title: Allow display of multiple data attributes in tooltip of Chart.js
body: <p>I am currently working with <a href="http://www.chartjs.org/" rel="nofollow">Chart.js</a> (<a href="https://github.com/reactjs/react-chartjs" rel="nofollow">react version</a>), and I am unable to figure out this problem. I am using a bar chart to display the data. By default, the tooltip only shows the current height of the corresponding bar.</p>
  
  <p><em>My requirement</em>:</p>
  
  <p>I have data that is available in json format with the following attributes</p>
  
  <pre><code>{
      value1: "",
      value2: "",
      value3: ""
  }
  </code></pre>
  
  <p>The height of the bar in the <a href="http://www.chartjs.org/docs/#bar-chart" rel="nofollow">bar chart</a> should be decided by <em>value1</em> attribute. When we hover on a particular bar, the tooltip should show all information of all three attributes. </p>
  
  <p>I am able to get the graph for only value1. I have looked into the <a href="http://www.chartjs.org/docs/#chart-configuration-tooltip-configuration" rel="nofollow">tooltip configuration</a> available in the docs, but could not achieve the requirement.</p>
  
  <p>(I am using react-chartjs)
  How do I do this? Thanks in advance</p>