（QT 5.14）我想做一个日期选择按钮,单击按钮时调用不成功，请求帮助，如何解决？

（QT 5.14）我想做一个日期选择按钮，在main.qml中调用日历控件Demdiag.qml，main.qml使用QtQuick.Controls 2.5，Demdiag.qml使用QtQuick.Controls 1.4(因为 日历控件
Calendar Controls 1.0中才能用，所心单独做了日历文件Demdiag.qml)， 用单击调用，代码为：
select.onClicked: {
//datexz.text = Demdiag.visible = true
//Demdiag.dateDialog.visible = true
//Demdiag.visible = true
}
在单击时显示：TypeError: Value is undefined and could not be converted to an object，不能显示日历面板。(//datexz.text = Demdiag.visible = true
//Demdiag.dateDialog.visible = true
//Demdiag.visible = true上述三种调用方法都不成功）
)

//main.qml
import QtQuick 2.12
import QtQuick.Window 2.2
import QtQuick.Controls 2.5
import QtQuick.Controls.Styles 1.4

Window {
visible: true
width: 640
height: 480
title: qsTr("Hello World")

MainForm {
    id: main        
    select.onClicked: {
        //datexz.text = Demdiag.visible = true
        //Demdiag.dateDialog.visible = true
        //Demdiag.visible = true
     
    }
}

}
//Demdiag.qml
import QtQuick 2.6
import QtQuick.Controls 1.4
import QtQuick.Dialogs 1.2
import QtQuick.Controls.Styles 1.4

Item {
property alias dateDialog: dateDialog
Rectangle {
//(a)
id: dateDialog
//title: "选择日期"
width: 275
height: 300
border {
width: 3
color: "blue"
}

    //standardButtons: StandardButton.Save | StandardButton.Cancel
    //        onAccepted: datexz.text = calendar.selectedDate.toLocaleDateString(
    //                        )
    Calendar {
        //日历控件
        id: calendar
        //双击日历就等同于单击“Save”按钮
        //onDoubleClicked: dateDialog.click(StandardButton.Save)
    }
}

}
//MainForm.ui.qml
import QtQuick 2.0
import QtQuick.Controls 2.2
import QtQuick.Layouts 1.3
Page {
property alias select: select
property alias datexz: datexz
RowLayout {
TextField {
id: datexz
implicitWidth: 120
text: "2022年1月1日"
}
Button {
id: select
text: "选择日期"
}
}
}

Qt dateEdit 选择日期控件
https://www.csdn.net/tags/MtTaAgzsNTkyOTg3LWJsb2cO0O0O.html