Elastic Search : Mapping date format and sort by date

While working on the job board for Socketloop.com recently, I need to sort the Elastic Search result based on the date when the entry is created.

Before the sorting part can happen, first the mappings need to be configured with the type "date" with a proper formatting.

 "postDate": {"type": "date", "format" : "yyyy-MM-dd HH:mm:ss"}

and below is a snippet from the Elastic Search mapping.

 "mappings" : {
 "people": {
 "properties": {
 "username": {"type": "string"},
 "postDate": {"type": "date", "format" : "yyyy-MM-dd HH:mm:ss"}
 }
 }

and add the 'sort' section in my Elastic Search query

 $searchquery = '{
 "size" : 9999,
 "sort" : [
 { "postDate" : {"order" : "desc"}}
 ]
 }';

and the result be seen at https://profession.socketloop.com/people (still pretty new and not many records to sort for the moment - March 2015)

Reference :

http://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-date-format.html