QMetaObject::connectSlotsByName: No matching signal for on_pushButton_clicked()

[RajeevSahu]

Hi friends,

I am working on a GUI project. I have 2 .ui files mainwindow.ui and mapsmainwindow.ui.

My main.cpp contains the folowing etails:

#include <QtGui/QApplication>
#include "mainwindow.h"
int main(int argc, char *argv[])
{    
    QApplication a(argc, argv);
    MainWindow w;
    #if defined(Q_WS_S60)
       w.showMaximized();
    #else
        w.show();
    #endif

    return a.exec();
}

mainwindow.h contains:

public Q_SLOTS: //slots to receive action of menu trigger.
   void ShowAction();
private slots:
    void on_pushButton_clicked();

In mainwindow.cpp I am trying to use the following 2 functions like :

void MainWindow::ShowAction()
{

    MapsMainWindow w;//Loads mapsmainwindow.ui
    #if defined(Q_WS_S60)
        w.showMaximized();////mapsmainwindow.ui displayed in maximized mode
    #else
        w.show();
    #endif
}

void MainWindow::on_pushButton_clicked()
{
    ShowingAction();
}

With above implementations I am able to Build successfully, but when the application is installed on device, it is giving warnings every time i clicked the pushButton and nothing happens:

Warnings are like:

[Qt Message] QMetaObject::connectSlotsByName: No matching signal for on_pushButton_clicked()
[Qt Message] QMetaObject::connectSlotsByName: No matching signal for on_pushButton_clicked()

Please guide me on this issue.

Thanks...

[divanov]

Do you set "pushButton" name for your button?
http://doc.trolltech.com/4.6/qobject...bjectName-prop

[RajeevSahu]

yes.
ui_mainwindow.hcontains this button.

class Ui_MainWindow
{
public:
QWidget *centralWidget;
QPushButton *pushButton;

void setupUi(QMainWindow *MainWindow)
{
if (MainWindow->objectName().isEmpty())
MainWindow->setObjectName(QString::fromUtf8("MainWindow"));
MainWindow->resize(469, 640);
centralWidget = new QWidget(MainWindow);
centralWidget->setObjectName(QString::fromUtf8("centralWidget"));
centralWidget->setEnabled(true);
pushButton = new QPushButton(centralWidget);
pushButton->setObjectName(QString::fromUtf8("pushButton"));
pushButton->setGeometry(QRect(150, 320, 101, 41));
MainWindow->setCentralWidget(centralWidget);
pushButton->raise();

retranslateUi(MainWindow);

QMetaObject::connectSlotsByName(MainWindow);
} // setupUi

[danhicksbyron]

Where are your connect() statements?

[divanov]

This is really strange. Can you share the whole project?

[divanov]

Where are your connect() statements?

QMetaObject::connectSlotsByName is used instead.

[danhicksbyron]

I'm guessing it can't be a private slot and be connected from another object. It can be private and have MainWindow execute a connect(), however.

[RajeevSahu]

Where are your connect() statements?

I don't have any connect statements!!!

[RajeevSahu]

QMetaObject::connectSlotsByName is used instead.

ui_mainwindow.hcontains this.

[RajeevSahu]

I'm guessing it can't be a private slot and be connected from another object. It can be private and have MainWindow execute a connect(), however.

I made it public but same thing happens:

[Qt Message] QMetaObject::connectSlotsByName: No matching signal for on_pushButton_clicked()

[RajeevSahu]

Hey...

Little update on this issue.

In mainwindow.cpp I have changed the following 2 functions like :

void MainWindow::ShowAction()
{

/*MapsMainWindow w;//Loads mapsmainwindow.ui
#if defined(Q_WS_S60)
w.showMaximized();////mapsmainwindow.ui displayed in maximized mode
#else
w.show();
#endif*/
QMessageBox msgBox;
msgBox.setInformativeText("slot executed...");
msgBox.setStandardButtons(QMessageBox::Ok);
int ret = msgBox.exec();
}

void MainWindow:n_pushButton_clicked()
{
ShowingAction();
}

The above code is executed and message is displayed when I click the Button. How ever When I tried to call another UI (

MapsMainWindow w; w.showMaximized();

) it is giving the warning explained before.

