How would I open a new window from a button in the dialog using Qt Creator?

[atoivan]

I'm new to qt programming.so please go easy on me. I have one dialog designed in Qt5.4, A modal main Window or a dialog is to be opened when a button is pressed.but i can not find the setModal object to set the Qwindow and when i press the button the dialog dose not hid and neither the Qwindow or dialog will open. here are my codes

Login.h

#ifndef LOGIN_H
#define LOGIN_H
 
#include <QDialog>
#include <QCoreApplication>
#include <QApplication>
#include <QtSql/QSql>
#include <QtSql/QSqlDatabase>
#include <QtSql/QSqlDriver>
#include <QtSql/QSqlQuery>
#include <QDebug>
#include "next_page.h"
#include "main_page.h"
 
namespace Ui {
class Login;
}
 
class Login : public QDialog
{
    Q_OBJECT
 
public:
    // function for database connetion
    QSqlDatabase MyDB;    //object for connection
/*
    void  CloseConncetion()
    {
        MyDB.close();
        MyDB.removeDatabase(QSqlDatabase::defaultConnection);
    }
*/
    void CloseConncetion()
    {
        QString connection;
        connection = MyDB.connectionName();
        MyDB=QSqlDatabase();
        MyDB.removeDatabase(connection);
    }
 
 
    bool OpenConncetion(){
        QSqlDatabase MyDB = QSqlDatabase::addDatabase("QMYSQL");
        MyDB .setHostName("localhost");
       MyDB.setDatabaseName("project");
      MyDB.setUserName("lord-ivan");
     MyDB.setPassword("Ir0ngo@t");
 
        if (!MyDB.open())
        {
                qDebug()<<("Datebase not Connected");
 
        return false;
 
        }
            else
        {
                qDebug()<<("Datebase Connected");
 
                return true;
        }
 
    }
public:
    explicit Login(QWidget *parent = 0);
    ~Login();
 
private slots:
    void on_pushButton_Login_clicked();
 
    void on_pushButton_clicked();
 
private:
    Ui::Login *ui;
};
 
#endif // LOGIN_H

#ifndef LOGIN_H
#define LOGIN_H

#include <QDialog>
#include <QCoreApplication>
#include <QApplication>
#include <QtSql/QSql>
#include <QtSql/QSqlDatabase>
#include <QtSql/QSqlDriver>
#include <QtSql/QSqlQuery>
#include <QDebug>
#include "next_page.h"
#include "main_page.h"

namespace Ui {
class Login;
}

class Login : public QDialog
{
    Q_OBJECT

public:
    // function for database connetion
    QSqlDatabase MyDB;    //object for connection
/*
    void  CloseConncetion()
    {
        MyDB.close();
        MyDB.removeDatabase(QSqlDatabase::defaultConnection);
    }
*/
    void CloseConncetion()
    {
        QString connection;
        connection = MyDB.connectionName();
        MyDB=QSqlDatabase();
        MyDB.removeDatabase(connection);
    }


    bool OpenConncetion(){
        QSqlDatabase MyDB = QSqlDatabase::addDatabase("QMYSQL");
        MyDB .setHostName("localhost");
       MyDB.setDatabaseName("project");
      MyDB.setUserName("lord-ivan");
     MyDB.setPassword("Ir0ngo@t");

        if (!MyDB.open())
        {
                qDebug()<<("Datebase not Connected");

        return false;

        }
            else
        {
                qDebug()<<("Datebase Connected");

                return true;
        }

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

private slots:
    void on_pushButton_Login_clicked();

    void on_pushButton_clicked();

private:
    Ui::Login *ui;
};

#endif // LOGIN_H

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Login.cpp

#include "login.h"
#include "ui_login.h"
 
Login::Login(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Login)
{
    ui->setupUi(this);
 
 
    if (!OpenConncetion())
        ui->label_Status->setText("Datebase not Connected");
    else
       ui->label_Status->setText("Datebase Connected");
 
