sample elasticsearch query to sort parent based on child field

gistfile1.txt

{  
  "query":{  
    "has_child":{  
      "query":{  
        "function_score":{  
          "functions":[  
            {  
              "field_value_factor":{  
                "factor":1,
                "field":"count"
              }
            }
          ]
        }
      },
      "score_mode":"avg",
      "type":"my_child_doc_type"
    }
  }
}

Brilliant, Thanks. This worked like a charm for a POC I was working on that needed parents sorted based by children field... I also needed to:

1. query against the parent document.
2. return only the matched results that has children.
3. sorted by child.field.value.

This has fall short on 1. With any sort of query resulting to "nested: QueryParsingException...No query registered for [functions]]".

Any Idea on how to expand this to take say a "query_string"?

Cheers.

what if we needed to have results where filter needs to apply to both parent and child ?