[FEATURE] Support Search (Query) templates

[gquintillan]

Is your feature request related to a problem?

I would like to use the org.springframework.data.elasticsearch.core.query.SearchTemplateQuery but I get this error when I try to use it:

java.lang.IllegalArgumentException: unhandled Query implementation org.springframework.data.elasticsearch.core.query.SearchTemplateQuery
	at org.opensearch.data.client.orhlc.RequestFactory.getQuery(RequestFactory.java:1174) ~[spring-data-opensearch-1.2.0.jar:na]
	at org.opensearch.data.client.orhlc.RequestFactory.searchRequest(RequestFactory.java:752) ~[spring-data-opensearch-1.2.0.jar:na]
	at org.opensearch.data.client.orhlc.OpenSearchRestTemplate.search(OpenSearchRestTemplate.java:375) ~[spring-data-opensearch-1.2.0.jar:na]
	at org.springframework.data.elasticsearch.core.AbstractElasticsearchTemplate.search(AbstractElasticsearchTemplate.java:492) ~[spring-data-elasticsearch-5.1.2.jar:5.1.2]

What solution would you like?

Support org.springframework.data.elasticsearch.core.query.SearchTemplateQuery in

spring-data-opensearch/spring-data-opensearch/src/main/java/org/opensearch/data/client/orhlc/RequestFactory.java

Line 1174 in b671763

"unhandled Query implementation " + query.getClass().getName());

Do you have any additional context?

Search Templates are way to move the query logic to OpenSearch and make the code cleaner in the microservice side. Moreover this queries are more efficient since they are precompiled.

Example of use of query templates can be seen here: https://github.com/spring-projects/spring-data-elasticsearch/blob/main/src/main/antora/modules/ROOT/pages/elasticsearch/misc.adoc

public class PersonCustomRepositoryImpl implements PersonCustomRepository {

  private final ElasticsearchOperations operations;

  public PersonCustomRepositoryImpl(ElasticsearchOperations operations) {
    this.operations = operations;
  }

  @Override
  public SearchPage<Person> findByFirstNameWithSearchTemplate(String firstName, Pageable pageable) {

    var query = SearchTemplateQuery.builder()                               (1)
      .withId("person-firstname")                                           (2)
      .withParams(
        Map.of(                                                             (3)
          "firstName", firstName,
          "from", pageable.getOffset(),
          "size", pageable.getPageSize()
          )
      )
      .build();

    SearchHits<Person> searchHits = operations.search(query, Person.class); (4)

    return SearchHitSupport.searchPageFor(searchHits, pageable);
  }
}

[gquintillan]

I see that it might be supported in a different way using NativeSearchQueryBuilder.withSearchTemplate:

https://github.com/opensearch-project/spring-data-opensearch/blob/425d1795c8710193efd910b249c58f70e7b88349/spring-data-opensearch/src/main/java/org/opensearch/data/client/orhlc/NativeSearchQueryBuilder.java#L163C41-L163C55

Can someone provide an example? I don't know how to get an instance of OpenSearchClient which is needed in this constructor: https://github.com/opensearch-project/OpenSearch/blob/db90a415ff2fd428b4f7b3f800a51dc229287cb4/modules/lang-mustache/src/main/java/org/opensearch/script/mustache/SearchTemplateRequestBuilder.java#L48