Object::connect: No such signal

Christian Ehrlicher

@Risver said in Object::connect: No such signal:

connect(&logWindow, SIGNAL(loginSucces()), this, SLOT(nextWindow()));

There is no such signal in your Login class:

signals:
void LoginSuccess();

and btw:

{
ui->setupUi(this);
setWindowFlags(Qt::MSWindowsFixedSizeDialogHint);
login logWindow;
connect(&logWindow, SIGNAL(loginSucces()), this, SLOT(nextWindow()));
}

How long does your local variable logWindow live and how should this work?

raven-worx

@Risver said in Object::connect: No such signal:

login logWindow;
connect(&logWindow, SIGNAL(loginSucces()), this, SLOT(nextWindow()));

compare the signal name and you will see
never create a widget on the stack, it will be deleted right after when the variable goes out of scope

JonB

@Risver said in Object::connect: No such signal:

connect(&logWindow, SIGNAL(loginSucces()), this, SLOT(nextWindow()));

In addition to the above answers which you need to act on. Please do yourself a favour and switch over to using New Signal Slot Syntax, instead of the SIGNAL/SLOT() macros. You would then get compile-time errors instead of the runtime ones you get now.

Risver

@Christian-Ehrlicher said in Object::connect: No such signal:

@Risver said in Object::connect: No such signal:
connect(&logWindow, SIGNAL(loginSucces()), this, SLOT(nextWindow()));
There is no such signal in your Login class:

signals:
void LoginSuccess();

and btw:

{
ui->setupUi(this);
setWindowFlags(Qt::MSWindowsFixedSizeDialogHint);
login logWindow;
connect(&logWindow, SIGNAL(loginSucces()), this, SLOT(nextWindow()));
}

How long does your local variable logWindow live and how should this work?

Ohh, i did a mistake in the name, but now i corrected the signal name and it still not working.
The variable 'logWindow' is only for reference to login class.

J.Hilk

@Risver said in Object::connect: No such signal:

The variable 'logWindow' is only for reference to login class.

no, that's not how c++ works!

the way you wrote it, its a new local instance of the class, that, because its on the stack, will be destroyed as soon as the program code hits the } of the constructor

Risver

@J-Hilk said in Object::connect: No such signal:

@Risver said in Object::connect: No such signal:

The variable 'logWindow' is only for reference to login class.

no, that's not how c++ works!

the way you wrote it, its a new local instance of the class, that, because its on the stack, will be destroyed as soon as the program code hits the } of the constructor

How should i refer to this class, so that the variable is not deleted ?

J.Hilk

@Risver

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QObject>
#include <QMainWindow>

#include "signup.h"
#include "login.h"

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

public slots:
    void nextWindow();

private slots:
    void on_login_clicked();
    void on_signup_clicked();

private:
    Ui::MainWindow *ui;
    Login *m_logWindow{nullptr}; // m_ prefix so we see its a member variable of the class
};

#include "mainwindow.h"
#include "ui_mainwindow.h"


MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this); 
    setWindowFlags(Qt::MSWindowsFixedSizeDialogHint);
    m_logWindow = new Login(this); //I assume Login is a Widget at heart so we pass on parent so that Qt manages the memory for us
    //connect(m_logWindow, SIGNAL(loginSucces()), this, SLOT(nextWindow()));
    connect(m_logWindow,&Login::loginSucces, this, &MainWindow::nextWindow); // Better use the new syntax
}

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

void MainWindow::on_login_clicked()
{
    m_logWindow->show();
}

void MainWindow::on_signup_clicked()
{
    signup * signupWindow = new signup();
    signupWindow->show();
}

void MainWindow::nextWindow()
{
    ui->stackedWidget->setCurrentIndex(1);
}

Risver

@J-Hilk said in Object::connect: No such signal:

connect(m_logWindow,&Login::loginSucces, this, &MainWindow::nextWindow);

I did as you said and now i have :

no matching member function for call to 'connect'

candidate function [with Func1 = void (login::*)(), Func2 = void (MainWindow::*)()] not viable: no known conversion from 'login' to 'const typename QtPrivate::FunctionPointer<void (login::*)()>::Object *' (aka 'const login *') for 1st argument; take the address of the argument with &

candidate function not viable: no known conversion from 'login' to 'const QObject *' for 1st argument; take the address of the argument with &

no matching function for call to 'MainWindow::connect(login&, void (login::*)(), MainWindow*, void (MainWindow::*)())'
../DiffPassV2/mainwindow.cpp: In constructor 'MainWindow::MainWindow(QWidget*)':
../DiffPassV2/mainwindow.cpp:11:76: error: no matching function for call to 'MainWindow::connect(login&, void (login::*)(), MainWindow*, void (MainWindow::*)())'
     connect(m_logWindow,&login::LoginSuccess, this, &MainWindow::nextWindow);

etc.

