Qt: Cannot invoke shared object methods/properties from javascript

Question

I have tried exactly same as the answer of Vicky Chijwani for this question QT QWebEnginePage::setWebChannel() transport object and everything fine but I cant able to invoke any methods or properties of jshelper.

kindly look at my code myclass.h

class MyClass : public QObject
{
    Q_OBJECT
public:
    MyClass(QObject *parent = 0);
    void print();

    int num;

signals:

public slots:
};

myclass.cpp

MyClass::MyClass(QObject *parent) : QObject(parent)
{
 num=100;
}

void MyClass::print()
{
    QMessageBox bx;
    bx.exec();
}

mywebengineview.h

class MyWebEngineView : public QWebEngineView
{
public:
    MyWebEngineView(QWidget *parent);

    MyClass helper;
};

mywebengineview.cpp

MyWebEngineView::MyWebEngineView(QWidget *parent): QWebEngineView(parent)
{
    QWebChannel *channel = new QWebChannel(page());
    channel->registerObject(QStringLiteral("jshelper"), &helper);load(QUrl::fromLocalFile(QFileInfo("../html/index.html").absoluteFilePath()));
    page()->setWebChannel(channel);
}

mainwindow.cpp

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    view = new MyWebEngineView(this);
    view->setGeometry(10, 10, 500, 500);
    view->load(QUrl::fromLocalFile(QFileInfo("../html/index.html").absoluteFilePath()));
}

finally javascript

<script type="text/javascript">
        var jshelper;
        document.addEventListener("DOMContentLoaded", function () {
            new QWebChannel(qt.webChannelTransport, function(channel) {
                alert('ok');
                // all published objects are available in channel.objects under
                // the identifier set in their attached WebChannel.id property

                jshelper = channel.objects.jshelper;
                alert( jshelper.num );
                jshelper.print();

            });
        });

        </script>

The problem is these two lines never executes properly

alert( jshelper.num ); // gives 'undefined' message
jshelper.print(); //will not work

what is wrong with my code, I am trying to fix this issue around 4 days but I couldn't able to fix it.

What does `console.log(channel.objects.jshelper)`, or `console.log(channel.objects)` say? — azium, Sep 25 '15 at 14:31
jshelper:__id__: "jshelper"__objectSignals__: Object__propertyCache__: ObjectdeleteLater: function () {destroyed: Objectconnect: function (callback) {disconnect: function (callback) {__proto__: ObjectobjectName: (...)get objectName: function () {set objectName: function (value) {objectNameChanged: ObjectpropertyUpdate: function (signals, propertyMap)signalEmitted: function (signalName, signalArgs)unwrapProperties: function ()unwrapQObject: function (response)__proto__: QObject — Gilson PJ, Sep 25 '15 at 14:56

score 2 · Accepted Answer · answered Sep 28 '15 at 18:59

2

I know under QWebKit, I had to make the members functions look like this:

public slots:
    Q_INVOKABLE void print();

answered Sep 28 '15 at 18:59

emperor

71
1
3

1

thanks a ton man. qtwebengine also require Q_INVOKABLE. I never tried this. :( Now its working. – Gilson PJ Sep 29 '15 at 05:19

score 2 · Answer 2 · answered Dec 02 '15 at 20:24

I know I'm providing a comment late, but if the function in question is declared in the slots section, you don't have to use Q_INVOKABLE. Slightly less typing if there are several functions.

class MyClass : public QObject
{
    Q_OBJECT
public:
    MyClass(QObject *parent = 0);

slots:
    void print();
}

Qt: Cannot invoke shared object methods/properties from javascript

2 Answers2

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