Why my data can not transfer between forms with SIGNAl/SLOT? - c++

Question

I have main window and 1 dialog in Qt(in Linux OS).I want to send some thing from main window to my dialogs. When the user press menu button, then my button clicked emit a signals. this is my code in main.cpp:
MainWindow w;
MyDialog m;
//------------------------------
//this connection send key button press mood from MainWindow
QObject::connect(&w,SIGNAL(pressMood(QString)),
&m,SLOT(getPressMood(QString)));
w.show();
and this is my mainwindos.h:
signals:
void pressMood(QString mood) ;
mainwindow.cpp:
void MainWindow::on_btnMenu_clicked()
{
if(database->checkEmpty())
{
menu mn;/*=new menu();*/
mn.showFullScreen();
}
else
{
MyDialog *d=new MyDialog(this);
d->show();
d->raise();
d->activateWindow();
emit pressMood("menu");
if(d->Accepted>0)
{
if(loginResult)
{
menu *mn=new menu();
mn->showFullScreen();
}
}
else
QMessageBox::warning(this, tr("Login failed"), "Sorry.Your authenticate is not valid.", QMessageBox::Ok);
}
}
//--------------------------------------------
void MainWindow::on_btnPassword_clicked()
{
//emit sendID2(result);
CardDialog *d=new CardDialog(this);
emit pressMood("pass");
d->show();
d->raise();
if(d->Accepted<=0)
QMessageBox::warning(this, tr("Login failed"), "Sorry.Your authenticate is not valid.", QMessageBox::Ok);
}
I do not use dialog.exec() because I do not need to show modal.
MyDialog.h:
public slots:
void getPressMood(QString mood);
and MyDialog.cpp:
//=================================================
void MyDialog::getPressMood(QString mood)
{
mood=mood;
//ui->lblMood->setText(mood);;
//ui->lblMood->hide();
}
void MyDialog::on_buttonBox_accepted()
{
//QString mood=ui->lblMood->text();
bool st=database->checkPassword(ui->txtID->text(),ui->txtPass->text(),"3");
int id=(ui->txtID->text()).toInt();
//this user is valid to go to menu page
//s/he is admin
if((st)&&
mood=="menu" &&
database->checkAdmin(id))
{
.......
}
when I trace my code line by line. the emit signal is works , it sends the string data to my slot in another form and also the getpressedmood() slot is also worked. But the global var mood become NULL when the dialog show, also I decide to save data in label. In trace mood I see the string is send but when the dialog shows the label becomes to default value.
I can not find the mistake. Could you help me?

Answer 1

It solved.
my mistake is connect the signal and slot in main.cpp. The answer is :
MyDialog *d=new MyDialog(this);
//should connect here not in main.cpp
QObject::connect(this,SIGNAL(pressMood(QString)),
d,SLOT(getPressMood(QString)));
emit pressMood("menu");
d->show();
d->raise();
d->activateWindow();