Christian Ehrlicher

@Risver said in Object::connect: No such signal:

m_logWindow

This should be a pointer but it's not in your code.

J.Hilk

@Risver My bad

I actually forgot the pointer....

//in mainwindow.h
 Login *m_logWindow{nullptr};

Risver

@Christian-Ehrlicher said in Object::connect: No such signal:

@Risver said in Object::connect: No such signal:

m_logWindow

This should be a pointer but it's not in your code.

Thanks now i have no errors, but it is not switching between the stacked widgets

~~Sorry, that i don't reply faster but i have a 600s limit~~
Thanks J.Hilk

J.Hilk

@Risver please post your changed code now :D

jsulm

@Risver So, was MainWindow::nextWindow() called? Was loginSucces signal emitted?

Risver

@J-Hilk

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QObject>
#include <QMainWindow>

#include "signup.h"
#include "login.h"

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

public slots:
    void nextWindow();

private slots:
    void on_login_clicked();
    void on_signup_clicked();

private:
    Ui::MainWindow *ui;
    login * m_logWindow{nullptr};
};
#endif // MAINWINDOW_H

#include "mainwindow.h"
#include "ui_mainwindow.h"


MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this); 
    setWindowFlags(Qt::MSWindowsFixedSizeDialogHint);
    m_logWindow = new login(this);
    connect(m_logWindow,&login::LoginSuccess, this, &MainWindow::nextWindow);
}

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

void MainWindow::on_login_clicked()
{
    login * loginWindow = new login();
    loginWindow->show();
}

void MainWindow::on_signup_clicked()
{
    signup * signupWindow = new signup();
    signupWindow->show();
}

void MainWindow::nextWindow()
{
    ui->stackedWidget->setCurrentIndex(1);
}

#ifndef LOGIN_H
#define LOGIN_H

#include <QDialog>
#include <QPoint>
#include <QObject>
#include <QMouseEvent>

#include "mainwindow.h"

namespace Ui {
class login;
}

class login : public QDialog
{
    Q_OBJECT

public:
    explicit login(QWidget *parent = nullptr);
    ~login();

private slots:
    void on_exit_clicked();

    void on_pushButton_clicked();

private:
    Ui::login *ui;

    void mousePressEvent(QMouseEvent *event);
    void mouseMoveEvent(QMouseEvent *event);
    int m_nMouseClick_X_Coordinate;
    int m_nMouseClick_Y_Coordinate;

signals:
    void LoginSuccess();
};

#endif // LOGIN_H

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

#include <QMessageBox>


login::login(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::login)
{
    ui->setupUi(this);
    setWindowFlags(Qt::Window | Qt::FramelessWindowHint);
    setAttribute(Qt::WA_TranslucentBackground);
    setAttribute(Qt::WA_TransparentForMouseEvents);
}

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

void login::mousePressEvent(QMouseEvent *event)
{
    m_nMouseClick_X_Coordinate = event->position().x();
    m_nMouseClick_Y_Coordinate = event->position().y();
}

void login::mouseMoveEvent(QMouseEvent *event)
{
    move(event->globalPosition().x() - m_nMouseClick_X_Coordinate, event->globalPosition().y() - m_nMouseClick_Y_Coordinate);
}

void login::on_exit_clicked()
{
    this->close();
}

void login::on_pushButton_clicked()
{
    dbManager db;

    QString username = ui->username->text();
    QString password = ui->password->text();

    db.Login(username, password);
    if(db.log < 1)
        QMessageBox::about(this, "error", "Your login or password is not correct");
    if(db.log == 1)
    {
        QMessageBox::about(this, "login", "Login successful");
        emit LoginSuccess();
        this->close();
    }
}

Risver

@jsulm said in Object::connect: No such signal:

@Risver So, was MainWindow::nextWindow() called? Was loginSucces signal emitted?

~~I will check~~
No, it wasn't

J.Hilk

@Risver

see
you didn't change this function

void MainWindow::on_login_clicked()
{
    login * loginWindow = new login();
    loginWindow->show();
}

thats the same error as in the constructor, use the member instance

void MainWindow::on_login_clicked()
{
    m_logWindow->show();
}

Risver

@J-Hilk said in Object::connect: No such signal:

m_logWindow->show();

It works very well, thank you all for the help :)

Bangash

There is another way, you may try;
Mainwindow.h
public slotExit();

and same time includes such lines in Mainwindow.cpp
void MainWindow::slotExit()
{
qApp->exit();
}

try it, Good Luck