Angular 1.5 Two-Way Binding

HTML

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.0/angular.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.1.6/Chart.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular-chart.js/1.0.0-alpha8/angular-chart.js"></script>
<div ng-app="myApp" ng-controller="mainController">
    <canvas id="bar" class="chart chart-bar"
  chart-data="data" chart-labels="labels" chart-series="series" chart-colors="colors" chart-options="options"></canvas>
</div>

JavaScript

var app = angular.module('myApp', ["chart.js"]);

app.controller('mainController', function($scope) {
        $scope.labels = ['sun', 'moon', 'mars', 'venus'];
        $scope.series = ['sun', 'moon', 'mars', 'venus'];

        $scope.data = [
          [20, 0, 0, 0],
          [0, 10, 0, 0],
          [0, 0, 40, 0],
          [0, 0, 0, 30]
        ];
        
        $scope.colors = [
        	{
          	backgroundColor: '#645',
            borderWidth: 0
          },
          {
          	backgroundColor: '#E64',
            borderWidth: 0
          },
          {
          	backgroundColor: '#97F',
            borderWidth: 0
          },
          {
          	backgroundColor: '#24D',
            borderWidth: 0
          }
        ];
        
        $scope.options = {
              tooltips: {
              	callbacks: {
                  label: function(tooltipItem, data) {
                  	if(tooltipItem.yLabel) {
                    	return ' ' + tooltipItem.yLabel
                    }
                  }
                }
              },
              scales: {
                 yAxes: [{
                      ticks: {
                           beginAtZero: true,
                      }
                 }],
                 xAxes: [{
                 		stacked:true,
                 }]
              }
        };
});