change basemap through token and item id

[rsharma]

I have been trying to access my private topological basemap in my app through btn click  and calling chooseBasemap(); fnc.

But it does not load my basemap. screen goes blank

this is my code below:

import QtQuick 2.13

import QtQuick.Controls 2.13

import QtQuick.Layouts 1.13

import QtPositioning 5.8

import QtLocation 5.9

import ArcGIS.AppFramework 1.0

import Esri.ArcGISRuntime 100.6

import "../assets/js/backend.js" as Backend

import "../controls" as Controls

Page {

    id: app

    property string itemID: "my map id"

    property string tItemId:"topo map id"

     property real scaleFactor: AppFramework.displayScaleFactor

    width: parent.width

    height: parent.height

    MapView {

        id:mapView

        property real initialMapRotation: 0

        anchors {

            left: parent.left

            right: parent.right

            top: parent.top

            bottom: parent.bottom

        }

        rotationByPinchingEnabled: true

        zoomByPinchingEnabled: true

    // add a basemap

    Map {

        id:map

        item: PortalItem {

            portal: portal

            itemId: itemID

        }

        }

    }//End Mapview

    //! [PortalUserInfo create portal]

    Portal {

        id: portal

        credential: Credential {

             token: Backend.getMapToken()

        }

        Component.onCompleted: {

            load();

            //fetchLicenseInfo();

        }

        onLoadStatusChanged: {

            if (loadStatus === Enums.LoadStatusFailedToLoad)

                retryLoad();

        }

    }

    Row{

        anchors.horizontalCenter: parent.horizontalCenter

        //anchors.margins: 70 * scaleFactor

        spacing:3

        leftPadding: 120

        topPadding: 15

        Controls.Kbutton {

            id: satellitebtn

            width: 100

            text: qsTr("SATELLITE")

            font.weight: Font.Bold

            Layout.alignment: Qt.AlignHCenter

            Layout.preferredWidth: 100

            borderColor: "#ff7919"

            font.pixelSize: 14

            Layout.preferredHeight: 40

            baseColor: "#FF7919"

            textColor: "#FFFFFF"

            onClicked: {

                    map.basemap = ArcGISRuntimeEnvironment.createObject("BasemapImagery");

            }

        }

        Controls.Kbutton {

            id: topobtn

            width: 88

            text: qsTr("TOPO")

            font.weight: Font.Bold

            Layout.alignment: Qt.AlignHCenter

            Layout.preferredWidth: 100

            borderColor: "#ffffff"

            font.pixelSize: 14

            Layout.preferredHeight: 40

            baseColor: "#ffffff"

            textColor: "#333333"

            onClicked: {

                chooseBasemap();

            }

        }

        Image {

            id: group1

            source: "../assets/images/Group1.png"

            height: 60

            width: 60

        }

    }

    Row{

   topPadding: 70

   leftPadding: 315

   anchors.horizontalCenter: parent.horizontalCenter

    Image {

        id: group2

        source: "../assets/images/Group22.png"

        height: 60

        width: 60

    }

    }

    function chooseBasemap() {

        var newMap = ArcGISRuntimeEnvironment.createObject("Map", {basemap: tItemId});

        mapView.map = newMap;

        mapView.visible = true;

    }

    footer: Controls.Kfooter {

         id:footer

     }

}

[rsharma]

i am also trying this way: but nothing shows on screen

function chooseBasemap() {

        console.log(ArcGISRuntimeEnvironment.createObject("Map", {portal: portal,itemId: itemID}));

        mapView.map = ArcGISRuntimeEnvironment.createObject("Map", {portal: portal,itemId: itemID});

    }

[rsharma · Accepted solution]

Finally i get the result But does this code replace my drawing polygons and 
,markers also which i m going to put in future in this code??
I just want to change basemap with my secured map here..
Can anyone tell me that i am going right way
 function chooseBasemap() {

               var credential = ArcGISRuntimeEnvironment.createObject("Credential", {  token: Backend.getMapToken() });

                var  securityPortal = ArcGISRuntimeEnvironment.createObject("Portal", { credential: credential });

               var item = ArcGISRuntimeEnvironment.createObject("PortalItem", { portal: securityPortal, itemId: tItemId });

               mapView.map= ArcGISRuntimeEnvironment.createObject("Map", { item: item });

           }

[ErwinSoekianto]

I think that is correct, you could probably re-use the Portal and Credential object that you already have. 

Tagging ArcGIS Runtime SDK for Qt‌ to see if there is a better way to solve this.