[solved] Preventing binding-loops is inconvenient

  • I'm building a desktop-application with Qt and I may overlook something but that's how I prevent binding-loops.
    Let's take an editable TextField for example:

    @ TextField {
    id: twitterCustomMessage
    enabled: cppInterface.twitterConnected
    text: cppInterface.twitterCustomMessage
    onTextChanged: cppInterface.setTwitterCustomMessage(twitterCustomMessage.text,false)
    width: 200

    I need to bind it's text-attribute to an actual Q_PROPERTY. To be able to react upon the user entering text I have to link onTextChanged to an INVOKABLE method. Here I use the set-method of the Q_PROPERTY which looks like this:

    @void QmlCppMediator::setTwitterCustomMessage(QString value, bool emitSignal){
    m_twitterCustomMessage = value;

    if (emitSignal){
        emit twitterCustomMessageChanged();
    else {
        emit twitterCustomMessageSaveSignal();


    I had to add the seconds parameter so it wouldn't cause a binding-loop. I also had to add another signal I can connect to a slot of the parent-class of the whole qml-cpp-mediator thing.

    The easier method would be having another method emitting twitterCustomMessageSaveSignal but this is still a lot.

    Does anyone have suggestion to simplify this process?

  • Moderators

    http://developer.qt.nokia.com/forums/viewthread/1779/ claims that doing the setter method properly will stop the warning.

  • Thank you.

    That is a much smarter way of handling it.

    Congratulations to your 1000th post as well.

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