Can't hibernate search sort in @OneToMany association?

Question

I try to sort a list of Items for a customer by ordered Date. The Date is only avalable through Item.orderPositions.order.orderDate . But @IndexedEmbedded doesn't work. There's no Exeption or Error but the result is only sorted by HS-logic.

    @Entity
    @Indexed
    public class Item{
        @Id
        private long id;

        @Field(index = Index.YES, store = Store.YES, analyse = Analyse.YES, analyser = @Analyzer(definition = Constant.ANALYSER))
        private String description;

        @OneToMany(mappedBy = "item")
        @IndexedEmbedded
        private List<OrderPosition> orderPositions;

        @ManyToOne
        @IndexedEmbedded
        private Company company;           
    //getter&setter
    }

    @Entity
    public class OrderPosition{
        @Id
        private long id;

        @ManyToOne
        private Item item;

        @ManyToOne
        @IndexedEmbedded
        private Order order;
    //getter&setter
    }

    @Entity
    public class Order{
        @Id
        private long id;

        @ManyToOne
        private Customer customer;

        @Field(index = Index.NO, store = Store.NO, analyze = Analyze.NO)
        @SortableField
        private String orderDate;
    //getter&setter
    }

    @Entity
    public class Company{
        @Id
        private long id;

        @Field(index = Index.NO, store = Store.NO, analyze = Analyze.NO)
        @SortableField
        private String name;
    //getter&setter
    }

If I sort the List by Item.company.name it works fine.

    queryService.buildFullTextQuery("searchText", Item.class, "description", "company.name").getResultList();

If I sort the List by Item.orderPosition.order.orderDate it's sorted by default(HS-logic)

    queryService.buildFullTextQuery("searchText", Item.class, "description", "orderPositions.order.orderDate").getResultList();

I build the FullTextQuery this way:

    public FullTextQuery buildFullTextQuery(@NonNull String searchText, @NonNull Class<?> clazz, @NonNull String... fields) throws Exception {
        FullTextEntityManager fullTextEntityManager = Search.getFullTextEntityManager(getEntityManager());
        QueryBuilder qb = fullTextEntityManager.getSearchFactory().buildQueryBuilder().forEntity(clazz).get();
        Query query = qb.keyword().onField(fields[0]).matching(searchText).createQuery();
        SortField sortField = new SortField(fields[1], SortField.Type.STRING, false);
        Sort sort = new Sort(sortField);
        return fullTextEntityManager.createFullTextQuery(query, clazz).setSort(sort);
    }

I think HS can't find the association for @OneToMany. Is there a way to solve this prob?

Thank you in advance

Answer 1

I can't tell you what's going on exactly without the results of your queries, but you're definitely doing something wrong here: you are trying to sort on a multi-valued field. One item is linked to multiple orders, each having its own date. So there is multiple dates per item.

When you ask to compare two items that each have three dates, what should Hibernate Search do? Compare only the latest dates? Compare only the earliest dates? You didn't say, so your query is bound to return inconsistently ordered results.

Thing is, there is no way to tell Hibernate Search which value to pick in multi-valued fields, so your easiest way out is to explicitly create a single-valued field to sort on.

For instance, you could add a getter on Item to return the latest order, and add the @IndexedEmbedded there:

@Entity
@Indexed
public class Item{
    @Id
    private long id;

    @Field(index = Index.YES, store = Store.YES, analyse = Analyse.YES, analyser = @Analyzer(definition = Constant.ANALYSER))
    private String description;

    @OneToMany(mappedBy = "item")
    @IndexedEmbedded
    private List<OrderPosition> orderPositions;

    @ManyToOne
    @IndexedEmbedded
    private Company company;           

    @javax.persistence.Transient
    public Order getLatestOrder() {
        Order latestOrder;
        // ... compute the latest order ...
        return latestOrder;
    }

    //getter&setter
}

Then sort on latestOrder.orderDate and you should be good.