How to use ungrouped date fields as data for Charts Views? I have a content type with the following date fields:


Start Date
Deadline Date
End Date


Deadline date is programmatically calculated, where as Start and End are based on user input. 

There is a page with a table view for open nodes, ones without an End Date. In it, I would like to have a graphical representation of nodes alongside a graphical representation of time left from now until End Date.

I made a chart block view with serials as labels and dates as data, but the only result I got was a flat line with 0. Then tried every format combination listed under the date field without any luck. Although that, post date  as a field seems to return correct results(?).

For a specific node Devel listed the following:

created (String, 10 characters ) 1451882207

field_end_date (Array, 1 element)
    und (Array, 1 element)
    $...-&gt;field_end_date['und']
        0 (Array, 4 elements)
            value (String, 19 characters ) 2016-10-27 00:00:00
            timezone (String, 11 characters ) Asia/Riyadh
            timezone_db (String, 11 characters ) Asia/Riyadh
            date_type (String, 8 characters ) datetime


Creating timestamp fields gave the same flat line. So, I am unsure about what the exact issue is. Help would be appreciated on how to reach the desired outcome or about how to debug this if it is not a feature.

I'm using Charts version 7.x-2.x-dev.
I found a partial workaround for this by using hook_views_pre_render.

function hook_views_pre_render(&amp;$view) {
   if($view-&gt;name == 'stuff'){
      $results = &amp;$view-&gt;result;
      foreach ($results as $key =&gt; $result) {
      $now = time();
      $end = strtotime($result-&gt;field_field__end_date_[0]['raw']['value']);
      $daysuntil = date("j", $end-$now);
      $result-&gt;field_field_end_date[0]['rendered']['#markup'] = $daysuntil;
     }
   }
}


The previous function is  for a chart that displays node serials as x-axis labels and number of days for yaxis, which is calculated as the difference  between now and a end date.