Hibernate Search is a library that integrates Hibernate ORM with Apache Lucene or Elasticsearch by automatically indexing entities, enabling advanced search functionality: full-text, geospatial, aggregations and more. For more information, see Hibernate Search on hibernate.org.

During my talk at VoxxedVienna on using Hibernate Search with Elasticsearch earlier this week, there was an interesting question which I couldn’t answer right away:

"When running a full-text query with a projection of fields, is it possible to return the result as a list of POJOs rather than as a list of arrays of Object?"

The answer is: Yes, it is possible, result transformers are the right tool for this.

Let’s assume you want to convert the result of a projection query against the VideoGame entity shown in the talk into the following DTO (data transfer object):

public static class VideoGameDto {

    private String title;
    private String publisherName;
    private Date release;

    public VideoGameDto(String title, String publisherName, Date release) {
        this.title = title;
        this.publisherName = publisherName;
        this.release = release;

    // getters...

This is how you could do it via a result transformer:

FullTextEntityManager ftem = ...;

QueryBuilder qb = ftem.getSearchFactory()
    .forEntity( VideoGame.class )

FullTextQuery query = ftem.createFullTextQuery(
        .onField( "tags" )
        .matching( "round-based" )
    .setProjection( "title", "publisher.name", "release" )
    .setResultTransformer( new BasicTransformerAdapter() {
        public VideoGameDto transformTuple(Object[] tuple, String[] aliases) {
            return new VideoGameDto( (String) tuple[0], (String) tuple[1], (Date) tuple[2] );
    } );

List<VideoGameDto> results = query.getResultList();

I’ve pushed this example to the demo repo on GitHub.

There are also some ready-made implementations of the ResultTransformer interface which you might find helpful. So be sure to check out its type hierarchy. For this example I found it easiest to extend BasicTransformerAdapter and implement the transformTuple() method by hand.

To the person asking the question: Thanks, and I hope this answer is helpful to you!

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