How to access doc value on nested type in script query (filter context)

[f3l1xss (felix stanley)]

Hi Guys,

I have the below index:

cargroup

 "mappings": {
    "properties": {
      "id":     { "type": "integer" },
      "cars":   { "type": "nested",
                            "properties": {
                                    "brand": {
                                        "type": "keyword"
                                    },
                                    "value": {
                                        "type": "integer"
                                    }
                                }
                        },

How can I access cars properties using docs value in script query?

https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-script-query.html

After reading through the docs, I found out that script query is executed in filter context, which means that only docs and params are available.

https://www.elastic.co/guide/en/elasticsearch/painless/master/painless-filter-context.html

Is there any way I can alter the mapping so that nested type can be accessed through doc value?

This is the problem I am trying to solve:

How to perform filter based on aggregation of nested fields? (similar to nested sorting)

So far I haven't been able to found any other solution besides using script query. Any suggestions is welcome.

Thank you