Fetching a many-to-one DTO projection

[bacca87]

Issue description

Assuming we have 2 entities:

@MappedEntity
@Data
public class Book {
        @Id
        @GeneratedValue
        private int id;

        @NotNull
        private String title;

        @Relation(Relation.Kind.MANY_TO_ONE)
        private Author author;
}

@MappedEntity
@Data
public class Author {
    @GeneratedValue
    @Id
    private Long id;
    private final String name;
}

and the DTO:

@Introspected
public class AuthorDTO {
    private Long id;
    private final String name;
    private Set<int> books;
}

Is it possible to fetch the following query:

SELECT a.id, a.name, b.id as books
FROM author a 
INNER JOIN book b on b.author_id = a.id

results:

id	name	books
1	Stephen King	1
1	Stephen King	2
1	Stephen King	3

to the AuthorDTO creating only a single instance with a book list instead of creating 3 different DTOs?

[dstepanov]

At this moment DTOs don't support relations. You can try to annotate AuthorDTO with @MappedEntity that should use an ordinary entity mapper.

[bacca87]

I tried your workaround and it works!
I hope DTO relations will be supported soon...