QSqlQuery::isValid returns false

[wysota]

Maybe it emulates last() using next(). It doesn't say anything about either the database or the ODBC driver that handles it.

[haldrik]

Hello, I have a similar problem with an sqlite3 database.

Queries work fine interactively, even queries work fine on the constructor, but on a slot give me this messages on console output:

QSqlQuery::value: not positioned on a valid record
QSqlQuery::value: not positioned on a valid record
QSqlQuery::value: not positioned on a valid record
QSqlQuery::value: not positioned on a valid record
QSqlQuery::value: not positioned on a valid record

I think each message is one for each field in the query string.

The query is executed and the values are retrived, I can use this values without problems, but this messages bothers me, and dirty my console output.

here the implementation of the slot:

void ThirdParties::setLoans(QString id)
{
	qDebug() << id;	
	QSqlQuery queryLoans;
	queryLoans.prepare("SELECT loan_id, date, value, quotas, cancel_quotas, loan_type FROM tblLOANS WHERE thirdparty_id=:id");
	queryLoans.bindValue(":id", id);
	if (!queryLoans.exec())
		QMessageBox::warning(this, tr("Error en la consulta"), queryLoans.lastError().text());
	loanIdComboBox->clear();
	dateEdit->clear();
	valueLineEdit->clear();
	quotasLineEdit->clear();
	cancelQuotasSpinBox->clear();
 
	while (queryLoans.next())
	{
		qDebug() << queryLoans.value(0).toString();
		loanIdComboBox->addItem(queryLoans.value(0).toString());
	}
	queryLoans.first();	
	dateEdit->setDate(queryLoans.value(1).toDate());
	valueLineEdit->setText(queryLoans.value(2).toString());	
	quotasLineEdit->setText(queryLoans.value(3).toString());
     loanTypeComboBox->setCurrentIndex(loanTypeComboBox->findText(queryLoans.value(5).toString()));
	cancelQuotasSpinBox->setValue(queryLoans.value(4).toInt());
}

void ThirdParties::setLoans(QString id)
{
	qDebug() << id;	
	QSqlQuery queryLoans;
	queryLoans.prepare("SELECT loan_id, date, value, quotas, cancel_quotas, loan_type FROM tblLOANS WHERE thirdparty_id=:id");
	queryLoans.bindValue(":id", id);
	if (!queryLoans.exec())
		QMessageBox::warning(this, tr("Error en la consulta"), queryLoans.lastError().text());
	loanIdComboBox->clear();
	dateEdit->clear();
	valueLineEdit->clear();
	quotasLineEdit->clear();
	cancelQuotasSpinBox->clear();

	while (queryLoans.next())
	{
		qDebug() << queryLoans.value(0).toString();
		loanIdComboBox->addItem(queryLoans.value(0).toString());
	}
	queryLoans.first();	
	dateEdit->setDate(queryLoans.value(1).toDate());
	valueLineEdit->setText(queryLoans.value(2).toString());	
	quotasLineEdit->setText(queryLoans.value(3).toString());
     loanTypeComboBox->setCurrentIndex(loanTypeComboBox->findText(queryLoans.value(5).toString()));
	cancelQuotasSpinBox->setValue(queryLoans.value(4).toInt());
}

To copy to clipboard, switch view to plain text mode 

[jacek]

Do the errors disappear when you comment out lines #20--#25?

[haldrik]

Don't dessapear. Even I commented all lines exept the declaration, prepare-bindValue and executed lines of the query, the message still appear.

I repeat, this message appear only in this slot, on the constructor don't appear.

[haldrik]

Hello. Now I solved my problem.

The problem is using multiple connections (QObject::connect), the slot avobe call other signal i.e:

connect(idComboBox, SIGNAL(currentIndexChanged(QString)),
			this, SLOT(setLoans(QString)));	
 
	connect(loanIdComboBox, SIGNAL(currentIndexChanged(int)),
			this, SLOT(setLoanValues(int)));

connect(idComboBox, SIGNAL(currentIndexChanged(QString)),
			this, SLOT(setLoans(QString)));	

	connect(loanIdComboBox, SIGNAL(currentIndexChanged(int)),
			this, SLOT(setLoanValues(int)));

To copy to clipboard, switch view to plain text mode 

loanIdComboBox->clear(); call currentIndexChanged, on that connection I have the same query and for this behavior was the error.

I correct this behavior using at begin of slot loanIdComboBox->blockSignals(true) and then on final of slot loanIdComboBox->blockSignals(false).

DBG is a great help.