如何使用 PySide2 在 qml 中设置值？

Question

从 PySide2 我想将值写入 qml。 该值动态变化。

对于此处的 PyQt5 示例： How to set values in qml using PyQt5?

主要.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_())

主.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
    }

}

我有错误：

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

告诉我我的错误在哪里？

Answer 1

看来PySide2 的setter 有一个bug，所以它没有正确注册Property，解决办法是创建一个不同名称的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)

# ...