}
 
Login::~Login()
{
    delete ui;
}
 
void Login::on_pushButton_Login_clicked()
{
 
 
    QString username,password;
 
    username=ui->lineEdit_UserName->text();
    password=ui->lineEdit_PassWord->text();
 
    if(!OpenConncetion())
    {
        qDebug()<<"Datebase not Connected";
        return;
    }
 
QSqlQuery query;
 
if(query.exec("SELECT * FROM Users where UserName ='"+username+"' and Password ='"+password+"'")) // query for input
{
    int count=0;
    while(query.next())
  {
 
        count++;
    }
if (count==1)
{
     ui->label_Status->setText("Username and password is correct");
 
CloseConncetion();  // it is important to call this funcion to open the connection.
 
this->hide();
Next_Page page;
page.setModal(true);
page.exec();
 
}
if (count>1)
        ui->label_Status->setText("Duplicate Username and password is correct");
if (count<1)
    ui->label_Status->setText("Username and password is not correct");
 
 
}
 
 
 
}
 
void Login::on_pushButton_clicked()
{
 
 
 
    QString username,password;
 
    username=ui->lineEdit_UserName->text();
    password=ui->lineEdit_PassWord->text();
 
    if(!OpenConncetion())
    {
        qDebug()<<"Datebase not Connected";
        return;
    }
 
QSqlQuery query;
 
if(query.exec("SELECT * FROM Users where UserName ='"+username+"' and Password ='"+password+"'")) // query for input
{
    int count=0;
    while(query.next())
  {
 
        count++;
    }
if (count==1)
{
     ui->label_Status->setText("Username and password is correct");
 
CloseConncetion();  // it is important to call this funcion to open the connection.
 
this->hide();
Main_Page Mpage;
Mpage.window();
 
Mpage.show();
 
}
if (count>1)
        ui->label_Status->setText("Duplicate Username and password is correct");
if (count<1)
    ui->label_Status->setText("Username and password is not correct");
 
 
}
}

#include "login.h"
#include "ui_login.h"

Login::Login(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Login)
{
    ui->setupUi(this);


    if (!OpenConncetion())
        ui->label_Status->setText("Datebase not Connected");
    else
       ui->label_Status->setText("Datebase Connected");

}

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

void Login::on_pushButton_Login_clicked()
{


    QString username,password;

    username=ui->lineEdit_UserName->text();
    password=ui->lineEdit_PassWord->text();

    if(!OpenConncetion())
    {
        qDebug()<<"Datebase not Connected";
        return;
    }

QSqlQuery query;

if(query.exec("SELECT * FROM Users where UserName ='"+username+"' and Password ='"+password+"'")) // query for input
{
    int count=0;
    while(query.next())
  {

        count++;
    }
if (count==1)
{
     ui->label_Status->setText("Username and password is correct");

CloseConncetion();  // it is important to call this funcion to open the connection.

this->hide();
Next_Page page;
page.setModal(true);
page.exec();

}
if (count>1)
        ui->label_Status->setText("Duplicate Username and password is correct");
if (count<1)
    ui->label_Status->setText("Username and password is not correct");


}



}

void Login::on_pushButton_clicked()
{



    QString username,password;

    username=ui->lineEdit_UserName->text();
    password=ui->lineEdit_PassWord->text();

    if(!OpenConncetion())
    {
        qDebug()<<"Datebase not Connected";
        return;
    }

QSqlQuery query;

if(query.exec("SELECT * FROM Users where UserName ='"+username+"' and Password ='"+password+"'")) // query for input
{
    int count=0;
    while(query.next())
  {

        count++;
    }
if (count==1)
{
     ui->label_Status->setText("Username and password is correct");

CloseConncetion();  // it is important to call this funcion to open the connection.

this->hide();
Main_Page Mpage;
Mpage.window();

Mpage.show();

}
if (count>1)
        ui->label_Status->setText("Duplicate Username and password is correct");
if (count<1)
    ui->label_Status->setText("Username and password is not correct");


}
}

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[anda_skoa]

You usually don't need to set the modality of a dialog.
show() brings it up as a non-modal dialog and exec() brings it up as modal.

From a quick look your Next_Page window should open, but of course Main_Page will not (Mpage doesn't live long enough).

Cheers,
_