Pass data from QML WorkerScript.sendMessage call through message signal - qml

Question

I want to create a QML WorkerScript object dynamically and read the output from its function in my JavaScript code. Here's what I'm trying in my QML file:
import QtQuick 2.0
Rectangle {
id: root
width: 200
height: 300
Component.onCompleted: {
var worker = Qt.createQmlObject('import QtQuick 2.0; WorkerScript { source: "dataloader.js"; }', root)
worker.sendMessage();
worker.message.connect(function (msg) { console.log(msg); });
}
}
And here's the source of the dataloader.js file:
WorkerScript.onMessage = function(msg) {
WorkerScript.sendMessage('test');
}
I would like the code to output "test" to the console but it outputs "QVariant(QQmlV4Handle)" instead. I see in some examples on the Qt site (http://doc.qt.io/qt-5/qml-workerscript.html and http://doc.qt.io/qt-5/qtquick-threading-example.html#workerscript) that there is a messageObject property but that doesn't seem to be accessible from the connect function when I try to access it with worker.messageObject. Can anyone point me in the right direction here?

Answer 1

I don't know why it works this way but I got the functionality I wanted by catching the message signal in the WorkerScript object and emitting the messageObject to a new signal that I added to the object. Here's a code sample (dataloader.js stays the same):
var worker = Qt.createQmlObject('import QtQuick 2.0;
WorkerScript {
signal loaded(var value);
source: "dataloader.js";
onMessage: { loaded(messageObject); }
}', root)
worker.loaded.connect(function (value) { console.log(value); });
worker.sendMessage();