[Qt-interest] How to remove items from QSqlTableModelvia QTableView

[Sven Grunewaldt]

Hi Alex,

because of this I created QPersistentModelIndexes, as they should be 
updated by the model when the rows are changed. Sadly, they seem to get 
invalid after the first one is removed, which I don't understand...at all...

Regards,
Sven Grunewaldt

Am 27.04.2009 21:29, schrieb Malyushytsky, Alex:
> According to my understanding it does not work, because the way you remove rows changes indexing.
> For example if u need to remove rows 3,4,7, and are trying to remove 3 first,  row 4 becomes 3, 7 becomes 6.
>
> To fix  problem try to remove the rows  in decrementing order, something like
> for ( int row = tmp.size()-1; row>-1; row--)
> { ..........
> }
>
> Also, according to the documentation selectedIndexes() do not contain duplicates, but is not sorted.
> So you would need to pre-sort it.
>
> I would say that even you can make this approach work, it is not at efficient.
> What I would do, instead of using selectedIndexes() I would iterate (in reverse direction) through the each index,
> check if it is selected, remove it.
>
> Hope this helps,
>       Alex
>
>
>
> From: qt-interest-bounces at trolltech.com [mailto:qt-interest-bounces at trolltech.com] On Behalf Of Sven Grunewaldt
> Sent: Monday, April 27, 2009 12:06 PM
> To: qt-interest at trolltech.com
> Subject: Re: [Qt-interest] How to remove items from QSqlTableModelvia QTableView
>
> Hi,
>
> actually this doesn't seem to work and I again don't understand why ;)
>
> My function:
> ---
> void BerichteOrk::removeSelectedFromTableView(QTableView* view)
> {
>      QAbstractItemModel* model = view->model();
>
>      const QModelIndexList tmp = view->selectionModel()->selectedIndexes();
>      QList<QPersistentModelIndex>  indexes;
>
>      for (int i = 0; i<  tmp.size(); i++)
>      {
>          qDebug()<<  tmp.at(i).internalId()<<  tmp.at(i).isValid()<<  tmp.at(i).row();
>          indexes.append(QPersistentModelIndex(tmp.at(i)));
>          qDebug()<<  tmp.at(i).internalId()<<  tmp.at(i).isValid();
>      }
>      qDebug()<<  "";
>      for (int i = 0; i<  indexes.size(); i++)
>      {
>          qDebug()<<  indexes.at(i).internalId()<<  indexes.at(i).isValid()<<  indexes.at(i).row();
>          model->removeRow(indexes.at(i).row());
>          qDebug()<<  indexes.at(i).internalId()<<  indexes.at(i).isValid();
>      }
>
>      view->resizeColumnsToContents();
>      view->resizeRowsToContents();
>      view->horizontalHeader()->setStretchLastSection(true);
> }
> ---
>
> qDebug() output:
> ---
> 0 true 1
> 0 true
> 0 true 2
> 0 true
> 0 true 3
> 0 true
> 0 true 4
> 0 true
>
> 0 true 1
> 0 false
> 0 false -1
> 0 false
> 0 false -1
> 0 false
> 0 false -1
> 0 false
> ---
>
> As I understand the documentation this _should_ work...
>
> Regards,
> Sven Grunewaldt
>
> Am 27.04.2009 01:15, schrieb Tony Rietwyk:
> Hi Sven,
>
> Correct me if I'm wrong, but I don't think you should make any assumptions about the order of the indexes returned from selectedIndexes.
>
> I suggest converting them to persistent indexes first, that way subsequent indexes will get updated by the view as you delete them.
>
> Hope that helps,
>
> Tony.
>
> -----Original Message-----
> From: qt-interest-bounces at trolltech.com [mailto:qt-interest-bounces at trolltech.com] On Behalf Of Sven Grunewaldt
> Sent: Sunday, 26 April 2009 01:58
> To: qt-interest at trolltech.com
> Subject: Re: [Qt-interest] How to remove items from QSqlTableModelvia QTableView
> Haha, oh god. I can't believe I didn't notice this... Thanks! :)
> Sometimes you need another pair of eyes to see the obvious.
>
> Regards,
> Sven Grunewaldt
>
> Am 25.04.2009 17:50, schrieb Scott Aron Bloom:
> Your algorithm fails for the same reason this algorithm fails:
>
> QList<  int>  values;
> //make a list where value[ ii ] == ii
> for( int ii = 0; ii<  10; ++ii )
>     values<<  ii;
>
>
> // remove value 3, 4, 5
> values.removeAt( 3 );
> values.removeAt( 4 );
> values.removeAt( 5 );
>
> // which actually removes 3,5 and 7 (I think... :) )
> The problem is, since you are removing index.row() 1 at a time, your row
> value will most likely NOT be valid after the remove.
>
>
> Scott
>
>
>
> -----Original Message-----
> From: qt-interest-bounces at trolltech.com [mailto:qt-interest-
> bounces at trolltech.com] On Behalf Of Sven Grunewaldt
> Sent: Saturday, April 25, 2009 8:31 AM
> To: qt-interest at trolltech.com
> Subject: [Qt-interest] How to remove items from QSqlTableModel via
>
> QTableView
>
> Hi,
>
> I have a QTableView which lies on top of a QSqlTableModel and a Button
> to remove the currently selected rows. It seems that my implementation
> of the buttons function does something wrong.
> Sometimes not all selected items are removed and I just can't see why,
> maybe someone finds my mistake:
>
> void BerichteOrk::on_removeSchuleButton_clicked()
> {
>       const QModelIndexList tmp =
> schuleView->selectionModel()->selectedIndexes();
>
>       foreach (QModelIndex index, tmp)
>       {
>           schuleModel->removeRow(index.row());
>       }
> }
>
> Regards,
> Sven Grunewaldt
>
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