How to write query elastic search?

Question

I have a index review like this

{
    "_index": "zody_review",
    "_type": "review",
    "_id": "5b3c6c9e68cf860e1af5f7fd",
    "_score": null,
    "_source": {
      "user": "571899623dc63af34d67a662",
      "merchant": "56f8f80119a4c1ae791cf7bf",
      "point": 3,
      "score": 2,
      "createdAt": "2018-07-04T13:43:42.331+07:00",
      "location": {
        "lat": 16.07054040054832,
        "lon": 108.22062939405441
      },
      "feedback": "Phuc vu khong tot lam "
    }
},

How can I query to get list review nearby, but limit get 5 reviews for each group by field merchant? I've been stuck here too long! Thank you!

Answer 1

You need to only return reviews that are near (say 100m) a given location and then you need to aggregate by marchant terms and add a top_hits sub-aggregation. It goes like this:

{
  "size": 0,
  "query": {
    "geo_distance": {
      "distance": "100m",
      "location": {
        "lat": 16.07055,
        "lon": 108.2207
      }
    }
  },
  "aggs": {
    "by_merchant": {
      "terms": {
        "field": "merchant"
      },
      "aggs": {
        "top_5": {
          "top_hits": {
            "_source": [
              "feedback"
            ],
            "size": 5
          }
        }
      }
    }
  }
}

Simply replace the location by the one you want to search around and probably the distance if you need a larger or smaller distance.