sylvainb
25th February 2009, 14:13
I'm using QtSql (sqlite database in memory) and I need to remove the first column from my tables. Unfortunately, when I do this and I attempt to change a value using setData() I get a "QSqlQuery::value: not positioned on a valid record" error yet I'm able to retreive the current valus using a call to data() using the exact same QModelIndex. Has anyobody ever seen this problem or have a work around? Below is an example which show the problem. To remove the first column, you just need to run the compiled binary with at least one argument:
#include <QtGui>
#include <QtSql>
#include <QWidget>
#include <QDebug>
#include <iostream>
int main(int argc, char *args[])
{
QApplication app(argc, args);
// Create an im memory database
QSqlDatabase db = QSqlDatabase::addDatabase( "QSQLITE" );
db.setDatabaseName( ":memory:" );
if ( !db.open() )
{
qCritical( "ERROR in opening the internal database" );
}
// Create a table in the database
QSqlQuery query = db.exec(QString("create table test (id INTEGER PRIMARY KEY AUTOINCREMENT)"));
// Add a column in the table using a query
query.exec("ALTER TABLE test ADD col2 VARCHAR(50);");
query.exec("ALTER TABLE test ADD col3 VARCHAR(50);");
// Add a row to the column
query.exec("INSERT INTO test ('col2','col3') VALUES ('something','last');");
bool removeFirstColumn = argc > 1;
// Create a table model for the table view
QSqlTableModel *model= new QSqlTableModel;
model->setTable("test");
model->setEditStrategy(QSqlTableModel::OnFieldChange);
if (removeFirstColumn) {
model->removeColumns(0,1);
}
model->select();
// Cteate a table view and display it
QTableView table;
table.setModel(model);
table.show();
int row = 0;
int col ;
if (removeFirstColumn) {
col = 1 ;
} else {
col = 2;
}
QModelIndex index = model->index(row, col);
//NOTE: current value should be "last", this works
qDebug() << "value before change at row=" << row << "col=" << col << model->data( index ).toString();
//Attempt to change the value
QVariant newValue = "new value";
model->setData( index, newValue);
qDebug() << "value after change at row=" << row << "col=" << col << model->data( index ).toString();
return app.exec();
}
Below is my output:
C:\Qt\examples\sql>sql remove
value before change at row= 0 col= 1 "last"
QSqlQuery::value: not positioned on a valid record
value after change at row= 0 col= 1 "last"
#include <QtGui>
#include <QtSql>
#include <QWidget>
#include <QDebug>
#include <iostream>
int main(int argc, char *args[])
{
QApplication app(argc, args);
// Create an im memory database
QSqlDatabase db = QSqlDatabase::addDatabase( "QSQLITE" );
db.setDatabaseName( ":memory:" );
if ( !db.open() )
{
qCritical( "ERROR in opening the internal database" );
}
// Create a table in the database
QSqlQuery query = db.exec(QString("create table test (id INTEGER PRIMARY KEY AUTOINCREMENT)"));
// Add a column in the table using a query
query.exec("ALTER TABLE test ADD col2 VARCHAR(50);");
query.exec("ALTER TABLE test ADD col3 VARCHAR(50);");
// Add a row to the column
query.exec("INSERT INTO test ('col2','col3') VALUES ('something','last');");
bool removeFirstColumn = argc > 1;
// Create a table model for the table view
QSqlTableModel *model= new QSqlTableModel;
model->setTable("test");
model->setEditStrategy(QSqlTableModel::OnFieldChange);
if (removeFirstColumn) {
model->removeColumns(0,1);
}
model->select();
// Cteate a table view and display it
QTableView table;
table.setModel(model);
table.show();
int row = 0;
int col ;
if (removeFirstColumn) {
col = 1 ;
} else {
col = 2;
}
QModelIndex index = model->index(row, col);
//NOTE: current value should be "last", this works
qDebug() << "value before change at row=" << row << "col=" << col << model->data( index ).toString();
//Attempt to change the value
QVariant newValue = "new value";
model->setData( index, newValue);
qDebug() << "value after change at row=" << row << "col=" << col << model->data( index ).toString();
return app.exec();
}
Below is my output:
C:\Qt\examples\sql>sql remove
value before change at row= 0 col= 1 "last"
QSqlQuery::value: not positioned on a valid record
value after change at row= 0 col= 1 "last"