Reuse/cache script fields to use other parts of the query

[anam (Anam Hossain)]

I am working on a project where we need to show distance the listings are from a user location. To show the distance, when lat/lon is given in the input, we calculate distance using a script field called "distance"

"script_fields" : {
        "distance" : {
            "script" : {
                "lang": "painless",
                "source": "Math.round((doc['location'].planeDistanceWithDefault(params.lat, params.lon, 0) * 0.001) * 100.0) / 100.0",
                "params" : {
                    "lat"  : -33.8152,
                    "lon" : 151.0012
                }
            }
        }
    }

However, for relevancy search, we want to rank the nearest listing higher and we are calculating the distance again inside the function score query. This is inefficient. I have searched the internet to find a solution but no luck.

Is there any way to reuse a script field in the other parts of the query or filter or sorting?

Full Query:

GET /listings/_doc/_search
{
    "_source" : true,
    "query": {
        "function_score": {
            "score_mode": "sum",
            "query": { "match": {
          "source_id": 1
        } },
            "functions": [
              {
                "script_score": {
                  "script": {
                    "params": {
                      "dealer": {"a": 5, "b": 6},
                      "photo": {"a": 4, "b": 5},
                      "location": {"lat": -33.8152, "lon": 151.0012}
                    },
                    "source": "(doc['location'].planeDistanceWithDefault(params.location.lat, params.location.lon, 1000) * 0.001 < 25 ? 200000 : 0) + (doc['is_dealer'].value == 1 ? Math.pow(params.dealer.a, params.dealer.b) : 0) + (doc['hasPhoto'].value == 1 ? Math.pow(params.photo.a, params.photo.b) : 0)"
                  }
                }
              }
            ]
        }
    },
    "script_fields" : {
        "distance" : {
            "script" : {
                "lang": "painless",
                "source": "Math.round((doc['location'].planeDistanceWithDefault(params.lat, params.lon, 0) * 0.001) * 100.0) / 100.0",
                "params" : {
                    "lat"  : -33.8152,
                    "lon" : 151.0012
                }
            }
        }
    }
}