Q:

elastic search sort in aggs by column

I am trying to sort in elastic search in aggs, equivalent in mysql "ORDER BY Title ASC/DESC". Here is the index structure:
'body' => array(
  'mappings' => array(
    'test_type' => array(
      '_source' => array(
        'enabled' => true
    ),
    'properties' => array(
      'ProductId' => array(
        'type'      => 'integer',
         'index'     => 'not_analyzed'
      ),
      'Title' => array(
        'type'      => 'string',
        'index'     => 'not_analyzed'
      ),
      'Price' => array(
        'type'      => 'double',
         'index'     => 'not_analyzed'
                        )
    )
  )
)

I can order by Price as follows:
{
      "aggs": {
        "group_by_product": {
          "terms": {
            "field": "ProductId",
              "order": {
                "product_price" : "asc"
            }
          },
          "aggs": {
            "product_price": {
              "avg": {
                "field": "Price"
              }
            }
          }
        }
      }
    }

But it is not possible to order by Title (ORDER BY Title ASC/DESC). 
Is there any way to sort by Title?
Thank you very much in advance!
Regards

A:

Edit to reflect clarification in comments:
To sort an aggregation by string value use an intrinsic sort, however sorting on non numeric metric aggregations is not currently supported.
"aggs" : {
        "order_by_title" : {
            "terms" : {
              "field" : "title",
              "order": {
                "_term" : "asc" 
              }
            }
        }
    }

