount;
}

int DATreeModel::columnCount(const QModelIndex &) const
{
	return 4;
}

QVariant DATreeModel::data( const QModelIndex& index, int role) const
{
	QVariant data;
	
	if (!index.isValid())
		return QVariant();

	if (index.row() > (m_Data.size() / 4) ) {
		return QVariant();
	}

	if(index.column() > 3 ) {
		return QVariant();
	}

	if( role == Qt::DisplayRole )
	{
		int nPos = index.column() + ( 4 * index.row() );
		if( nPos < m_Data.size() )
			data = m_Data.at( nPos );
	}
	return data;
}

void DATreeModel::setCanData( CANDATA *pData, int nAmount, int nCount )
{
	beginInsertRows(QModelIndex(), 1, 1);//nAmount );

	if( pData )
	{
		for( int i = 0; i < nAmount; i++ )
		{
			m_Data.append(pData[i].strId);
			m_Data.append(pData[i].strTime);
			m_Data.append(pData[i].strData);
			QString strCount;
			strCount.sprintf( "%i", nCount );	
			m_Data.append(strCount);
			nCount++;
			
		}
	}
	endInsertRows();

}

To copy to clipboard, switch view to plain text mode 

I'm so confused?

Kind regards,
Steve

[wysota]

You didn't answer my question

[steg90]

Sorry, yes, it is related. I have an emit function when data is read which goes back to the view which just then scrolls the table view.

[jpn]

Does DATreeModel::setCanData() get called only once or many times? I think you might be looking for something like this:

void DATreeModel::setCanData( CANDATA *pData, int nAmount, int nCount )
{
    if( pData )
    {
        int row = rowCount();
        beginInsertRows(QModelIndex(), row, row + nAmount - 1);
        ...
        endInsertRows();
    }
}

void DATreeModel::setCanData( CANDATA *pData, int nAmount, int nCount )
{
    if( pData )
    {
        int row = rowCount();
        beginInsertRows(QModelIndex(), row, row + nAmount - 1);
        ...
        endInsertRows();
    }
}

To copy to clipboard, switch view to plain text mode 

[steg90]

Hi,

setCanData() gets called over and over again from another thread. I tried what you suggested and still the data is not displayed until I click on the table view, also, the rowCount() function still not updating the tableview row amount?

Unless I do something like return 10000 or whatever from the rowCount function, no rows are inserted, I thought rowCount() would do this for you?

Kind regards,
Steve

[steg90]

I'm still struggling with this, the rowCount returns the amount of rows, but the view doesn't reflect this?

Also, QModelIndex() seems to have invalid row and column values in my beginInsertRows...

Can't believe how difficult this is proving for something so trivial!

Regards,
Steve

[wysota]

You can't do it from another thread. Containers are not thread safe. You can only emit a signal from the other thread and catch it in the model and update the model from within the main thread.

[steg90]

Sorry, the worker thread just reads data and emits a signal to main gui thread which then informs the model to update its data. The code below shows the code within the main gui which informs the model of the change with the setCanData function:

if( m_pCanReadThread->isRunning() )  // user may have stopped thread
	{
		if( nCount < 8000 )
		{
			m_ptreeModel->setCanData( pData, nAmount, nCount  );
			QModelIndex index = m_ptreeModel->index( nCount, 0 );
			ui.tableView->scrollTo( index );
		}
		else
		{
			m_pCanReadThread->cancelThread();
		}
	}

if( m_pCanReadThread->isRunning() )  // user may have stopped thread
	{
		if( nCount < 8000 )
		{
			m_ptreeModel->setCanData( pData, nAmount, nCount  );
			QModelIndex index = m_ptreeModel->index( nCount, 0 );
			ui.tableView->scrollTo( index );
		}
		else
		{
			m_pCanReadThread->cancelThread();
		}
	}

To copy to clipboard, switch view to plain text mode 

Regards,
Steve

[wysota]

As a little check emit layoutChanged() at the end of setCanData(). If it makes it work, it means that you have something wrong in your model and using the Modeltest might be a good idea.

[steg90]

Hi,

emit layoutChanged() doesn't have any effect. Still not refreshing the view nor are the rows being inserted.

The only way I can get this to work is to set the row count to a big size right at the begining and click on the table view to get the items to appear, very, very strange and totally not acceptable. Obviously when the table has to scroll, the items appear. One thing I have noticed is that the items in the first column of the table always appear?

Regards,
Steve

[steg90]

Hi,

The problem is that I turn off the signals from the model and don't turn them back on, I do this for speed, having the signals on reduces the speed I can insert data.

Regards,
Steve

[wysota]

You don't have to block signals in this situation as you don't insert one row at a time.