CODEWITHSUNDEEP
pythonqmlpysidepyside2
Thane Brimhall
Thane Brimhall

Reputation: 9555

PySide Signal argument can't be retrieved from QML

I've noticed that QML can receive a signal emitted from Python by using the Connections object. Unfortunately, I can't figure out how to get that object to receive the arguments of that signal.

I've created a minimal test case that demonstrates what I want to do:

min.py

from PySide import QtCore, QtGui, QtDeclarative
import sys

# init Qt
app = QtGui.QApplication(sys.argv)

# set up the signal
class Signaller(QtCore.QObject):
    emitted = QtCore.Signal(str)

signaller = Signaller()

# Load the QML
qt_view = QtDeclarative.QDeclarativeView()
context = qt_view.rootContext()
context.setContextProperty('signaller', signaller)
qt_view.setResizeMode(QtDeclarative.QDeclarativeView.SizeRootObjectToView)
qt_view.setSource('min.qml')
qt_view.show()

# launch the signal
signaller.emitted.emit("Please display THIS text!")

# Run!
app.exec_()

And min.qml

import QtQuick 1.0

Rectangle {
    width:300; height:100

    Text {
        id: display
        text: "No signal yet detected!"

        Connections {
            target: signaller
            onEmitted: {
                display.text = "???" //how to get the argument?
            }
        }
    }
}

Upvotes: 6

Views: 3012

Answers (3)

Ruben Henares
Ruben Henares

Reputation: 11

Sorry i can't comment since i need to have higher reputation. In response to the "Cannot assign to non-existent property", it's caused by the order in which you initialize your application. Your root context object needs to be created before the engine.

Ok:

context = Context() engine = QQmlApplicationEngine() engine.rootContext().setContextProperty("context", context)

Not ok:

engine = QQmlApplicationEngine() context = Context() engine.rootContext().setContextProperty("context", context)

Upvotes: 0

Ben Hagen
Ben Hagen

Reputation: 645

As of Qt for Python versions 5.12.5, 5.13.1 it is working the same as in PyQt:

from PySide2.QtCore import Signal

sumResult = Signal(int, arguments=['sum'])
sumResult.emit(42)

QML:

onSumResult: console.log(sum)

Upvotes: 6

alexisdm
alexisdm

Reputation: 29896

As of Qt 4.8, PySide doesn't handle signal parameter names at all.

But you can create a QML signal with named parameters and connect your python signal to it using Javascript:

import QtQuick 1.0

Rectangle {
    width:300; height:100


    Text {
        id: display
        text: "No signal yet detected!"

        signal reemitted(string text)
        Component.onCompleted: signaller.emitted.connect(reemitted)

        onReemitted: {
          display.text = text;        
        }
    }
}

Upvotes: 5

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