Validation of correct database connection

[cecchinoSMI]

I'm trying to connect with a database created with Microsoft Sql Express 2012. I'm using qt 5.2.1, and at the end of the connection implementetion I write some code to have a validation. But an error accure, and I don't know why. The program is structured in this way:

-in the MainWindow of qt GUI application there is a Button, if you click on this Button you open a Dialog Application. -in the Dialog Application is devolped the connection.

here the .h code of the Dialog Application:

#ifndef DATABASE_H
#define DATABASE_H
 
#include <QDialog>
 
namespace Ui {
class DataBase;
}
 
class DataBase : public QDialog
{
    Q_OBJECT
 
 
 
public:
    explicit DataBase(QWidget *parent = 0);
    ~DataBase();
 
private:
    Ui::DataBase *ui;
};
 
#endif // DATABASE_H

#ifndef DATABASE_H
#define DATABASE_H

#include <QDialog>

namespace Ui {
class DataBase;
}

class DataBase : public QDialog
{
    Q_OBJECT



public:
    explicit DataBase(QWidget *parent = 0);
    ~DataBase();

private:
    Ui::DataBase *ui;
};

#endif // DATABASE_H

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here the relative .cpp code of Dialog Application:

#include <database.h>
#include <ui_database.h>
#include <QtSql>
#include <QtDebug>
#include <iostream>
DataBase::DataBase(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::DataBase)
{
 
    QString servername="MARCO-VAIO";
    QString dbname="IfaCOM";
    QSqlDatabase db = QSqlDatabase::addDatabase("QODBC");
    db.setConnectOptions();
    QString dsn = QString("DRIVER={SQL Native Client}; SERVER=%1; DATABASE=%2;TRUSTED_CONNECTION=Yes;").arg(servername).arg(dbname);
    db.setDatabaseName(dsn);
    if(db.open()){
        ui->label->setText("Connected....");
    }
 
 
}
 
DataBase::~DataBase()
{
    delete ui;
}

#include <database.h>
#include <ui_database.h>
#include <QtSql>
#include <QtDebug>
#include <iostream>
DataBase::DataBase(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::DataBase)
{

    QString servername="MARCO-VAIO";
    QString dbname="IfaCOM";
    QSqlDatabase db = QSqlDatabase::addDatabase("QODBC");
    db.setConnectOptions();
    QString dsn = QString("DRIVER={SQL Native Client}; SERVER=%1; DATABASE=%2;TRUSTED_CONNECTION=Yes;").arg(servername).arg(dbname);
    db.setDatabaseName(dsn);
    if(db.open()){
        ui->label->setText("Connected....");
    }


}

DataBase::~DataBase()
{
    delete ui;
}

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and here the error that accured:
Cattura.JPG

Please check this issue...thanks in advance.

[anda_skoa]

You are missing the ui->setupUi(this) call, so your call to ui->label accesses an invalid pointer.

Cheers,
_

[cecchinoSMI]

thank you very much...