Ordering Drupal 6 events by date when you have empty / null dates

On one of my Drupal 6 sites I have a list of events, where the Event content type is provided by the Calendar module using Date for their date fields. These events need to be filtered by a date range and ordered with the most recent first. This would be easy if it weren’t for the fact that some events don’t have dates. Specifically, ‘from’ and ‘to’ dates.

I had to do two things:

1. To prevent events with an empty date being filtered out, I installed the Views Or module and use it to filter by date range OR events with empty date:

   Views Or: Begin alternatives =
   Date: Date (node) (Content: Date (field_date) - From date OR Content: Date (field_date) - To date) Exposed Popup Day
   Views Or: Next alternative =
   Content: Date - From date Content: Date (field_date) - From date AND Content: Date (field_date) - To date empty
   Views Or: End alternatives = 
   

2. To move the events with an empty date to the bottom of the list, I created a custom module to insert an ‘order by’ clause so that events with null dates would be listed last:

   /**
    * Implementation of hook_views_query_alter().
    * Sort null date fields last (rather than first) for the calendar view.
    */
   function mymodule_views_modifications_views_query_alter(&$view, &$query) {
     if ($view->name == 'calendar') {
       array_unshift($query->orderby, 'ISNULL(node_data_field_date_field_date_value) ASC');
     }
   }
   

   In this code, replace ‘mymodule’ with the name of your module, replace ‘calendar’ with the name of your view and replace ‘node_data_field_date_field_date_value’ with the name of your date field. You can determine these by printing out the $view and $query objects to inspect their contents.

References

• Views Or
• Infinite Null: Sorting NULL to Last

Last modified: 13/11/2013 Tags: drupal