Link slot in C++ to signal in QML

Lordful

Hello,

I'm learning Qt/QML and I'm in troubles about linking a slot C++ to a signal QML. I can't find the way to work with this.

Here is my code

main.cpp

        QQmlApplicationEngine engine;
        engine.rootContext()->setContextProperty("personne",p);
        engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

        QQuickView view(QUrl(QStringLiteral("qrc:/main.qml")));
        QObject *o = view.rootObject();
        
        QObject::connect(o,SIGNAL(),p,SLOT(changedAgain());

personne.h

class Personne : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString firstName READ firstName WRITE setFirstName NOTIFY firstNameChanged)
    Q_PROPERTY(QString lastName READ lastName WRITE setLastName NOTIFY lastNameChanged)

public:
    Q_INVOKABLE bool postMessage(const QString &msg);

    explicit Personne(QObject *parent = 0);

    QString lastName() const;
    void setLastName(const QString &lastName);

    QString firstName() const;
    void setFirstName(const QString &firstName);

signals:
    void firstNameChanged();
    void lastNameChanged();

public slots:
    void changedAgain();

private:
    QString m_firstName;
    QString m_lastName;
};

main.qml

import QtQuick 2.4
import QtQuick.Window 2.2
import QtQuick.Controls 1.1
import cpp.models.person 1.0

Window {
    visible: true

    signal upperTextSignal(string text)

    MouseArea {
        anchors.fill: parent
        onClicked: {
            Qt.quit()
        }
    }

    Personne {
        id: person
        firstName: "John"
        lastName: "Doe"
        onFirstNameChanged: {
            console.log("First name changed. From C++ : " + personne.firstName)
            upperTextSignal(person.firstName)
        }

        onLastNameChanged: {
            console.log("Last name changed.From C++ : "+ personne.firstName)
        }
    }
}

For me, its seems good but I can't access to my signal, which is declared in main.qml, from the main.cpp.

I will appreciate the explination of my mystake.

JKSH

@Lordful said:

QObject::connect(o,SIGNAL(),p,SLOT(changedAgain());

Specify the signal: SIGNAL(upperTextSignal(QString))

See also http://doc.qt.io/qt-5/signalsandslots-syntaxes.html#connecting-c-objects-to-qml-objects

EDIT: Why do you load main.qml 2 times? (Once using QQmlApplicationEngine and once using QQuickView)