Mapping one-to-many relationship using QueryDSL SQL

Question

Lets say I have this two bean entities:

public class Audit {

   private String code;

    private java.sql.Timestamp creationDate;

    private String creatorId;

    private java.sql.Timestamp deletionDate;

    private String description;

    private String id;

    private String name;

    private String notes;

    private Short status;

    private List<AuditParticipant> participants;
}

and :

 public class AuditParticipant {

    private String auditId;

    private String department;

    private String id;

    private String name;

    private String notes;

    private String role;

    private String surname;
}

... where Audit can have 1..n Participants, how can I use QueryDSL SQL to project the list of the participants into Audit bean (get all participants that belongs to audit)?

The beans were generated using QueryDSL code generation.

Thanks

Answer 1

Querydsl provides result aggregation functionality for such cases http://www.querydsl.com/static/querydsl/3.1.1/reference/html/ch03s02.html#d0e1634

In this case it would be something like

query.from(audit)
     .innerJoin(participant).on(...)
     .transform(groupBy(audit.id).as(audit, list(participant)));

See these examples for other groupBy options https://github.com/mysema/querydsl/blob/master/querydsl-collections/src/test/java/com/mysema/query/collections/GroupByTest.java