QDialog not calling MainWindow function

Question

The following code should call MainWindow function but it is not calling it. I am using QT IDE.

#include "itemdialog.h"
#include "ui_itemdialog.h"
#include "mainwindow.h"

ItemDialog::ItemDialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::ItemDialog)
{
    ui->setupUi(this);
    setWindowTitle("Status Dialog");

}

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

void ItemDialog::on_pushButton_clicked()
{
    MainWindow *obj=new MainWindow;
    obj->okbuttonclicked(ui->lineEdit->text());
}

the okbuttonclicked() function is implemented in MainWindow.This Dialog is not supposed to open a new Window. Its function is just to return the input taken from user to MainWindow function.

What is problem in this code. Please Help!

Have you tried fire: obj->show() after obj->okbuttonclicked[...]? — neciu, Mar 06 '12 at 13:26
Why should i call obj->show(), the window is already open. This dialog box is there just to take input from user and then pass it to MainWindow function inorder to take further actions.. — scorpion, Mar 06 '12 at 13:29
Is your code supposed to create a new main window when a dialog button is pressed...? — cmannett85, Mar 06 '12 at 13:33
no. The window is already open. This dialog is a child of the MainWindow — scorpion, Mar 06 '12 at 13:34
Then why are you creating a new one `MainWindow *obj=new MainWindow;`? — cmannett85, Mar 06 '12 at 13:36
I have tried it obj.okbuttonclicked() way also. but it also doesn't return input from dialog box to MainWindow. — scorpion, Mar 06 '12 at 13:37
Try (in your dialog) get parent, cast it on MainWindow and then fire method. — neciu, Mar 06 '12 at 13:40
Are you calling a main window's function from a dialog? Why? Even if you did it correctly, this is still a bad practice. — pnezis, Mar 06 '12 at 13:40
Just wonder, why you thought that "new" will somehow get "old" window? — Kamil Klimek, Mar 06 '12 at 14:29

score 2 · Answer 1 · answered Mar 06 '12 at 13:46

This looks like a horrible attempt at implementing an input dialog. You should emit a signal acknowledging that the user has made an input, and connect that signal to a proper slot in your MainWindow and connect that signal and slot in your MainWindow's constructor. Furthermore, if you are just getting a single string in a modal dialog, you should not reinvent the wheel but use QInputDialog instead.

score 1 · Answer 2 · answered Mar 06 '12 at 13:41

1

You are creating a new (invisible) main window, and calling okbuttonclicked() on that instead of the one already opened. You need to pass the existing QMainWindow into the dialog box, if it is modal this should be done by using it as the dialogs parent. Otherwise create a new constructor arg to carry it.

answered Mar 06 '12 at 13:41

cmannett85

21,725
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i have passed Qmainwindow as parent of Qdialog. Now how can i use parent(Qmainwindow) to call its function. can you please tell me with coding – scorpion Mar 06 '12 at 13:46
Koying has shown you in his answer. But teukkam's answer is a more appropriate fix. – cmannett85 Mar 06 '12 at 13:48

score 0 · Answer 3 · answered Mar 06 '12 at 13:46

0

Dirty, but if your QMainWindow is the parent of your QDialog, you could do:

void ItemDialog::on_pushButton_clicked()
{
    MainWindow *obj=qobject_cast<QMainWindow*>(parent());
    if (obj)
        obj->okbuttonclicked(ui->lineEdit->text());
}

answered Mar 06 '12 at 13:46

Chris Browet

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QDialog not calling MainWindow function

3 Answers3