passing signal with parameters from qml to c++

Question

I dont know how to pass parameters from QML file to c++ file in Qt.

QML code:

import QtQuick 1.1

Rectangle{
    id:loin
    height: 272
    width:480
    property alias loguid:loginuid
    signal sigHome()
    Rectangle{
        id:rect1
        width:parent.width-80
        height:24
        TextInput {
            id:loginuid
            maximumLength: 16
            width: maximumLength * 20
            focus: false
            validator: RegExpValidator { regExp: /\d+/ }
            KeyNavigation.down: login1
        }
    }
    Button{
        id: login1
        x: 195
        y: 187
        height:30;
        focus:false
        border.color:"black"
        opacity: activeFocus ? 1.0 : 0.5
        Text{
        text:"LOGIN"
            anchors.horizontalCenter:login1.horizontalCenter;
            anchors.verticalCenter:login1.verticalCenter;
        }
        Keys.onReturnPressed: {
             if(loginuid.text  <  1000000000000000)
             {
                 text1.opacity=0.1
                 error1.visible=true
                 errorText.text="\n enter valid 16 digit number\n"
                 errorOk.focus=true
                 loginuid.focus=false
             }
             else{
                 loginuid.focus=false
                 loin.sigHome()
             }
        }
    }
}

c++ code:

#include <QApplication>
#include <QDeclarativeView>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    int uid;
    QDeclarativeView view;
    view.setSource(QUrl::fromLocalFile("main.qml"));
    view.show();
    return app.exec();
}

When I press the login button rect1.text content shud go to main.cpp file and uid in the main.cpp get dat value. Something like this uid=rect1.text.
How to do it?

Answer 1

I wouldn't try to listen for a QML signal from the C++ side. Calling a C++ method with arguments is much easier and achieves the same:

To do so you have to:

• define a slot or invokable method accepting the required arguments
• register the class carrying the method with the declarative engine
• then you can set an instance of this class as a property of your root context and finally call this method from QML

This topic is also well covered in the official documentation.