I want to send dictionaries, containing data that I need to use to dynamically create qml objects, from a PySide2 class to a QML interface and since I need to do it in response to certain events, I need to use signals and slots.
Since I've just started to use QML and python I tried to create a simple project just to play around (as you can see from the code)
QML:
import QtQuick 2.10
import QtQuick.Controls 2.2
import QtQuick.Window 2.2
import QtQuick.Controls.Material 2.3
import QtQuick.Layouts 1.0
ApplicationWindow {
id: mainWindow
width:640
height: 480
title: qsTr("Simple ui")
visible: true
locale:locale
Rectangle {
id: appWindow
objectName: "splasso"
anchors.fill: parent
color: "yellow"
Material.accent: Material.DeepPurple
Material.primary: Material.Cyan
Component.onCompleted: function(){
TestVar.theSignal.connect(catchAnswer);
testList.append(stuff1);
testList.append(stuff2);
testList.append(stuff3);
testCombo.currentIndex = 0;
//Just a pointless test print
console.log(JSON.stringify(stuff1));
}
function catchAnswer(answer){
console.log(JSON.stringify(answer));
}
ComboBox{
id: testCombo
anchors.centerIn: parent
width: parent.width
onCurrentIndexChanged: function(){
TestVar.catchInt(currentIndex);
}
model: ListModel{
id: testList
}
}
}
}
Python 3:
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import sys
import os
from time import sleep
from PySide2.QtCore import Qt, QObject, Signal, Slot, Property, QThread
from PySide2.QtWidgets import QApplication
from PySide2.QtQml import QQmlApplicationEngine
class Test1(QObject):
theSignal = Signal(dict)
def __init__(self):
QObject.__init__(self)
@Slot(int)
def catchInt(self,caught):
print("Caught: {0}".format(caught))
testDict = {"myAnswer":caught}
self.theSignal.emit(testDict)
if __name__ == "__main__":
os.environ["QT_QUICK_CONTROLS_STYLE"] = "Material"
app = QApplication(sys.argv)
engine = QQmlApplicationEngine()
stuff1 = {"text":"Trying"}
stuff2 = {"text":"To send"}
stuff3 = {"text":"Dict"}
ctx = engine.rootContext()
ctxVar = Test1()
ctx.setContextProperty("stuff1", stuff1)
ctx.setContextProperty("stuff2", stuff2)
ctx.setContextProperty("stuff3", stuff3)
ctx.setContextProperty("TestVar",ctxVar)
engine.load('main.qml')
if not engine.rootObjects():
sys.exit(-1)
sys.exit(app.exec_())
The outuput I expected (launching the script with "python3 Test_dict_1.py") was:
Caught: 1
qml: {"myAnswer": 1}
Caught: 2
qml: {"myAnswer": 2}
Caught: 1
qml: {"myAnswer": 1}
...etc...
What I got instead was:
Caught: 1
qml: undefined.
Caught: 2
qml: undefined.
Caught: 1
qml: undefined.
...etc...
Can you tell me what am I doing wrong? Are there errors in the code or this thing cannot be done?
The signature you have to use in the signal is QVariant
:
class Test1(QObject):
theSignal = Signal('QVariant')
@Slot(int)
def catchInt(self,caught):
print("Caught: {0}".format(caught))
testDict = {"myAnswer":caught}
self.theSignal.emit(testDict)