How to Close QApplication from MainWindow

Question

2.00/5 (1 vote)

See more:

I writing a QT gui app. My App has a window with a combo box with the id of records that a user can pick to edit. I have code in the MainWindow class that executes a sql query to populate the combo box. I have code to check for sql errors. After informing the user that there was an error I want to shutdown the whole app. I googled this for hours. I've tried close, QCoreApplication::exit() in the MainWindow class and that doesn't work. Please help.

Posted 4-Dec-15 6:16am

JohnnyG62

Add a Solution

3 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

JohnnyG62 · Answer 1 · 2015-12-07T09:46:00

I found a solution. Any place I get a sql error, I simply close the form not abort the app. Also using this link I found a nice way of showing my login dialog so it doesn't show the MainWindow before a successful login.

http://stackoverflow.com/questions/5527908/qt-how-to-open-qdialog-when-main-application-done-fully-to-load-all-widgets[^]

I made this change to the suggested code. You need to design the login gui dialog yourself.

void MainWindow::showDialog()
{
    this->hide();
    TryAgain=true;
    while (TryAgain==true)
    {
        mLogin =new LoginDialog(this);

        mLogin->exec();

    }

   

    mLogin->close();
    if (Abort==true)
    {
       
        qApp->closeAllWindows();

    }
    else this->show();
}

Here is the code in my login dialog

#include "logindialog.h"
#include "ui_logindialog.h"
#include <mainwindow.h>
#include <menu.h>
#include <QApplication>
#include <QDebug>
#include <QString>
#include <QtSql/QSql>
#include <QtSql/QSqlDatabase>
#include <QtSql/QSqlQuery>
#include <QtSql/QSqlError>
#include <QMessageBox>
#include "Globals.h"




 LoginDialog::LoginDialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::LoginDialog)
{
    ui->setupUi(this);
    ui->txtUser->setText("root");
    ui->txtPwd->setText("moonpie");



}

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



void LoginDialog::on_btnCancel_clicked()
{
    TryAgain=false;
    close();
}

void LoginDialog::on_btnLogin_clicked()
{
    QString user,pwd;
    QSqlDatabase db;
    user=ui->txtUser->text();
    pwd=ui->txtPwd->text();
    bool loggedIn=false;

    qDebug() << "inside createConnection";
    db = QSqlDatabase::addDatabase("QMYSQL");
    QString connection;
    connection = db.connectionName();
    db.setHostName("localhost");
    db.setDatabaseName("mydb");
    db.setUserName(user);
    db.setPassword(pwd);



      TryAgain=false;


    if (!db.open()) {

        if (QMessageBox::question(this, "Login Failed",
        "Login Failed Retry?", QMessageBox::Yes, QMessageBox::No) == QMessageBox::Yes)
        {
            loggedIn=false;
            TryAgain=true;
            Abort=false;

        }
        else
        {
            loggedIn=false;
            TryAgain=false;
            Abort=true;
            qDebug() << "LoginDialog Abort==true";

        }

    }
    else
    {
     loggedIn= true;
     Abort = false;
    }



    if (loggedIn==false)
    {

        this->close();
    }
    else
    {
        TryAgain=false;
        this->close();





    }

qDebug() << "LoginDialog End of Login doialog";
if (TryAgain==true)
    qDebug() << "LoginDialog TryAgain==true";
else
    qDebug() << "LoginDialog TryAgain==false";

if (Abort==true)
qDebug() << "LoginDialog Abort==true";
else
    qDebug() << "LoginDialog Abort==false";
}

Here is the Globals.h

C++

#ifndef GLOBALS_H
#define GLOBALS_H

#endif // GLOBALS_H
extern bool TryAgain;
extern bool Abort;

Here is the Globals.cpp

#include "Globals.h"
bool TryAgain=false;
bool Abort=false;

JohnnyG62 · Answer 2 · 2015-12-15T10:44:00

Solution 2

I'm sorry, I'm not sure what you mean by calling accept(), reject(), or done(int r) can you elaborate? Also what does the 100 returned from m_Login->exec() mean? did you mean QDialog::Done ?

Posted 15-Dec-15 10:44am

JohnnyG62

Comments

CHill60 15-Dec-15 16:53pm

If you want to respond to a post then use the "Have a Question or Comment?" link next to it so that the poster is notified. Do not post comments as solutions

JohnnyG62 15-Dec-15 23:38pm

Okay. thanks for the tip !

I'm sorry, I'm not sure what you mean by calling accept(), reject(), or done(int r) can you elaborate? Also what does the 100 returned from m_Login->exec() mean? did you mean QDialog::Done ?

Jochen Arndt · Answer 3 · 2015-12-15T21:47:00

This is not a solution for the initial question but a better approach then provided by solution 1 and explains what I said in my comment to that solution:

Quote:
This is a bad solution because it uses global variables instead of dialog return values.

In your LoginDialog call accept(), reject(), or done(int r) according to the result like (these will also close the dialog):
accept() or done (QDialog::Accepted): Logged in
reject() or done (QDialog::Rejected): Not logged, no abort
done(100): Not logged in, abort

In your main window check the value returned by m_Login->exec(). It is QDialog::Accepted, QDialog::Rejected, or 100.

The '100' return code is just an example. In the below code I use QDialogQMessageBox::Retry instead.

The login dialog:

// This may be removed when using the default handling (connecting Cancel button to reject())
void LoginDialog::on_btnCancel_clicked()
{
    reject();
}
 
void LoginDialog::on_btnLogin_clicked()
{
    // trying to open database
    if (!db.open()) {
         if (QMessageBox::question(this, "Login Failed",
        "Login Failed Retry?", QMessageBox::Yes, QMessageBox::No) == QMessageBox::Yes)
        {
            done(QMessageBox::Retry);
        }
        else
        {
            reject(); // same as done(QDialog::Rejected)
        }
    }
    else
    {
        accept(); // same as done(QDialog::Accepted)
    }
 }

The MainWindow function:

void MainWindow::showDialog()
{
    this->hide();
    int result = QMessageBox::Retry;
    while (result == QMessageBox::Retry)
    {
        LoginDialog *login = new LoginDialog(this);
        result = login->exec();
    // EDIT: Delete dialog here if it has not been created with  Qt::WA_DeleteOnClose
        delete login;
    }
    if (result == QDialog::Rejected)
        qApp->closeAllWindows();
    else 
        this->show();
}

[UPDATE]
An even better solution would be to handle retry inside the login dialog:

void LoginDialog::on_btnLogin_clicked()
{
    // trying to open database
    if (!db.open()) {
         if (QMessageBox::question(this, "Login Failed",
        "Login Failed Retry?", QMessageBox::Yes, QMessageBox::No) == QMessageBox::Yes)
        {
            // Retry: Let the dialog stay open.
            // Optionally clear the input fields here.
            return;
        }
        // Let exec() return with QDialog::Rejected
        reject();
    }
    else
    {
        // Let exec() return with QDialog::Accepted
        accept();
    }
}

The corresponding MainWindow function:

void MainWindow::showDialog()
{
    this->hide();
    LoginDialog *login = new LoginDialog(this);
    int result = login->exec();
    // Delete dialog here if it has not been created with  Qt::WA_DeleteOnClose
    delete login;
    if (result == QDialog::Rejected)
        qApp->closeAllWindows();
    else 
        this->show();
}

How to Close QApplication from MainWindow

3 solutions

Solution 1

Solution 2

Solution 3

Add your solution here

Preview 0