i have a python class named Manager and it's been registered like this :

backend = Manager()
engine = QQmlApplicationEngine()
engine.rootContext().setContextProperty("backend", backend)

also in this class (Manager) i have a property named paramDs :

from PySide2.QtCore import QObject, Signal, Property, Slot

class Manager(QObject):
    processResult = Signal(bool)

    def __init__(self):
        QObject.__init__(self)
        self.ds = "loading .."

    @Slot()
    def start_processing(self):
        self.set_ds("500")

    def read_ds(self):
        return self.ds

    def set_ds(self, val):
        self.ds = val

    paramDs = Property(str, read_ds, set_ds)

also in my qml i have a Table View :

    import QtQuick 2.14
    import Qt.labs.qmlmodels 1.0
    TableView {
        id:tb
        anchors.fill: parent
        columnSpacing: 1
        rowSpacing: 1
        clip: true
    
        model: TableModel {
            TableModelColumn { display: "param_name" }
            TableModelColumn { display: "value" }
    
            rows: [
                {
                    "param_name": "Param",
                    "value": "Value"
                },
                {
                    "param_name": "number of classes",
                    "value": backend.paramDs
                }
            ]
        }
    
        delegate: Rectangle {
            implicitWidth: displayer.width   50 <100 ? 100 :displayer.width 50
            implicitHeight: 50
            color : "#aa009688"
    
            Text {
                id:displayer
                text: display
                color : "white"
                anchors.centerIn: parent
            }
        }
    }

now some where in qml i call start_processing() slot . now paramDs should change in table view from "loading .." to "500" but it remained old "loading .." value.

why property does not update it self in qml?

CodePudding user response：

you should set Row value after setting property, like this:

        tbModel.setRow(1,
            {
                param_name: "number of classes",
                value: backend.paramDs
            }
        )

tbModel is id of your Table View's Model

CodePudding user response：

If you are creating a binding then the property must be notifiable, that is, have an associated signal and emit it when it changes:

class Manager(QObject):
    processResult = Signal(bool)
    df_changed = Signal()

    def __init__(self):
        QObject.__init__(self)
        self.ds = "loading .."

    @Slot()
    def start_processing(self):
        self.set_ds("500")

    def read_ds(self):
        return self.ds

    def set_ds(self, val):
        self.ds = val
        self.df_changed.emit()

    paramDs = Property(str, read_ds, set_ds, notify=df_changed)