my mail.qml is

import QtQuick 2.7
import QtQuick.Window 2.2
import QtQuick.Controls 1.2

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

Rectangle
{
    id: connectButton
    x: 130
    y: 10
    width: 70
    height: 30
    visible: true
    gradient: Gradient
    {
        GradientStop
        {
            position: 0
            color: "#ffffff"
        }

        GradientStop
        {
            position: 1
            color: "#000000"
        }
    }
    border.color: "#251f1f"

    Text
    {
        id: text1
        text: qsTr("Connect")
        verticalAlignment: Text.AlignVCenter
        horizontalAlignment: Text.AlignHCenter
        transformOrigin: Item.Center
        anchors.fill: parent
        font.pixelSize: 12
    }
    MouseArea
    {
        anchors.fill: parent

        onClicked:
        {
            console.log(qsTr("Connect Button Clicked"))// + textEdit.text + '"'))
           loader.source = "Graph.qml"

            //To-do

            //Connection with aurdino will come here
           /* viewButton.visible = true
            sensorButton.visible = true
            sensorOption.visible = true
            viewOption.visible = true*/


        }


    }

}


Rectangle {
    id: graphView
    x: 0
    y: 200
    width: 630
    height: 443
   gradient: Gradient {
        GradientStop {
            position: 0
            color: "#ffffff"
        }

        GradientStop {
            position: 1
            color: "#000000"
        }
    }


    Loader
    {
        id: loader
        anchors.bottomMargin: 0
        anchors.leftMargin: 0
        anchors.topMargin: 0
        anchors.rightMargin: 0
        anchors.fill: parent
    }
}



Column {
    id:sensorOption
    x:450
    y:80
    visible: true


    CheckBox {
        text: qsTr("Temperature")
        checked: true
        onClicked:
            if(checked == true)
            {
                 console.log(qsTr("Temperature Sensor selected")+test)

            }
        else
            {
                 console.log(qsTr("Temperature Sensor unselected"))
            }


    }
    CheckBox {
        text: qsTr("Torque")
        onClicked:
            if(checked == true)
            {
                 console.log(qsTr("Torque Sensor selected"))
            }
        else
            {
                 console.log(qsTr("Torque Sensor Unselected"))
            }
    }
    CheckBox
    {
        text: qsTr("Accelerometer")
        onClicked:
            if(checked == true)
            {
                 console.log(qsTr("Accelerometer Sensor selected"))
            }
        else
            {
                 console.log(qsTr("Accelerometer Sensor unselected"))
            }
   }
}

}

my graph.qml is

import QtQuick 2.0
import QtCharts 2.0

Item {
id: graph
anchors.fill: parent

ChartView {
    id:chartName
    title: "Sensor"
    anchors.fill: parent
    antialiasing: true

    LineSeries {
        id:temperature
        name: "Here name will come from mail.qml"
        XYPoint { x: 0; y: 0 }
        XYPoint { x: 1.1; y: 2.1 }
        XYPoint { x: 1.9; y: 3.3 }
        XYPoint { x: 2.1; y: 2.1 }
        XYPoint { x: 2.9; y: 4.9 }
        XYPoint { x: 3.4; y: 3.0 }
        XYPoint { x: 4.1; y: 3.3 }


    }

}

}