不相关表上的Spring Data，JPA和LEFT JOIN

Question

我有这个1-N案例

class BaseEntity {

  @Id
  Long id;

  String name;
}

class RelId {

  @Column(name = "BU_ID", nullable = false, insertable = true, updatable = true)
  private Long buId;

  @Column(name = "ID", nullable = false, insertable = true, updatable = true)
  private Long id;
}

class ExtA {

  @EmbeddedId
  private RelId id;

  @ManyToOne(optional = false, fetch = FetchType.LAZY)
  @JoinColumn(name = "ID", insertable = false, updatable = false)
  private BaseEntity baseEntity;
}

class ExtB {

  @EmbeddedId
  private RelId id;

  @ManyToOne(optional = false, fetch = FetchType.LAZY)
  @JoinColumn(name = "ID", insertable = false, updatable = false)
  private BaseEntity baseEntity;
}

class BaseEntityEx {

  BaseEntity baseEntity;
  ExtA extA;
  ExtB extB;
}

现在我想选择Base buId等于2的BaseEntityEx，并带有这样的查询

@Query(value = "SELECT NEW BaseEntityEx(b, ea, eb)
      + " FROM BaseEntity b "
      + " LEFT JOIN ExtA ea ON (ea.id.id=b.id AND ea.id.buId=:buId)"
      + " LEFT JOIN ExtB eb ON (eb.id.id=b.id AND eb.id.buId=:buId)"
      + " WHERE"
      + "   b.id=:id")
public BaseEntityEx getBaseEntityExByRelId(@Param("buId") long buId, @Param("id") long id);

但它不起作用。 我怎么能这样做？

  

P.S。我想在ExtA和ExtB上保持这种关系，因为当我   使用BaseEntity我不想懒惰地加载或不加载数百个   关系。

我获得的错误是：

antlr.SemanticException: Path expected for join!