How to emit signal using a QString?

[SPlatten]

I have a signal name thats passed in a QString, is there a way to emit the signal using the content of the QString, e.g. my string contains the name of the signal:

    QString strSignal("jsonTextChanged");

I want to use this to emit a signal:

    emit strSignal(parameters);

[jsulm]

@SPlatten said in How to emit signal using a QString?:

emit strSignal(parameters);

Not in C++.
Use https://doc.qt.io/qt-5/qmetaobject.html#invokeMethod

[SPlatten]

Thank you, I'm having difficulty using this:

    QMetaObject::invokeMethod(pobjOriginator
                             ,objcpyJSON[clsXMLnode::mscszAttrSignal]
                             ,Qt::DirectConnection, Q_ARG(QJsonObject, objcpyJSON));

pobjOriginator is a pointer to my class that is derived from QObject.
mscszAttrSignal contains "signal"
objcpyJSON contains a signal string that contains "jsonTextChanged"
The prototype for this signal is:

    void jsonTextChanged(QJsonObject objJSON);

The message displayed in Qt Creator to the right of the invokeMethod call is:

    no matching function for call to 'invokeMethod'

[jsulm]

@SPlatten What type is objcpyJSON?
"mscszAttrSignal contains "signal"" - what does that mean? Do you mean mscszAttrSignal is a signal?
Please post the whole error message, I guess there is no such overload of invokeMethod...

[J.Hilk]

@SPlatten

This does work for me

connect(this, &MainWindow::mySignal, this, [=]()->void{qDebug() << " Tada";});
    QString string("mySignal");

    QMetaObject::invokeMethod(this, string.toLocal8Bit());

Is this what you're looking for?

[SPlatten]

objcpyJSON:

    QJsonObject objcpyJSON(*pobjJSON);
    objcpyJSON.insert(clsXMLnode::mscszAttrSubscriberID, strIDandAttr);

Its a copy of a passed in object of the same type with an additional member added:

clsXMLnode::mscszAttrSubscriberID is a char array containing "sid"

objcpyJSON contains:

    "id"        txted1            QJsonValue (String)
    "sid"       win2:title        QJsonValue (String)
    "signal"    jsonTextChanged   QJsonValue (String)
    "text"      simon             QJsonValue (String)

[Bonnie]

I'm guessing objcpyJSON is a QJsonObject , and objcpyJSON[clsXMLnode::mscszAttrSignal] should be a string of the signal name?

QMetaObject::invokeMethod(pobjOriginator
                          , objcpyJSON[clsXMLnode::mscszAttrSignal].toString().toUtf8()
                          , Q_ARG(QJsonObject, objcpyJSON));

[jsulm]

@SPlatten said in How to emit signal using a QString?:

QJsonObject objcpyJSON(*pobjJSON)

Please read the documentation for invokeMethod -it does not have an overload which takes a QJsonObject as parameter...
See what @Bonnie wrote.

[SPlatten]

Thank you, @Bonnie, this works:

    QJsonObject objcpyJSON(*pobjJSON);
    objcpyJSON.insert(clsXMLnode::mscszAttrSubscriberID, strIDandAttr);
    QMetaObject::invokeMethod(pobjOriginator->pobjGetWidget()
                             ,objcpyJSON[clsXMLnode::mscszAttrSignal].toString().toUtf8()
                             ,Q_ARG(QJsonObject, objcpyJSON));