QSqlTableModel inserts empty rows

[Nesbitt]

Hi

I have noticed that QSqlTableModel inserts empty rows after setting setFilter when previous setFilter returned 0 rows. I am using Qt 4.3.4.

Similar problems ware described in:
Bug 170783
Bug 180617
Bug 194644
Bug 203724

I have check the sequence of signals emitted by QSqlTableModel (QAbstractItemModel). My example table (database is SQLite):

QSqlQuery q;
q.exec(QLatin1String("create table t1(id integer primary key, f1 varchar)"));
q.exec(QLatin1String("insert into t1(f1) values('a')"));
q.exec(QLatin1String("insert into t1(f1) values('a')"));
q.exec(QLatin1String("insert into t1(f1) values('a')"));
q.exec(QLatin1String("insert into t1(f1) values('b')"));
q.exec(QLatin1String("insert into t1(f1) values('b')"));

QSqlQuery q;
q.exec(QLatin1String("create table t1(id integer primary key, f1 varchar)"));
q.exec(QLatin1String("insert into t1(f1) values('a')"));
q.exec(QLatin1String("insert into t1(f1) values('a')"));
q.exec(QLatin1String("insert into t1(f1) values('a')"));
q.exec(QLatin1String("insert into t1(f1) values('b')"));
q.exec(QLatin1String("insert into t1(f1) values('b')"));

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Here is the sequence of signals:

1. setfilter("f1 = 'c'") - model sholud return 0 rows
   
   1. rowsAboutToBeRemoved
   2. rowsRemoved
   3. modelAboutToBeReset
   4. modelReset
   
   Now model is empty.
2. setFilter("f1 = 'a'") - model should return 3 rows
   
   1. modelAboutToBeReset (why? model was already reset at the end of previous step)
   2. rowsAboutToBeInserted
   3. rowsInserted (everything is ok, i can see 3 rows)
   4. modelReset (here is the problem)
   
   Now model has 3 empty rows.
3. setFilter("f1 = 'a'") - same as setp 2
   
   1. rowsAboutToBeInserted
   2. rowsInserted
   
   Now model has 6 rows (3 empty and 3 valid).

It looks like resetting model in step 2 is not necessary. Is there any way to get rid of it? Or to fix the order of signals? modelReset sholud be right after modelAboutToBeReset not after rowsInserted.

Unfortunately QAbstractItemModel::reset() is not virtual so I cannot reimplement it.

Thanks.

PS Example program is in the attachment.

[Nesbitt]

Ok. The simplest (and probably most inefficient) solution is:

1. disconnect model from QTableView
2. setup filter twice
3. connect model to QTableView

So updateFilter() in my example now looks like this:

void ModelTest::updateFilter()
{
	bool modelIsEmpty = (model->rowCount() == 0);
 
	if(modelIsEmpty)
		ui.tableView->setModel(0);
 
	model->setFilter(QString("f1 = '%1'").arg(ui.lineEdit->text()));
 
	if(modelIsEmpty){
		model->setFilter(QString("f1 = '%1'").arg(ui.lineEdit->text()));
		ui.tableView->setModel(model);
	}
}

void ModelTest::updateFilter()
{
	bool modelIsEmpty = (model->rowCount() == 0);

	if(modelIsEmpty)
		ui.tableView->setModel(0);
		
	model->setFilter(QString("f1 = '%1'").arg(ui.lineEdit->text()));

	if(modelIsEmpty){
		model->setFilter(QString("f1 = '%1'").arg(ui.lineEdit->text()));
		ui.tableView->setModel(model);
	}
}

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[notalklu]

Maybe this is the only to solve this problem,Thank you