Send array from QML to c++ via signal

[maxwell31]

Hi,

I want to pass an array from QML to C++ via a signal:

signal passArray(variant array)
function emitPassArray() {
    var i
    var array = []
    for(i=0; i<gridView.model.count;i++) {
        var myob =gridView.model.items.get(i).model
        array.push(myob.property1)
    }
    passArray(array)
}

and I thought I catch it on the c++ side with a

    void getArray(QVariantList array);

slot. However, I get the message, that it is not possible to connect getArray as there is no signal passArray(QVariantList). What am I doing wrong?

[maxwell31]

Calling the c++ slot in QML directly is working. Still, I would be interested in how it should be done if one were to use a signal

[dheerendra]

You can expose qlist as qproperty from c++ and set the list in qml. No need pass signal and catch it. Is there a hard requirement to send signal only ?

[raven-worx]

@maxwell31 said in Send array from QML to c++ via signal:

However, I get the message, that it is not possible to connect getArray as there is no signal passArray(QVariantList). What am I doing wrong?

check the output of the following:

const QMetaObject* mo = myQmlObject->metaObject();
for (int i = mo->methodOffset(); i < mo->propertyCount(); ++i) {
        QMetaMethod m = mo->method(i);
        if( m.methodType() != QMetaMethod::Signal )
             continue;
        qDebug() << m.methodSignature();
}

This prints the signatures of all the object's signals.

I guess the signature is just wrong. Since you defined the signal in QML with a variant type, i think the correct parameter type will be QVariant instead.

[JKSH]

@raven-worx said in Send array from QML to c++ via signal:

I guess the signature is just wrong. Since you defined the signal in QML with a variant type, i think the correct parameter type will be QVariant instead.

Indeed. After that, you can convert the data using QVariant::toList().

http://doc.qt.io/qt-5/qtqml-cppintegration-interactqmlfromcpp.html#connecting-to-qml-signals says "When a QML object type is used as a signal parameter, the parameter should use var as the type, and the value should be received in C++ using the QVariant type"

Also, according to http://doc.qt.io/qt-5/qml-variant.html, variant is "obsolete and exists only to support old applications; new applications should use var type properties instead."

[maxwell31]

Yes, the problem was that I used QVariantList on the C++ side instead of QVariant. Thank you all for your help!