Using QCommandLineParser with QGuiApplication

[akshaybabloo]

I am trying to add a CLI to my existing GUI application, but whenever I use, for example, --version a dialog window opens up instead of writing the text in terminal. Here is the main code:

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QCommandLineParser>
#include <iostream>

int main(int argc, char *argv[]) {
    QGuiApplication app(argc, argv);

#ifdef APP_VERSION
    QCoreApplication::setApplicationVersion(QString(APP_VERSION));
#else
    QCoreApplication::setApplicationVersion(QString("dev"));
#endif

    QCoreApplication::setApplicationName(QCoreApplication::translate("gav",
                                                                     "GAV is a simple audio and video player, backed by FFmpeg and Qt6"));

    QCommandLineParser parser;
    parser.setApplicationDescription("GAV is a simple audio and video player, backed by FFmpeg and Qt6");
    parser.addHelpOption();
    parser.addVersionOption();

    QCommandLineOption sourceOption("source", "Source of the audio or video to play");
    parser.addOption(sourceOption);

    parser.process(app);

    QString sourceValue;
    if (parser.isSet(sourceOption)) {
        sourceValue = parser.value(sourceOption);
    }

    QQmlApplicationEngine engine;
    if (!sourceValue.isEmpty()) {
        QUrl sourceURL = QUrl::fromUserInput(sourceValue);
        if (!sourceURL.isEmpty() && sourceURL.isValid())
            engine.setInitialProperties({{"source", sourceURL}});
    }

    QObject::connect(
        &engine,
        &QQmlApplicationEngine::objectCreationFailed,
        &app,
        []() { QCoreApplication::exit(-1); },
        Qt::QueuedConnection);

    if (!parser.isSet("version") || !parser.isSet("help")) {
        engine.loadFromModule("gavqml", "Main");
    }

    return app.exec();
}

I tried to do this:

if (!parser.isSet("version") || !parser.isSet("help")) {
        engine.loadFromModule("gavqml", "Main");
    }

So that the engine doesn't load the qml, but the dialog still shows up.

What is the correct way of doing this?

[Bonnie]

It will always pop a message box if your application doesn't have an attached console, which is the normal case when running a gui application on Windows, even started from console.
(From Qt's internal source code, the message box could be avoid by setting enviroment variable "QT_COMMAND_LINE_PARSER_NO_GUI_MESSAGE_BOXES" but still there won't be text written to console since none is attached.)
You need to configure your project to be a console application so that it will automatically attach the console, but this will bring a new problem: when running the applicaion by double clicking, it will also open a console window (with GUI window). In order to solve that you'll need to find a way to know it is started from console or not, if not, close the console. That's a little complicated, normally windows GUI applications just don't have CLI for console/terminal.
If you are interested, here is how Qt installer checks whether started from console or not:
https://github.com/qtproject/installer-framework/blob/master/src/sdk/main.cpp#L352

[akshaybabloo]

That's really helpful. thank you.