Query from a field of Elasticsearch 7.3 using Java

Question

I have the following code working fine and returning the documents. I want to search based on only one field from the document and shall return the value of that field from all the documents.

        RestHighLevelClient client;

        QueryBuilder matchQueryBuilder = QueryBuilders.queryStringQuery("elon");
        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
        sourceBuilder.query(matchQueryBuilder);
        sourceBuilder.from(0);
        sourceBuilder.size(10);
        sourceBuilder.timeout(new TimeValue(60, TimeUnit.SECONDS));
        SearchRequest searchRequest = new SearchRequest(ELASTIC_SEARCH_INDEX);
        searchRequest.source(sourceBuilder);
        SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);

I need it to search only Name field and return the value of that field from all documents that returned in this search.

let say, I query Elon and it should response a List<String> "lily Elon musk", "parker Elon ",Elon musk 77" and ignore other fields.

Mapping

{
students: {
mappings: {
properties: {
students: {
properties: {
courseTitle: {
type: "text",
fields: {
keyword: {
type: "keyword",
ignore_above: 256
}
}
},
courseCode: {
type: "text",
fields: {
keyword: {
type: "keyword",
ignore_above: 256
}
}
},
name: {
type: "text",
fields: {
keyword: {
type: "keyword",
ignore_above: 256
}
}
},
courseGrade: {
type: "text",
fields: {
keyword: {
type: "keyword",
ignore_above: 256
}
}
}
}
}
}
}
}
}

Sample document

students: [
{
courseCode: " HM101",
courseTitle: "ICP",
courseGrade: "A"
},
{
courseCode: " CS101",
courseTitle: "electronice",
courseGrade: "B+"
},
{
name: "elon musk"
}]

@Gibbs the links that you have provided are 5 years old. Now a lot of methods deprecated. — Lily, Jun 22 '20 at 07:15
My bad. I updated links. I don't see any change related to the use case of this question. — Gibbs, Jun 22 '20 at 07:17
I meant the links in the answer, not in the comments. And moreover, you have a nested document [type](https://www.elastic.co/guide/en/elasticsearch/reference/current/nested.html) and `students` is nested type which has three objects. — Gibbs, Jun 22 '20 at 07:37

Gibbs · Answer 1 · 2020-06-22T07:17:51.047

0

I need it to search only Name field and return the value of that field from all documents that returned in this search.

Not a straight-forward one. You need to change query string as below to handle only name field.

JAVA way:

QueryBuilder matchQueryBuilder = 
               QueryBuilders.queryStringQuery("elon").defaultField("name");

String[] includeFields = new String[] {"name"};
String[] excludeFields = new String[] {"user"};
sourceBuilder.fetchSource(includeFields, excludeFields);

PLAIN:

  {
    "_source":
      ["name"],
    "query": {
        "query_string" : {
            "query" : "name:elon"

        }
    }

}

And you can do source controlling in code and Hope you are interested in query_string way only. If you are open to other ways, you can use this

Then to convert to List<String>, you need to iterate the response and add it to a List

SearchHits hits = searchResponse.getHits();
SearchHit[] searchHits = hits.getHits();
List<String> names = new ArrayList<String>();
for (SearchHit hit : searchHits) {
   Map<String, Object> sourceAsMap = hit.getSourceAsMap();
   names.add(sourceAsMap.get("name"));
}

edited Jun 22 '20 at 07:17

answered Jun 21 '20 at 18:15

Gibbs

21,904
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sir this is returning me nothing. 0 hits. – Lily Jun 21 '20 at 18:28
Can you add a sample document and mapping for `name` field? – Gibbs Jun 21 '20 at 18:29
If you have mapping like `keyword` or `not analyzed` then you may not expect the output as you desired. – Gibbs Jun 21 '20 at 18:32
I have not set the maping `keyword` etc . I just simply load data. – Lily Jun 21 '20 at 18:35
Can you run the below request and add it to the question - `http://host:9200/indexName/_mapping GET` – Gibbs Jun 21 '20 at 18:50
please check inn question – Lily Jun 21 '20 at 18:57
Please add a sample document also from the search query `http://hostNmae:9200/indexName/_search` – Gibbs Jun 21 '20 at 19:03
please check now. – Lily Jun 21 '20 at 19:10
What you have is a nested document - you need to use nested query - refer [https://stackoverflow.com/questions/31062264/elasticsearch-search-inside-the-array-of-objects] – Gibbs Jun 21 '20 at 19:31
And addition to the above comment, java way of doing - https://stackoverflow.com/questions/24710831/elasticsearch-java-client-querying-nested-objects – Gibbs Jun 21 '20 at 19:35

score 0 · Accepted Answer · answered Jun 22 '20 at 11:32

0

It works with

        String[] includeFields = new String[]{"students.name"};
        sourceBuilder.fetchSource(includeFields, null);

answered Jun 22 '20 at 11:32

Lily

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Query from a field of Elasticsearch 7.3 using Java

2 Answers2