title: Adding additional data points to a chart
body: <p>I am creating a simple bar chart (using <code>dimple.js</code>) showing participation in a chat room. The Y axis are the different participants and the X axis is the amount of messages they have sent to the room.</p>
  
  <p>The chart I am creating is very simple, and based on data from three columns (participantID, Participant_Name, Message_Count):</p>
  
  <pre><code>var svg = dimple.newSvg("#chrt_participants", 1200, 600);
  var chrt_participants = new dimple.chart(svg, data.result);
  chrt_participants.addCategoryAxis("y", "Participant_Name");
  chrt_participants.addMeasureAxis("x", "Message_Count");
  chrt_participants.addSeries(null, dimple.plot.bar);
  chrt_participants.draw();
  </code></pre>
  
  <p>I would like to associate the participantID into the chart, so that when someone for instance clicks on a bar, that ID is sent via an ajax call somewhere else. The challenge I am having is that I seem to only be able to access the values I explicitly send to the chart when creating it (via the <code>addCategoryAxis</code> and <code>addMeasureAxis</code> functions) and I am not able to assign any more values to a bar.</p>
  
  <p>So my question is, how do you assign more variables to an element of a chart, when those variables do not have any "visual purpose"?</p>