Calculating a duration given a start and end time

This example uses KarenS' Date module to create a date field, "field_date", with both a start time and an end time that records hours and minutes. We then create a new computed field to calculate the duration as a decimal number of hours (where 1.5 is 1 hour and 30 minutes).

Computed field settings

• Computed Code:
  

  $field_info = array_pop(field_get_items($entity_type, $entity, 'field_date'));
  
  $start = $field_info['value'];
  $end = $field_info['value2'];
  $timezone = $field_info['timezone'];
  
  $date_start = new DateTime($start, $timezone);
  $date_end = new DateTime($end, $timezone);
  
  $interval = $date_start->diff($date_end);
  
  $entity_field[0]['value'] = $interval->format('%h');
  

• Display Code:
  

  $display_output = $entity_field_item['value'] . " hours";
  

• Check "Store using the database settings below".
• Data Type: float
• Data Length: 3,2

Now if you set the start time field to 0900h and the end time to 1130h, your computed field will store the value "2.5" and display "2.5 hours".