How do I use my own subclass in the ui?

lansing

I have extended the QDoubleSpinBox to my own subclass MySpinBox, then I created a doublespinbox object in the ui designer and promoted it to use MySpinBox class. But when I ran it, it gave me this long error:

mainwindow.obj:-1: error: LNK2019: unresolved external symbol "public: __cdecl MySpinBox::MySpinBox(class QWidget *)" (??0MySpinBox@@QEAA@PEAVQWidget@@@Z) referenced in function "public: void __cdecl Ui_MainWindow::setupUi(class QMainWindow *)" (?setupUi@Ui_MainWindow@@QEAAXPEAVQMainWindow@@@Z)

This is my files.

my_spinbox.h

#ifndef MY_SPINBOX_H
#define MY_SPINBOX_H

#include <QDoubleSpinBox>

class MySpinBox: public QDoubleSpinBox
{
    Q_OBJECT

public:
    MySpinBox(QWidget *parent = nullptr);

};

#endif // MY_SPINBOX_H

my_spinbox.cpp

#include "my_spinbox.h"

MySpinBox::MySpinBox(QWidget *parent): QDoubleSpinBox(parent)
{
}

What is wrong?

hskoglund

Hi, in your .pro file, check if you have

HEADERS += my_spinbox.h
SOURCES += my_spinbox.cpp

mrjj

Hi
Also sometimes it can be a bit happy to cache files
so if you have headers as @hskoglund says then
go and delete your build folder and run qmake and rebuild all.

lansing

@mrjj Thank you, that's the problem. I deleted the build folder and rebuild it again and it works.