[Qt Message] QMetaObject::connectSlotsByName: No matching signal for on_pushButton_clicked()

Why is this thing happening....Is there any differentiation between the 2 implementations in the

void MainWindow::ShowAction()

function?

[divanov]

The reason for this message is that you have an object with slot on_pushButton_clicked and this object doesn't have an object with name pushButton among its children or this object doesn't have clicked signal.

[RajeevSahu]

The reason for this message is that you have an object with slot on_pushButton_clicked and this object doesn't have an object with name pushButton among its children or this object doesn't have clicked signal.

Ok divanov,

then how can I call another UI window by a button click. Do I need to do some thing extra to load another window like the follow piece of code?

MapsMainWindow w;//Loads mapsmainwindow.ui
w.showMaximized();////mapsmainwindow.ui displayed in maximized mode

[divanov]

then how can I call another UI window by a button click.

One of the possible solutions:
http://wiki.forum.nokia.com/index.ph...ows_in_Maemo_5

[RajeevSahu]

One of the possible solutions:
http://wiki.forum.nokia.com/index.ph...ows_in_Maemo_5

Hey...

I have tried as per the link provided by You but I am getting one error like:

undefined reference to `MainScreen::MainScreen(QWidget*)'

The file contents are as follows:

mainwindow.h..............

#include <QMainWindow>
#include "screen.h"
namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

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

private:
Ui::MainWindow *ui;

private:
void CreateButton();

private slots:
void buttonClicked(bool checked = false);
void windowDestroyed(QObject* obj = 0);

private:
MainScreen *mainScreen;
};

mainwindow.cpp........

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

#include <QMessageBox>
#include <QPushButton>
#include <QDebug>
//#include "screen.h"

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),mainScreen(0),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
setWindowTitle("DisplayMyWindow");
CreateButton();
}

void MainWindow::buttonClicked(bool checked)
{
Q_UNUSED(checked);

if (!mainScreen) {
mainScreen = new MainScreen(this);
mainScreen ->setAttribute(Qt::WA_DeleteOnClose);
connect(mainScreen, SIGNAL(destroyed(QObject*)),this, SLOT(windowDestroyed(QObject*)));
mainScreen->showMaximized();
qDebug() << "Show Map" << mainScreen;
}
}
void MainWindow::windowDestroyed(QObject* obj)
{
disconnect(obj, SIGNAL(destroyed(QObject*)),this, SLOT(windowDestroyed(QObject*)));
qDebug() << "No Show Map" << mainScreen;
}

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

void MainWindow::CreateButton()
{
QPushButton *startmapBtn = new QPushButton();
startmapBtn->setText("MapStart");
startmapBtn->setGeometry(QRect(150, 400, 135, 50));
connect(startmapBtn, SIGNAL(clicked(bool)), this, SLOT(buttonClicked(bool)));
}

screen.h......

#include "ui_showmap.h"
#include <QtGui>
#include <QWidget>
#include <QWebView>
#include <QStandardItemModel>

class MainScreen : public QWidget ,public Ui::Form
{
Q_OBJECT
public :
MainScreen(QWidget *parent=0);

public slots :
void on_button1_clicked();
};

screen.cpp......

#include "screen.h"
#include "ui_showmap.h"
#include <QWebView>
#include <QHeaderView>
#include <QWebFrame>
#include <QWebPage>

MainScreen::MainScreen(QWidget *parent):QWidget(parent)
{
setupUi(this);
//map->load(QUrl("http://www.trolltech.com/"));
//map->load(QUrl("./index.html") ) ;
}

void MainScreen:n_button1_clicked()
{
//map->clearCoordinates();
//map->geoCode("Campina Grande");
}

Please help me to figure out the problem!