Unsolved UI doesn't update when Python QAbstractListModel changes from a Thread
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I posted the following as a QT bug, but after further work I am beginning to think that I am missing something:
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When running the attached code the UI doesn't update until i resize the window, and I get the following error:QObject::connect: Cannot queue arguments of type 'QQmlChangeSet'
(Make sure 'QQmlChangeSet' is registered using qRegisterMetaType().)I am not sure if this is PySide 2 bug, an underlying QT issue, or I am supposed to do something in my code to make this work.
Also I reported the issue as 5.12.2 of QT but it may be in 5.11.2, as I have both installed.
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So I am now wondering if the issue is that i somehow have to update the QAbstractListModel from the UI thread and not from my own thread -- the equivalent of Platform.runLater in JavaFX. So how do I do that?Also how do I actually change the ListView's model from Python? I don't want to change the contents of the ListView's model, I want to change it to a completely different model ....
thanks
G-- here is the code -- can't upload it for some reason
-- python code import sys from PySide2.QtCore import QAbstractListModel, Qt, QByteArray, SIGNAL, QModelIndex from PySide2.QtGui import QGuiApplication from PySide2.QtWidgets import QListView from PySide2.QtQuick import QQuickView from PySide2.QtQml import QQmlComponent from PySide2.QtQml import qmlRegisterType class PersonModel (QAbstractListModel): MyRole = Qt.UserRole + 1 def __init__(self, parent = None): QAbstractListModel.__init__(self, parent) self._data = [] def roleNames(self): roles = { PersonModel.MyRole : QByteArray(b'modelData'), Qt.DisplayRole : QByteArray(b'display') } return roles def rowCount(self, parent=QModelIndex()): return len(self._data) def data(self, index, role): d = self._data[index.row()] if role == Qt.DisplayRole: return d['name'] elif role == Qt.DecorationRole: return Qt.black elif role == PersonModel.MyRole: return d['myrole'] return None def appendRow(self, n, t): self.beginInsertRows(QModelIndex(), self.rowCount(), self.rowCount()) self._data.append({'name':n, 'myrole':t}) self.endInsertRows() def populate(self): self.appendRow('Asterix', 'role1') self.appendRow('Obelix', 'role2') from threading import Thread from time import sleep def function01(arg, myModel, name): for i in range(arg): print(name,'i---->',i,'\n') print (name,"arg---->",arg,'\n') sleep(10) myModel.appendRow(name + str(i), 'role1') # index = len(myModel._data) # myModel.foo(index) if __name__ == '__main__': app = QGuiApplication(sys.argv) # qmlRegisterType(PersonModel, 'Charts', 1, 0, 'PersonModel'); # qmlRegisterType(PersonModel, 'Charts', 1, 0, 'PersonModel'); view = QQuickView() view.setResizeMode(QQuickView.SizeRootObjectToView) myModel = PersonModel() myModel.populate() print(myModel._data) view.rootContext().setContextProperty("myModel", myModel) view.setSource('view.qml') thread1 = Thread(target=function01, args=(5, myModel, 'thread1',)) thread1.start() # thread1.join() # thread2.join() view.show() app.exec_() # Deleting the view before it goes out of scope is required to make sure all child QML instances # are destroyed in the correct order. del view
-- view.qml import QtQuick 2.0 ListView { id : xxx width: 100 height: 100 anchors.fill: parent model: myModel delegate: Component { Rectangle { height: 25 width: 100 Text { function displayText() { var result = "" if (typeof display !== "undefined") result = display + ": " result += modelData return result } text: displayText() } } } }