Changing the text of a button

Hi,

Using this code in a QML program I want to change the text of a button when clicked:

main.qml:

Code:

---

import QtQuick 2.9
import QtQuick.Window 2.2
import QtQuick.Controls 1.4
import QtQuick.Controls.Styles 1.4
 
Window {
    visible: true
    width: 720; height: 720
    color: "gray"
 
    Rectangle {
        id: root
        x: 10; y: 10
        width: 300; height: 300
        color: "lightblue"
 
        function change() {
            st_text.text = "Clicked"
        }
 
        Button {
            id: b1
            x: 100; y: 100
            style: ButtonStyle {
                background: Rectangle {
                    implicitHeight: 50
                    implicitWidth: 100
                    color: "lightGrey"
                    border.width: 4
                    border.color: "lightBlue"
                    radius: 15
                    Text {
                        id: st_text
                        anchors.centerIn: parent
                        text: "Start"
                        font.bold: true
                        font.pixelSize: 15
                        color: "green"
                    }
                }
            }
            onClicked: root.change()
        }
    }
}

---

But when I click the button I get this error:
qrc:/main.qml:18: ReferenceError: st_text is not defined

Why and how to solve that please?

Maybe try moving the definition of your function change() to -after- the declaration of Button. I don't know much QML, but it may require that ids must be defined before they can be used. st_text isn't defined until after Button is declared.

If that isn't it, then maybe st_text is ambiguous, and you need to qualify it as "b1.st_text".