Undefined reference to `QCheckBox::staticMetaObject'

furest

Hi!

I'm trying to access my QCheckBox from C++ (it's declared in my QML app) but always en up with this error because of this code :

QCheckBox *obj = parent()->findChild<QCheckBox*>("cbThick");
obj->setProperty("checked", (state!=0));

The object trying to call it from has been declared inside QML too (it has a QObject tag).
This is the way I declared the type in QML :

int main(int argc, char *argv[])
{
    qmlRegisterType<ConnectionHandler>("MyHandler", 1, 0, "ConnectionHandler");
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QGuiApplication app(argc, argv);
    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;

    return app.exec();
}

And inside QML :

ConnectionHandler{
        id: ch
        ip: tfIP.text
        port: tfPort.text
    }

I've seen the code I'm trying to compile on multiple places on forums but It seems the way I use it is different though...

Any idea?

Christian Ehrlicher

@furest said in Undefined reference to `QCheckBox::staticMetaObject':

QGuiApplication

QCheckBox is a QWidget so you will likely need to link against QtWidgets and use a QApplication.

furest

Hi!
Thank you a lot! I compiles (I think it must work then...)
A bit of google research helped me (in case any newbie like me has trouble finding out):

Link against widgets : edit your project.pro and add widget to that line, like this:

QT += quick widgets

Then just include QApplication in your main.cpp:

#include <QApplication>

And change your QGuiApplication app to a QApplication app