Faceting hibernate search results by Instant range fails

Question

I have an entity with indexed creation timestamp of java.time.Instant type and I'd like to facet search results by creation timestamp range.
The entity looks the following way:

@Entity
@Indexed
public class Document {

    @Id
    @DocumentId
    private Long id;

    @Field
    private String name;

    @Field(analyze = Analyze.NO)
    @Facet
    private Instant creationTimestamp;
}

When I start my application I get the following error:

org.hibernate.search.exception.SearchException: HSEARCH000264: @Facet is not supported for type 'java.time.Instant'. See org.hibernate.search.bugs.Document#creationTimestamp

I haven't found anything related to faceting by Instant value in hibernate documentation .

Is it possible to facet hibernate search results by creation timestamp range?

I've created a failing test case here: github repo link

Answer 1

I'm afraid Java 8 date/time types are not yet supported in the Hibernate Search faceting subsystem. I created an ticket to address this, but I can't say when we will (there are internal complications): https://hibernate.atlassian.net/browse/HSEARCH-2954

UPDATE : Facets on date/time types are supported in Hibernate Search 6 with aggregations, which replace Hibernate Search 5 facets. Getting started with Hibernate Search 6 , Aggregations in Hibernate Search 6 .

In the meantime, you can work around this lack of support by using a @Transient long field representing the timestamp:

@Entity
@Indexed
public class Document {

    @Id
    @DocumentId
    private Long id;

    @Field
    private String name;

    private Instant creationTimestamp;

    @Field(analyze = Analyze.NO)
    @Facet
    @javax.persistence.Transient
    public Long getCreationForFaceting() {
        return creationTimestamp == null ? null : creationTimestamp.toEpochMilli();
    }
}

And then querying using long timestamps too.

Not an ideal solution by a long shot, but it's the only one I can think of.