如何使用PySide2在qml中设置值？

Question

我想从PySide2将值写入qml。这个值是动态变化的

对于这里的PyQt5示例：How to set values in qml using PyQt5?

main.py：

import sys

from PySide2.QtCore import QObject, Signal, Property, QUrl, QTimer, QDateTime
from PySide2.QtGui import QGuiApplication
from PySide2.QtQml import QQmlApplicationEngine

class Foo(QObject):
    textChanged = Signal()

    def __init__(self, parent=None):
        QObject.__init__(self, parent)
        self._text = ""

    @Property(str, notify=textChanged)
    def text(self):
        return self._text

    @text.setter
    def text(self, value):
        if self._text == value:
            return
        self._text = value
        self.textChanged.emit()


def update_value():
    obj.text = "values from PyQt5 :-D : {}".format(QDateTime.currentDateTime().toString())

if __name__ == "__main__":
    app = QGuiApplication(sys.argv)
    obj = Foo()
    timer = QTimer()
    timer.timeout.connect(update_value)
    timer.start(100)
    engine = QQmlApplicationEngine()
    engine.rootContext().setContextProperty("obj", obj)
    engine.load(QUrl("main.qml"))
    if not engine.rootObjects():
        sys.exit(-1)
    sys.exit(app.exec_())

main.qml：

import QtQuick 2.5
import QtQuick.Window 2.2

Window {
    id: parwin
    visible: true
    width: 640
    height: 480
    Text{
        anchors.fill: parent
        text:  obj.text
    }

}

我得到一个错误：

main.qml:11:9: Unable to assign [undefined] to QString
main.qml:11: TypeError: Cannot read property 'text' of null

告诉我我的错在哪里

Answer 1

PySide2似乎在setter中有一个bug，因此它没有正确注册属性，解决方案是创建一个具有不同名称的setter和getter，并分别使用Property（）来公开它：

# ...

class Foo(QObject):
    textChanged = Signal()

    def __init__(self, parent=None):
        QObject.__init__(self, parent)
        self._text = ""

    def get_text(self):
        return self._text

    def set_text(self, value):
        if self._text == value:
            return
        self._text = value
        self.textChanged.emit()

    text = Property(str, fget=get_text, fset=set_text, notify=textChanged)

# ...