Is it posible to project _source ? many fields?

Siren Federate (Elasticsearch Plugin)
1

for example I have 2 indicies

  1. countries
  2. states

PUT /countries/_mapping

{
  "dynamic" : "strict",
  "properties" : {
    "id" : {
      "type" : "keyword"
    },
    "geo" : {
      "type" : "geo_point"
    },
    "name" : {
      "type" : "text"
    },
    "numberISO" : {
      "type" : "integer"
    }
  }
}

PUT /states/_mapping

{
  "dynamic" : "strict",
  "properties" : {
    "countryID" : {
      "type" : "keyword"
    },
    "id" : {
      "type" : "keyword"
    },
    "geo" : {
      "type" : "geo_point"
    },
    "name" : {
      "type" : "text"
    },
    "numberISO" : {
      "type" : "integer"
    }
  }
}

JOIN on [“id”, “countryID”]

as a result I want to get a set of included documents, like this:

"hits" : [
    {
      "_index" : "countries",
      "_type" : "_doc",
      "_id" : "1",
      "_score" : 1.0,
      "_source" : {
        id: '1',
        ...
      },
      "fields" : {
        "states" : [
          {
            "countryID": '1',
            "id": '2',
            "numberISO": 123
          },
          {
            "countryID": '1',
            "id": '3',
            "numberISO": 345
          },
          ...
        ]
      }
    }
  ]
2

At the moment you can only project fields, see Query domain-specific language (DSL) :: SIREN DOCS
However, this is not enough for you because the values of each document would get mixed.

3

yes it’s definitely not what I’m looking for, but could it be possible to do it with some scripts tricks ?

let me show you the simplest one

"query" : {
        "join" : {
          "indices" : ["states"],
          "on" : ["id", "countryID"],
          "request": {
            "project" : [
              {
                "script_field" : {
                  "name" : "_states",
                  "type" : "keyword",
                  "script" : {
                    "source" : "return 'id@@' +  doc.id + '##countryID@@' +  doc.countryID + '##geo@@' + doc.geo",
                    "lang" : "painless"
                  }
                }
              }
            ]
            }
          }
        }
      },
      "script_fields": {
        "states": {
          "script": {
            "source": "HashSet s = new HashSet(); for (String x: doc._states) { HashMap hm = new HashMap(); for (String y: /##/.split(x)) { String[] v = /@@/.split(y); hm.put(v[0], v[1]); } s.add(hm); } return s;",
            "lang": "painless"
          }
        }
      }

The main problem that here we’re losing fields types, all fields values are string no matter is it number or something else

4

were you able to solve it with the script ? I am in a similar situation. Trying to get few fields from join and I am getting it as a cartesian product. Not sure how to avoid it