Elastic Search: How to extract All “FieldNames” that Match the Query Phrase/String

Question

I want to extract the field names where the search text appears in the elastic search (stored) indexed documents.

Is this type of querying possible in elastic search, I am using Nest Client in C#

Please refer to the example below:

Example: employee document { "first_name" : "emp first", "last_name" : "emp last" }

Input search text: "first" Expected out : ["first_name"]

Input search text : "emp" Expected output : ["first_name", "last_name"]

Thanks, AT

Answer 1

There is a feature in elasticsearch "Named Queries" , you can named each query and elasticsearch will return the matched queries names

For your case you can use this query

GET index/doc_type/_search
{
  "_source": [
    "first_name",
    "last_name"
  ],
  "query": {
    "bool": {
      "should": [
        {
          "match": {
            "first_name": {
              "query": "emp",
              "_name": "first_name"
            }
          }
        },
        {
          "match": {
            "last_name": {
              "query": "emp",
              "_name": "last_name"
            }
          }
        }
      ]
    }
  }
}

Elasticsearch will return result like this one

{
  "took": 90,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 1,
    "max_score": 16.399673,
    "hits": [
      {
        "_index": "index",
        "_type": "doc_type",
        "_id": "1",
        "_score": 16.399673,
        "_routing": "1",
        "_source": {
          "first_name": "emp first",
          "last_name": "emp last"
        },
        "matched_queries": [
          "first_name",
          "last_name"
        ]
      }
    ]
  }
}

You can also do the same thing with highlighting

GET index/doc_type/_search
{
  "_source": [
    "first_name",
    "last_name"
  ],
  "query": {
    "bool": {
      "should": [
        {
          "match": {
            "first_name": "emp"
          }
        },
        {
          "match": {
            "last_name": "emp"
          }
        }
      ]
    }
  },
  "highlight": {
    "fields": {
      "first_name": {},
      "last_name" : {}
    }
  }
}

Sample Response :

{
  "took": 90,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 1,
    "max_score": 16.399673,
    "hits": [
      {
        "_index": "index",
        "_type": "doc_type",
        "_id": "1",
        "_score": 16.399673,
        "_routing": "1",
        "_source": {
          "first_name": "emp first",
          "last_name": "emp last"
        },
        "highlight": [
          "first_name" : ["<em>emp</em> first"],
          "last_name" : ["<em>emp</em> last"]
        ]
      }
    ]
  }
}