(Another) segmentation fault

[Lebowski]

Following that example I changed

1.
      void GlavnoO :: pushButton3_clicked()
      {
          bool ok = FALSE;
          ok = povezava.baza->isOpen();
      }

1.
      void GlavnoO :: pushButton3_clicked()
      {
          bool ok = FALSE;
          ok = povezava.baza->isOpen();
      }

To copy to clipboard, switch view to plain text mode 

to

void GlavnoO::pushButton3_clicked()
{
    bool ok = FALSE;
    QSqlDatabase *baza = QSqlDatabase::database();
    ok = baza->isOpen();
}

void GlavnoO::pushButton3_clicked()
{
    bool ok = FALSE;
    QSqlDatabase *baza = QSqlDatabase::database();
    ok = baza->isOpen();
}

To copy to clipboard, switch view to plain text mode 

It compiles normally but it crashes with segmentation fault again when I press that button.

And I have to use pointers cause I have this in my Qt Assistant QSqlDatabase Reference:

Static Public Members
QSqlDatabase * addDatabase ( const QString & type, const QString & connectionName = defaultConnection )
QSqlDatabase * addDatabase ( QSqlDriver * driver, const QString & connectionName = defaultConnection )
QSqlDatabase * database ( const QString & connectionName = defaultConnection, bool open = TRUE )
void removeDatabase ( const QString & connectionName )
void removeDatabase ( QSqlDatabase * db )
bool contains ( const QString & connectionName = defaultConnection )
QStringList drivers ()
void registerSqlDriver ( const QString & name, const QSqlDriverCreatorBase * creator )
bool isDriverAvailable ( const QString & name )

[jpn]

Notice also the sentence in docs:

If connectionName does not exist in the list of databases, 0 is returned.

So add a check for null pointer:

void GlavnoO::pushButton3_clicked()
{
	bool ok = FALSE;
	QSqlDatabase *baza = QSqlDatabase::database();
	if (baza)
	{
		ok = baza->isOpen();
	}
}

void GlavnoO::pushButton3_clicked()
{
	bool ok = FALSE;
	QSqlDatabase *baza = QSqlDatabase::database();
	if (baza)
	{
		ok = baza->isOpen();
	}
}

To copy to clipboard, switch view to plain text mode 

[Lebowski]

Yep, that solves the segmentation fault. But I would still like to know how to acces databse connection which I opened in another form.

[wysota]

And I have to use pointers

Sure, you're using Qt3 and I was looking at Qt4 docs.

But I would still like to know how to acces databse connection which I opened in another form.

First check if addDatabase returns a valid database handle.

[Lebowski]

I did check with this code in form povezava (povezava.ui.h):

bool ok = baza->open();
    if (!ok) {QMessageBox::warning (this, "Pozor!!!!!!!!!!!", "not working",1,0,0);}
	else  {
	QMessageBox::information ( this, "Uspeh!!!!!!!!!", "working",1,0,0 );
	close();
    };

bool ok = baza->open();
    if (!ok) {QMessageBox::warning (this, "Pozor!!!!!!!!!!!", "not working",1,0,0);}
	else  {
	QMessageBox::information ( this, "Uspeh!!!!!!!!!", "working",1,0,0 );
	close();
    };

To copy to clipboard, switch view to plain text mode 

And it certainly works.

But now I need to access it from a different form, from file glavnoo.ui.h.

[wysota]

So why don't you use QSqlDatabase::database()?

[Lebowski]

I am using that.

void GlavnoO::test_clicked()
{
    bool ok = FALSE;
    QSqlDatabase *baza = QSqlDatabase::database();
    if (baza) {
	ok = baza->isOpen();
    };

void GlavnoO::test_clicked()
{
    bool ok = FALSE;
    QSqlDatabase *baza = QSqlDatabase::database();
    if (baza) {
	ok = baza->isOpen();
    };

To copy to clipboard, switch view to plain text mode 

Originally it was without 'if (baza) ...' statement.

[wysota]

So what's wrong with that? The form you use it in doesn't matter. You can use QSqlDatabase::database() from anywhere. Just makesure addDatabase() has been invoked earlier.

[Lebowski]

Yep, it does work now!! Thanx all.

Seems I was missing QSqlDatabase::database() statement so my 'baza' pointer had a random value.