Help sending data from dialog to main window

[Cantona]

@JonB

Please can you show a quick guide on how to use signals and slot for this

[JonB]

@Cantona Why, given that I said of signals/slots "but I don't see a need here"? Getter/setter is simpler and better here.

[Cantona]

@JonB

I have never used getter/setter in qt so I don't know how to go about it

[JonB]

@Cantona
You have used it many times, Qt uses this pattern for all its class variables. It's just simple C++ (or Python):

// .h file
class UsernameDialog : public QDialog
{
public:
    const QString &username() const;    // "getter" for username
    void setUsername(const QString &username);    // "setter" for username, probably not used for this case
}

// .cpp file
const QString &UsernameDialog::username() const
{
    return ui->lineEdit.text();
}
void UsernameDialog::setUsername(const QString &username)
{
    ui->lineEdit.setText(username);
}

// mainwindow cpp file
QString username;
UsernameDialog *usernameDialog = new UsernameDialog;
if (usernameDialog->exec())
    username = usernameDialog->username();

[Cantona]

@JonB

Sorry I couldn't get this to work

[SGaist]

Hi,

What exactly did not work now ?

[Cantona]

@SGaist

Everything I guess. D variable username still is not getting any data assigned to it

[Pl45m4]

@Cantona said in Help sending data from dialog to main window:

variable username still is not getting any data assigned to it

Unpleasant answer but no secret or surprise:
You need to know C++ if you want to get somewhere with Qt :)
Learn the basics of C++ and OOP and you will understand better and learn faster how to work with Qt.

@JonB said in Help sending data from dialog to main window:

// mainwindow cpp file
QString username;
UsernameDialog *usernameDialog = new UsernameDialog;
if (usernameDialog->exec())
    username = usernameDialog->username();

This answer by @JonB is basically everything you need to do to return your variable from your dialog and assign it to something within your QMainWindow class.

[alexjordan_now]

@Cantona You can achieve this by emitting a signal from the login dialog and connecting it to a slot in the main window. In LoginDialog, emit a signal like emit sendUsername(username); when the button is clicked. Then, in MainWindow, connect it with connect(loginDialog, &LoginDialog::sendUsername, this, &MainWindow::setUsername);.

Hope these steps help you out!

[Pl45m4]

@alexjordan_now said in Help sending data from dialog to main window:

You can achieve this by emitting a signal from the login dialog and connecting it to a slot in the main window

That's one way that was also already mentioned before :)
Though I think if you want to return one value only, setting up a signal/slot connection is more "work" than just returning the value directly to the caller.